Substances Sentence Examples

The word "flocculent" is used of many substances which have a fleecy or "flock"-like appearance, such as a precipitate of ferric hydrate.

The question again arises, what has become of the original substances?

Cellulose has an affinity for acid stains, pectic substances for basic stains.

In such cases the characters of the adult tissue clearly depend solely upon the characters of the cell-walls, and it is usual in plant-anatomy to speak of the wall with its enclosed cavity as the cell, and the contained protoplasm or other substances, if present, as cell-contents.

These layers arc secreted by the protoplasm by the direct apposition of substances on those already in existence; and they may go on increasing in thickness, both by apposition and by the intussusception of particles probably carried in through the protoplasmic fibres, which penetrate the cell-wall as long as the cell lives.

Cell-walls may become modified by the impregnation of various substances.

Woody or lignified cell-walls appear to contain substances called conifer-in and vanillin, in addition to various other compounds which are imperfectly known.

The sieve tubes contain a thin lining layer of protoplasm on their walls, but no nuclei, and the cell sap contains albuminous substances which are coagulable by heat.

He considered, for instance, that stems, leaves, roots and flowers differ as they do because the plastic substances entering into their structure are diverse.

This modification is important, because it transfers the formative influence from the plastic substances to the protoplasm, suggesting that, the diverse constituents are produced (whether spontaneously or as the result of stimulation) as secretions by the protoplasm.

The living elements die, and the walls of all the cells often become hardened, owing to the deposit in them of special substances.

If we examine the seat of active growth in a young root or twig, we find that the cells in which the organic substance, the protoplasm, of the plant is being formed and increased, are not supplied with carbon dioxide and mineral matter, but with such elaborated material as sugar and proteid substances, or others closely allied to them.

The general vegetable protoplasm has not the capacity of being nourished by inorganic substances which are denied to the living substance of the animal world.

It is sometimes forgotten, when discussing questions of animal nutrition, that all the food materials of all living organisms are prepared originally from inorganic substances in exactly the same way, in exactly the same place, and by the same machinery, which is the chlorophyll apparatus of the vegetable kingdom.

Like Anaximenes, he believed air to be the one source of all being, and all other substances to be derived from it by condensation and rarefaction.

It is also produced during the putrefaction of organic substances containing sulphur and is found among the products obtained in the destructive distillation of coal.

The bark and young cones afford a tanning material, inferior indeed to oakbark, and hardly equal to that of the larch, but of value in countries where substances more rich in tannin are not abundant.

His next and most important publication was his famous paper "On the Equilibrium of Heterogeneous Substances" (in two parts, 1876 and 1878), which, it has been said, founded a new department of chemical science that is becoming comparable in importance to that created by Lavoisier.

In God there is no distinction or difference, whereas in all substances or things there is duality, arising from the element of matter.

Between pure being and substances stand the ideas or forms, which subsist, though they are not substances.

The form or essence is one, the persons or substances three.

The gobies (Gobius) are small fishes readily recognized by their ventrals (the fins on the lower surface of the chest) being united into one fin, forming a suctorial disk, by which these fishes are enabled to attach themselves in every possible position to a rock or other firm substances.

Of these early writers, Hatchett is the most explicit, the various bituminous substances being by him classified and defined.

Bitumen is, in its various forms, one of the most widel y -distributed of substances, occurring in strata of every geological age, from the lowest Archean rocks to those now in process of deposition, and in greater or less quantity throughout both hemispheres, from Spitzbergen to New Zealand, and from California to Japan.

Stas carried out such experiments on the composition of silver chloride and of ammonium chloride, but he never found a variation of one part in 10,000 in the composition of the substances.

In another form the plumbago powder was worked into a button cemented together with syrup and other substances.

The curious signs on the coloured carboys in chemists' windows, which were commonly to be seen until the middle of the 19th century, were signs used by the alchemists to indicate various chemical substances.

The internal tissues, either consisting of obvious hyphae or of pseudoparenchyma, may also serve as a storehouse of plastic food substances.

In addition to the water-conducting tissue or hydrom there is a welldeveloped tissue (leptom) inferred to be a conducting channel for organic substances.

As this is not the incorporation of either into the living sobstance, but is only its manufacture into the complex substances which we find in the plant, it seems preferable to limit the term assimilation to the processes by which foods are actually taken into the protoplasm.

Several species of Dermestidae are commonly found in houses, feeding on cheeses, dried meat, skins and other such substances.

The mandibles are strong, adapted for biting the vegetable substances on which these beetles feed, and the palps of the second maxillae have three segments.

If we consider now the transformation of one system of chemical substances into another system under specified conditions, we shall find that in general the intrinsic energy of the second system is different from the intrinsic energy of the first.

It is also a necessary condition for the application of the preceding laws that no form of energy except heat and the intrinsic energy of the substances should be ultimately involved.

The calorimeter used for solutions is usually cylindrical, and made of glass or a metal which is not, attacked by the reacting substances.

Combustion calorimeters are employed for observing the heat generated by the brisk interaction of substances, one of which at least is gaseous.

In the older type the combustion chamber (of metal or glass) is sunk in the calorimeter proper, tubes being provided for the entrance and exit of the gaseous substances involved in the action.

When substances in solution are dealt with, Thomsen indicates their state by affixing Aq to their symbols.

With knowledge then of the heats of formation of the substances involved in any chemical action, we can at once calculate the thermal effect of the action, by placing for each compound in the energy-equation its heat of formation with the sign reversed, i.e.

A much better approximation to the heat of combustion of such substances is obtained by deducting the oxygen together with the amount of carbon necessary to form C02, and then ascertaining the amount of heat produced by the residual carbon and hydrogen.

When substances readily combine with water to form hydrates, the heat of solution in water is usually positive; when, on the other hand, they do not readily form hydrates, or when they are already hydrated, the heat of solution is usually negative.

They live on small animals or soft vegetable substances, which they root up from the bottom.

Berthelot, and many other chemists, from whose researches it results that glycerin is a trihydric alcohol indicated by the formula C 3 H 5 (OH) 3j the natural fats and oils, and the glycerides generally, being substances of the nature of compound esters formed from glycerin by the replacement of the hydrogen of the OH groups by the radicals of certain acids, called for that reason "fatty acids."

It is noticeable that with few exceptions the fatty and oily matters occurring in nature are substances analogous to tristearin, i.e.

In its medicinal use glycerin is an excellent solvent for such substances as iodine, alkaloids, alkalis, &c., and is therefore used for applying them to diseased surfaces, especially as it aids in their absorption.

Most of these were simple records of patient and laborious analytical operations, and it is perhaps surprising that among all the substances he analysed he only detected two new elements - beryllium (1798) in beryl and chromium (1797) in a red lead ore from Siberia.

Soaking the seed in strong-smelling substances, such as paraffin and turpentine, has been found efficacious, and in some districts paraffin sprayed over the seedlings has been practised with decided success.

The bark, split off in May or June, forms one of the most valuable tanning substances in Canada.

His first contributions to mathematical physics were two papers published in 1873 in the Transactions of the Connecticut Academy on "Graphical Methods in the Thermodynamics of Fluids," and "Method of Geometrical Representation of the Thermodynamic Properties of Substances by means of Surfaces."

The earlier supporters of the organic theory held that it was a product of the natural distillation of coal or carbonaceous matter; but though in a few instances volcanic intrusions appear to have converted coal or allied substances into oil, it seems that terrestrial vegetation does not generally give rise to petroleum.

By blending the coco-nut oil with other less saponifiable substances such as tallow, lard, cotton-seed oil, &c., and effecting the mixing and saponification at a slightly higher temperature, soaps are obtained which resemble milled toilet soaps.

Soaps are also prepared in which large proportions of fine sharp sand, or of powdered pumice, are incorporated, and these substances, by their abrading action, powerfully assist the detergent influence of the soap on hands much begrimed by manufacturing operations.'

Medicated soaps, first investigated scientifically by Unna of Hamburg in 1886, contain certain substances which exercise a specific influence on the skin.

The most important points in soap analysis are (1) determination of the fatty matter, (2) of the total alkali, (3) of the substances insoluble in water, (4) of the water.

The residue on the filter paper gives (3) the substances insoluble in water.

Regarding all substances as being composed of one primitive matter - the prima materia, and as owing their specific differences to the presence of different qualities imposed upon it, the alchemist hoped, by taking away these qualities, to obtain the prima materia itself, and then to get from it the particular substance he desired by the addition of the appropriate qualities.

They first invented and named the alembic for the purposes of distillation, analyzed the substances of the three kingdoms of nature, tried the distinction and affinities of alkalis and acids, and converted the poisonous minerals into soft and salutary remedies.

Increasing attention was paid to the investigation of the properties of substances and of their effects on the human body, and chemistry profited by the fact that it passed into the hands of men who possessed the highest scientific culture of the time, Still, belief in the possibility of transmutation long remained orthodox, even among the most distinguished men of science.

For example, the physicist determines the density, elasticity, hardness, electrical and thermal conductivity, thermal expansion, &c.; the chemist, on the other hand, investigates changes in composition, such as may be effected by an electric current, by heat, or when two or more substances are mixed.

The fundamental chemical classification of matter, on the other hand, recognizes two groups of substances, namely, elements, which are substances not admitting of analysis into other substances, and compounds, which do admit of analysis into simpler substances and also of synthesis from simpler substances.

From the Alexandrians the science passed to the Arabs, who made discoveries and improved various methods of separating substances, and afterwards, from the 11th century, became seated in Europe, where the alchemical doctrines were assiduously studied until the 15th and 16th centuries.

From the mazy and incoherent alchemical and iatrochemical doctrines, the former based on false conceptions of matter, the latter on erroneous views of life processes and physiology, a new science arose - the study of the composition of substances.

Georg Ernst Stahl, following in some measure the views held by Johann Joachim Becher, as, for instance, that all combustibles contain a " sulphur " (which notion is itself of older date than Becher's terra pinguis), regarded all substances as capable of resolution into two components,.

Berzelius, who, fired with enthusiasm by the original theory of Dalton and the law of multiple proportions, determined the equivalents of combining ratios of many elements in an enormous number of compounds.2 He prosecuted his labours in this field for thirty years; as proof of his industry it may be mentioned that as early as 1818 he had determined the combining ratios of about two thousand simple and compound substances.

This attitude was due to his adherence to the " dualistic theory" of the structure of substances, which he deduced from electrochemical researches.

From the behaviour of substances on electrolysis he assumed that all substances had two components, one bearing a negative charge, the other a positive charge.

A second inconsistency was presented when he was compelled by the researches of Dumas to admit Avogadro's hypothesis; but here he would only accept it for the elementary gases, and denied it for other substances.

This link was the full extension of Avogadro's theory to all substances, Cannizzaro showing that chemical reactions in themselves would not suffice.

This spirit gave way to the physicians, who regarded " chemistry as the art of preparing medicines," a denotation which in turn succumbed to the arguments of Boyle, who regarded it as the " science of the composition of substances," a definition which adequately fits the science to-day.

He emphasized that the practical training should include (1) the qualitative and quantitative analysis of mixtures, (2) the preparation of substances according to established methods, (3) original research - a course which has been generally adopted.

An acid (q.v.) is a compound of hydrogen, which element can be replaced by metals, the hydrogen being liberated, giving substances named salts.

When two substances which by their action upon each other develop much heat enter into reaction, the reaction is usually complete without the employment of an excess of either; for example, when a mixture of hydrogen and oxygen, in the proportions to form water 2E12+0, =20H2, is exploded, it is entirely converted into water.

This is also the case if two substances are brought together in solution, by the action of which upon each other a third body is formed which is insoluble in the solvent employed, and which also does not tend to react upon any of the substances present; for instance, when a solution of a chloride is added to a solution of a silver salt, insoluble silver chloride is precipitated, and almost the whole of the silver is removed from solution, even if the amount of the chloride employed be not in excess of that theoretically required.

But if there be no tendency to form an insoluble compound, or one which is not liable to react upon any of the other substances present, this is no longer the case.

In this, as in most other cases in which substances act upon one another under such circumstances that the resulting compounds are free to react, the extent to which the different kinds of action which may occur take place is dependent upon the mass of the substances present in the mixture.

Chemical change which merely involves simple decomposition is thus seen to be influenced by the masses of the reacting substances and the presence of the products of decomposition; in other words the system of reacting substances and resultants form a mixture in which chemical action has apparently ceased, or the system is in equilibrium.

Every year is attended by fresh " discoveries " in this prolific source of elementary substances, but the paucity of materials and the predilections of the investigators militate in some measure against a just valuation being accorded to such researches.

Organic Chemistry While inorganic chemistry was primarily developed through the study of minerals - a connexion still shown by the French appellation chimie minerale - organic chemistry owes its origin to the investigation of substances occurring in the vegetable and animal organisms. The quest of the alchemists for the philosopher's stone, and the almost general adherence of the iatrochemists to the study of the medicinal characters and preparation of metallic compounds, stultified in some measure the investigation of vegetable and animal products.

It is true that by the distillation of many herbs, resins and similar substances, several organic compounds had been prepared, and in a few cases employed as medicines; but the prevailing classification of substances by physical and; superficial properties led to the correlation of organic and inorganic compounds, without any attention being paid to their chemical composition.

The clarification and spirit of research so clearly emphasized by Robert Boyle in the middle of the 17th century is reflected in the classification of substances expounded by Nicolas Lemery, in 1675, in his Cours de chymie.

Notwithstanding the inconsistency of his allocation of substances to the different groups (for instance, acetic acid was placed in the vegetable class, while the acetates and the products of their dry distillation, acetone, &c., were placed in the mineral class), this classification came into favour.

It thus happened that in the earlier treatises on phlogistic chemistry organic substances were grouped with all combustibles.

Theoretical speculations were revived by Lavoisier, who, having explained the nature of combustion and determined methods for analysing compounds, concluded that vegetable substances ordinarily contained carbon, hydrogen and oxygen, while animal substances generally contained, in addition to these elements, nitrogen, and sometimes phosphorus and sulphur.

He also postulated, with Regnault, the existence of " molecular or mechanical types " containing substances which, although having the same number of equivalents, are essentially different in characters.

This description, although not absolutely comprehensive, serves as a convenient starting-point for a preliminary classification, since a great number of substances, including the most important, are directly referable to hydrocarbons, being formed by replacing one or more hydrogen atoms by other atoms or groups.

The introduction of hydroxyl groups into the benzene nucleus gives rise to compounds generically named phenols, which, although resembling the aliphatic alcohols in their origin, differ from these substances in their increased chemical activity and acid nature.

These substances absorb water and become pimelic acids.

It is well known that singly, doubly and trebly linked carbon atoms affect the physical properties of substances, such as the refractive index, specific volume, and the heat of combustion; and by determining these constants for many substances, fairly definite values can be assigned to these groupings.

During recent years an immense number of ringed or cyclic compounds have been discovered, which exhibit individual characters more closely resembling benzene, naphthalene, &c. than purely aliphatic substances, inasmuch as in general they contain double linkages, yet withstand oxidation, and behave as nuclei, forming derivatives in much the same way as benzene.

Fiveand six-membered rings are the most stable and important, the last-named group resulting from the polymerization of many substances; threeand four-membered rings are formed with difficulty, and are easily ruptured; rings containing seven or more members are generally unstable, and are relatively little known.

Systems which are generally unsaturated compounds, often of considerable stability, and behave as nuclei; these compounds constitute a well-individualized class exhibiting closer affinities to benzenoid substances than to the open-chain series.

Thelfirst four substances are readily formed from, and converted into, the corresponding dihydroxy open-chain compound; these substances are truly aliphatic in character.

Six-membered ring systems can be referred back, in a manner similar to the above, to pyrone, penthiophene and pyridine, the substances containing a ring of five carbon atoms, and an oxygen, sulphur and nitrogen atom respectively.

Experimental conditions were thoroughly worked out; the necessity of working with hot or cold solutions was clearly emphasized; and the employment of small quantities of substances instead of the large amounts recommended by Klaproth was shown by him to give more consistent results.

For substances of a difficultly combustible nature he adopted the method in common use to-day, viz.

Moisture is evolved from substances containing water of crystallization or decomposed hydrates.

Certain substances, such as the precious metals, are quite insoluble in the bead, but float about in it.

Certain substances are insoluble in all these reagents, and other methods, such as the fusion with sodium carbonate and potassium nitrate, and subsequent treatment with an acid, must be employed.

It is unnecessary here to dwell on the precautions which can only be conveniently acquired by experience; a sound appreciation of analytical methods is only possible after the reactions and characters of individual substances have been studied, and we therefore refer the reader to the articles on the particular elements and compounds for more information on this subject.

Lead chromate is sometimes used, and many other substances, such as platinum, manganese dioxide, &c., have been suggested.

Substances which burn with difficulty may be mixed with mercuric oxide in addition to copper oxide.

The first class includes those substances which require no preliminary treatment, and comprises the amides and ammonium compounds, pyridines, quinolines, alkaloids, albumens and related bodies; the second class requires preliminary treatment and comprises, with few exceptions, the nitro-, nitroso-, azo-, diazoand amidoazo-compounds, hydrazines, derivatives of nitric and nitrous acids, and probably cyanogen compounds.

It may be surmised that the quantitative measures of most physical properties will be found to be connected with the chemical nature of substances.

In any attempts to gain an insight into the relations between the physical properties and chemical composition of substances, the fact must never be ignored that a comparison can only be made when the particular property under consideration is determined under strictly comparable conditions, in other words, when the molecular states of the substances experimented upon are identical.

When this is done, such densities are measures of the molecular weights of the substances in question.

Experiment, however, showed that while the quotient on the left hand of this equation was fairly constant for a great number of substances, yet its value was not gR but 7 R; this means that the critical density is, as a general rule, 3.7 times the theoretical density.

Theoretical considerations as to how far Kopp was justified in choosing the boiling-points under atmospheric pressure as being comparable states for different substances now claim our attention.

If we express the pressure, volume and temperature as fractions of the critical constants, then, calling these fractions the " reduced " pressure, volume and temperature, and denoting them by 7r, 0 and 0 respectively, the characteristic equation becomes (7+3/0 2)(30-i) =80; which has the same form for all substances.

Guldberg pointed out that for the most diverse substances the absolute boiling-point is about two-thirds of the critical temperature.

He introduced the idea of comparing the refractivity of equimolecular quantities of different substances by multiplying the function (n-1)/d by the molecular weight (M) of the substance, and investigated the relations of chemical grouping to refractivity.

In the case of substances possessing anomalous dispersion, the direct measurement of the refractive index for Hertzian waves of very long wave-length may be employed.

By subtracting the value for CH 2, which may be derived from two substances belonging to the same homologous series, from the molecular refraction of methane, CH 4, the value of hydrogen is obtained; subtracting this from CH 2, the value of carbon is determined.

Since molecular refractions are independent of temperature and of the state of aggregation, it follows that molecular dispersions must be also independent of these conditions; and hence quantitative measurements should give an indication as to the chemical composition of substances.

A clear distinction must be drawn between colour and the property of dyeing; all coloured substances are not dyes, and it is shown in the article Dyeing that the property of entering into chemical or physical combination with fibres involves properties other than those essential to colour.

At the same time, however, all dyestuffs are coloured substances.

A survey of coloured substances led 0.

With basic substances, the chromophoric combination with a colourless acid is generally attended by a deepening in colour; auxochromic combination, on the other hand, with a lessening.

Mention may be made of the phenomenon of halochromism, the name given to the power of colourless or faintly-coloured substances of combining with acids to form highly-coloured substances without the necessary production of a chromophoric group. The researches of Adolf von Baeyer and Villiger, Kehrmann, Kauffmann and others, show that this property is possessed by very many and varied substances.

It follows on this theory that all coloured substances contain either of the groupings or the former being a para-quinonoid, the latter an ortho-quinonoid.

While very many coloured substances must obviously contain this grouping, yet in many cases it is necessary to assume a simple intermolecular change, while in others a more complex rearrangement of bonds is necessary.

The quinonoid structure of many coloured compounds has been proved experimentally, as, for example, by Hewitt for the benzene-azo-phenols, and Hantzsch for triaminotriphenyl methane and acridine derivatives; but, at the same time, many substances cannot be so explained.

In the free state these substances are colourless, and were assumed to have the formula shown in i.

An alternative view, due to Green, is that the oxygen atom of the xanthone ring is tetravalent, a supposition which permits the formulation of these substances as ortho-quinonoids.

Researches in synthetical organic chemistry have shown that this property of fluorescenceis common to an immense number of substances, and theories have been proposed whose purpose is to connect the property with constitution.

Although the theories of Meyer and Hewitt do not explain (in their present form) the behaviour of anthranilic acid, yet Hewitt has shown that his theory goes far to explain the fluorescence of substances in which a double symmetrical tautomerism is possible.

Isomorphism may be defined as the existence of two or more different substances in the same crystal form and structure, polymorphism as the existence of the same substance in two or more crystal modifications, and morphotropy (after P. von Groth) as the change in crystal form due to alterations in the molecule of closely (chemically) related substances.

As a general rule the modification stable at higher temperatures possesses a lower density; but this is by no means always the case, since the converse is true for antimonious and arsenious oxides, silver iodide and some other substances.

It is remarkable that a great many polymorphous substances assume more symmetrical forms at higher temperatures, and a possible explanation of the increase in density of such compounds as silver iodide, &c., may be sought for in the theory that the formation of a more symmetrical configuration would involve a drawing together of the molecules, and consequently an increase in density.

The mere retention of the same crystal form by homologous substances is not a sufficient reason for denying a morphotropic effect to the substituent group; for, in the case of certain substances crystallizing in the cubic system, although the crystal form remains unaltered, yet the structures vary.

When both the crystal form and structure are retained, the substances are said to be isomorphous.

If a substance deposits itself on the faces of a crystal of another substance of similar crystal form, the substances are probably isomorphous.

More useful is the property of isomorphous substances of forming mixed crystals, which are strictly isomorphous with their constituents, for all variations in composition.

He also investigated the diamagnetic and paramagnetic properties of substances; and was keenly interested in the phenomena of electrochemical decomposition, accumulating much evidence in favour of Faraday's law and proposing a modified statement of it which was intended to cover certain apparent exceptions.

Bituminous products of every grade, from clear translucent oils resembling petroleum and refined naphtha, to lignite-like substances, occur in all parts of the island.

It does not burn, but supports the combustion of heated substances almost as well as oxygen.

Paal has also obtained pyrrol derivatives by condensing acetophenone-acetoacetic-ester with substances of the type NH2R.

Typical plants are holophytic, that is, they obtain their food substances from purely mineral sources.

Therefore all life in the sea (as on land) depends on the power which the holophytic organisms possess of synthesizing mineral substances into organized tissues.

All these substances exist as only a fraction of one part or, at most, a few parts, per million of water.

In the case of all these substances the quantities involved are so very small, and the difficulties of estimation are therefore so great, that the information we possess is by no means satisfactory.

It follows, too, that when there is a number of substances, all essential for the elaboration of living material, and when one of these is present in minimal proportion, that one substance rules the production, just as the effective strength of a chain depends on the weakest link.

The concentration of these substances is least in the warm equatorial seas and greatest near the poles.

The bottom water is relatively rich in these substances as well as in decaying organic matter, and would become progressively richer but for the slow drift towards the equator and the welling-up of bottom water to the surface in these latitudes.

The vegetable kingdom is the original source of albuminous substances, the albumins being found in greatest quantity in the seed.

They are usually insoluble in water, alcohol and ether; and their presence as solutes in vegetable and animal fluids is not yet perfectly understood, but it is probably to be connected with the presence of salts or other substances.

These substances are combinations of one or more albumins with a radical of an essentially different nature, termed by Kossel a " prosthetic group."

Albuminoids is the anatomical name given to albuminous substances forming the connective tissues.

The albumoids include, according to Cohnheim, substances which possess certain properties in common, but differ from the preceding groups.

He found that the amounts of the substances liberated in each cell were proportional to the chemical equivalent weights of those substances.

If the current be so strong that new hydrogen and hydroxyl ions cannot be formed in time, other substances are liberated; in a solution of sulphuric acid a strong current will evolve sulphur dioxide, the more readily as the concentration of the solution is increased.

If two solutions containing the salts AB and CD be mixed, double decomposition is found to occur, the salts AD and CB being formed till a certain part of the first pair of substances is transformed into an equivalent amount of the second pair.

In simple substances like potassium chloride it seems evident that one kind of dissociation only is possible.

It is possible that in complicated organic substances we might have two kinds of dissociation, electrical and non-electrical, occurring simultaneously, while the possibility of the association of molecules accompanied by the electrical dissociation of some of them into new parts should not be overlooked.

The tests for a salt, potassium nitrate, for example, are the tests not for KNO 3, but for its ions K and NO 3, and in cases of double decomposition it is always these ions that are exchanged for those of other substances.

Thus neither a chlorate, which contains the ion C103, nor monochloracetic acid, shows the reactions of chlorine, though it is, of course, present in both substances; again, the sulphates do not answer to the usual tests which indicate the presence of sulphur as sulphide.

For some substances it has been shown to be independent of the particular reaction used.

In the case of substances like ammonia and acetic acid, where the dissociation is very small, I - a is nearly equal to unity, and only varies slowly with dilution.

The value of k, however, does not keep constant so satisfactorily in the case of highly dissociated substances, and empirical formulae have been constructed to represent the effect of dilution on them.

When the solutions of two substances are mixed, similar considerations to those given above enable us to calculate the resultant changes in dissociation.

In dilute solution such substances as hydrochloric acid and potash are almost completely dissociated, so that, instead of representing the reaction as HC1+KOH = KC1 d-H20, we must write The ions K and Cl suffer no change, but the hydrogen of the acid and the hydroxyl (OH) of the potash unite to form water, which is only very slightly dissociated.

In ordinary cells the difference is secured by using two dissimilar metals, but an electromotive force exists if two plates of the same metal are placed in solutions of different substances, or of the same substance at different concentrations.

The proteids should be as far as possible removed during the preparation of the rubber, as these substances are chiefly responsible for the objectionable smell and colour of " native " rubbers, and their presence leads to subsequent change in the commercial material.

At present the caoutchouc present in crude rubber is usually estimated indirectly, and it is possible that what generally passes as caoutchouc may be in some instances a mixture of similar chemical substances, which if separated would be found to differ in those physical properties on which the technical value of rubber depends.

There are many substances produced by plants which can be synthetically prepared by chemical means, but, as with quinine, the process involved is too costly to enable the synthetic product to compete with the natural product.

This is drawn off, cooled and filtered, and forms a white paint of good body, consisting of about 65% lead sulphate, 26% lead oxide, 6% zinc oxide and 3% other substances.

Iron and its alloys, including the various kinds of steel, though exhibiting magnetic phenomena in a pre-eminent degree, are not the only substances capable of magnetization.

Practically the metals iron, nickel and cobalt, and some of their alloys and compounds constitute a class by themselves and are called ferromagnetic substances.

But it was discovered by Faraday in 1845 that all substances, including even gases, are either attracted or repelled by a sufficiently powerful magnetic pole.

Those substances which are attracted, or rather which tend, like iron, to move from weaker to stronger parts of the magnetic field, are termed paramagnetic; those which are repelled, or tend to move from stronger to weaker parts of the field, are termed diamagnetic. Between the ferromagnetics and the paramagnetics there is an enormous gap. The maximum magnetic susceptibility of iron is half a million times greater than that of liquid oxygen, one of the strongest paramagnetic substances known.

The direction of the magnetization is that of the magnetic axis of the element;'in isotropic substances it coincides with the direction of the magnetic force at the point.

Hence if the induction per square centimetre at any point is denoted by B, then in empty space B is numerically equal to H; moreover in isotropic media both have the same direction, and for these reasons it is often said that in empty space (and practically in air and other nonmagnetic substances) B and H are identical.

The permeability of most material substances differs very slightly from unity, being a little greater than I in paramagnetic and a little less in diamagnetic substances.

The circulation of magnetic induction or flux through magnetic and non-magnetic substances, such as iron and air, is in many respects analogous to that of an electric current through good and bad conductors.

The principal points of difference are that (I) the magnetic permeability, unlike the electric conductivity, which is independent of the strength of the current, is not in general constant; (2) there is no perfect insulator for magnetic induction, which will pass more or less freely through all known substances.

Equations (33) and (34) show that when, as is generally the case with ferromagnetic substances, the value of is considerable, the resultant magnetic force is only a small fraction of the external force, while the numerical value of the induction is approximately three times that of the external force, and nearly independent of the permeability.

The coefficient K/(i +171-K) is positive for ferromagnetic and paramagnetic substances, which will therefore tend to move from weaker to stronger parts of the field; for all known diamagnetic substances it is negative, and these will tend to move from stronger to weaker parts.

For small bodies other than spheres the coefficient will be different, but its sign will always be negative for diamagnetic substances and positive for others; hence the forces acting on any small body will be in the same directions as in the case of a sphere' Directing Couple acting on an Elongated Body.

It can be shown 3 that in a uniform field an elongated piece of any non-crystalline material is in stable equilibrium only when its length is parallel to the lines of force; for diamagnetic substances, however, the directing couple is exceedingly small, and it would hardly be possible to obtain a uniform field of sufficient strength to show the effect experimentally.

The presence of ordinary impurities usually tends to diminish the permeability, though, as will appear later, the addition of small quantities of certain other substances is sometimes advantageous.

A very pure form of iron, which from the method of its manufacture is called " steel," is now extensively used for the construction of dynamo magnets; this metal sometimes contains not more than 0.3% of foreign substances, including carbon, and is magnetically superior to the best commercial wrought iron.

Heusler 2 in 1903 that certain alloys of the non-magnetic metal manganese with other non-magnetic substances were strongly magnetizable, their susceptibility being in some cases equal to that of cast iron.

In the second series, to which greater importance is attached, measurements were made of the force exerted in a divergent field upon small balls of copper, silver and other substances, first when the balls were in air and afterwards when they were immersed in liquid oxygen.

For all diamagnetic substances, except antimony and the value of K was found to be independent of the temperature.

To account for diamagnetism, Weber supposed that there exist within the molecules of diamagnetic substances certain channels around which an electric current can circulate without any resistance.

He also carried out some new experiments on the effects of heat, and of screening by magnetic substances, and investigated the influence of shape upon the magnetization of iron.

The hydrazones are crystalline substances which are of value in the characterization of the aldehydes.

Different substances were distinguished by the name of "alumen"; but they were all characterized by a certain degree of astringency, and were all employed in dyeing and medicine, the light-coloured alumen being useful in brilliant dyes, the dark-coloured only in dyeing black or very dark colours.

As alum and green vitriol were applied to a variety of substances in common, and as both are distinguished by a sweetish and astringent taste, writers, even after the discovery of alum, do not seem to have discriminated the two salts accurately from each other.

The alum schists employed in the manufacture of alum are mixtures of iron pyrites, aluminium silicate and various bituminous substances, and are found in upper Bavaria, Bohemia, Belgium and Scotland.

But the Platonically conceived proof of the being of God contained in the Monologion shows that Anselm's doctrine of the universals as substances in things (universalia in re) was closely connected in his mind with the thought of the universalia ante rem, the exemplars of perfect goodness and truth and justice, by participation in which all earthly things are judged to possess these qualities.

The most interesting part of the work is the distinction which Gilbert draws between the manner of existence of genera and species and of substances proper.

Genera and species certainly exist, but they do not exist in their own right as substances.

As against Realism he maintains consistently Res de re non praedicatur; genera and species, therefore, which are predicated of the individual subject, cannot be treated as things or substances.

Several different products may be obtained by the reduction of the aromatic nitro compounds, the substances formed in any particular case depending on the conditions of experiment.

The stones at the bottom are slightly reddish, owing to vegetable substances.

Recent investigations point to the conclusion that the immediate cause of the arrest of vitality, in the first place, and of its destruction, in the second, is the coagulation of certain substances in the protoplasm, and that the latter contains various coagulable matters, which solidify at different temperatures.

The nitrates are also very insoluble substances, all the so-called solvents merely converting them into jelly.

Strong or weak solutions of these substances also decompose it, producing some alkali nitrate and nitrite, the cellulose molecule being only partially restored, some quantity undergoing oxidation.

It has a strong and characteristic odour, and a hot sweetish taste, is soluble in ten parts of water, and in all proportions in alcohol, and dissolves bromine, iodine, and, in small quantities, sulphur and phosphorus, also the volatile oils, most fatty and resinous substances, guncotton, caoutchouc and certain of the vegetable alkaloids.

Leber experimented with several chemical compounds to find what reaction they had on these cells; by using fine glass tubes sealed at the outer end and containing a chemical substance, and by introducing the open end into the blood vessels he found that the leucocytes were attracted - positive chemiotaxis - by the various compounds of mercury, copper, turpentin, and other substances.

The vessels are only temporary channels by which is brought forward the food supply that is needed by the advancing army if it is suc-, cessfully to carry on its function; they probably also drain off the deleterious fluid substances formed by the cellular disintegration that has taken place in the part.

It is believed also that they secrete bactericidal substances and ferments which bring about the liquefaction of the fibrin and the damaged tissues - histolysis - and thus assist the process of absorption.

These substances may be formed in the cells and given out as a secretion, or they may be formed by an intercellular transformation.

In the mucinoid conditions, usually termed "mucoid " and " colloid " degenerations, we have closely allied substances which, like the normal mucins of the body, belong to the glucoproteids, and have in common similar physical characters.

The connective tissue is supplied normally with a certain amount of these mucinoid substances, no doubt acting as a lubricant.

These represent the albuminoid series, and are probably elaborated by the cells from albuminous substances through the influence of specific ferments.

In extraneous pigmentation we have coloured substances either in a solid or fluid state, gaining entrance into the organism and accumulating in certain tissues.

The reaction with iodine is seen best by direct light; the reactions with the other substances are visible only by transmitted light.

It is now known to have nothing in common with vegetable cellulose, but is regarded as one of the many albuminoid substances existing in the body under pathological conditions.

Massart and Bordet, Leber, Metchnikoff and others have studied the phenomenon in leucocytes, with the result that while there is evidence of their being positively chemiotactic to the toxins of many pathogenic microbes, it is also apparent that they are negatively influenced by such substances as lactic acid.

The addition of some of the liquid squeezed out from a blood-clot, of the squeezed blood-clot itself, or of a little blood-serum, is sufficient to throw down a fibrinous coagulum (Buchanan), evidently by these substances supplying the fibrin-ferment.

Certain peculiar substances, probably degenerative products, some of them reducing copper, are occasionally met with.

According to Rogowicz and Heidenhain, certain substances increase the quantity of lymph given off from a part by acting upon the cells of the capillary wall; they hold, in fact, that these substances are true lymphagogues.

Heidenhain recognizes two classes, first, such substances as peptone, leech extract and crayfish extract; and, secondly, crystalloids such as sugar, salt, &c. Starling sees no reason to believe that members of either class act otherwise than by increasing the pressure in the capillaries or by injuring the endothelial wall.

It crystallizes (in long needles) more easily when gently agitated during the cooling, or when mixed with such substances as kieselguhr.

To prevent the freezing of nitroglycerin in dynamite it has been proposed to add various substances, such as chlordinitroglycerin, nitrated diglycerin or tetranitrodiglycerol, and also mono-and di-nitroglycerin.

Now as our own bodies thus manipulate substances poisonous and antidotal, if in every hour of health we are averting selfintoxication, so likewise are we concerned with the various intruding organisms, whose processes of digestion are as dangerous as our own; if these destructive agents, which no doubt are incessantly gaining admission to our bodies, do not meet within us each its appropriate compensatory defensive agent, dissolution will begin.

So various are the conditions of selfregulation in various animals, both in respect of their peculiar and several modes of assimilating different foods, and of protecting themselves against particular dangers from without, that, as we might have expected, the bloods taken from different species, or even perhaps from different individuals, are found to be so divergent that the healthy serum of one species may be, and often is, poisonous to another; not so much in respect of adventitious substances, as because the phases of physiological change in different species do not harmonize; each by its peculiar needs has been modified until, in their several conditions of life, they vary so much about the mean as to have become almost if not quite alien one to another.

Among the revisions may be adduced some addition to our knowledge of dyspepsia, attained by analytic investigations into the contents of the stomach at various stages of digestion, and by examining the passage of opaque substances through the primae vine by the Rntgen rays.

In the sphere of physiology and in the interpretation of associated arterial diseases much obscurity still remains; as, for instance, concerning the nature of the toxic substances which produce those bilateral changes in the kidneys which we call Bright's disease, and bring about the "uraemia" which is characteristic of it.

The ancient Egyptians used various substances as incense.

Thus the Orphic hymns are careful to specify, in connexion with the several deities celebrated, a great variety of substances appropriate to the service of each; in the case of many of these the selection seems to have been determined not at all by their fragrance but by some occult considerations which it is now difficult to divine.

These substances condense to form tetra-aminotriphenylmethane, which, on heating with acids, loses ammonia and yields diaminodihydrophenylacridine, from which benzoflavin is obtained by oxidation.

Aided by grants from the Prussian government, these workers systematically investigated the effect of introducing a large number of different chemical substances (oxides) into vitreous fluxes.

A certain proportion of soda ash (carbonate of soda) is also used in some works in sheet-glass mixtures, while " decolorizers " (substances intended to remove or reduce the colour of the glass) are also sometimes added, those most generally used being manganese dioxide and arsenic. Another essential ingredient of all glass mixtures containing sulphate of soda is some form of carbon, which is added either as coke, charcoal or anthracite coal; the carbon so introduced aids the reducing substances contained in the atmosphere of the furnace in bringing about the reduction of the sulphate of soda to a condition in which it combines more readily with the silicic acid of the sand.

For the commoner grades of dark-coloured bottles the glass mixture is cheapened by substituting common salt for part of the sulphate of soda, and by the addition of felspar, granite, granulite, furnace slag and other substances fusible at a high temperature.

The substances employed are the same as those used for the manufacture of sheet-glass, viz.

It is easily broken down by many substances (aluminium chloride, zinc chloride, &c.) into ethyl chloride and carbon dioxide.

Round disks made of these substances were placed in a closely fitting cylindrical cavity drilled in a block of steel, the cavity having a circular aperture of two or four centimetres below.

Metallic Substances Produced by the Union of Metals with Small Proportions of Non-Metallic Elements.

Chemically it is one of the most interesting substances known, since it is the parent of the enormous number of compounds styled the " aromatic " or " benzenoid " compounds.

Fischer's a-acrose therefore led to the synthesis of the dextro and laevo forms Gf mannose, glucose and fructose; and these substances have been connected synthetically with many other sugars by means of his cyanhydrin process, leading to higher sugars, and Wohl and.

The reader is referred to Glucose and Fructose for an account of these substances.

The fact of this increased leucocytic activity during the early stages, or the whole course of infection by Cestodes, is indirect proof that these parasites do normally discharge toxic substances into their hosts.

The subsoil not unfrequently contains materials which are deleterious to the growth of crops, and roots descending into it may absorb and convey these poisonous substances to other parts of the plant or be themselves damaged by contact with them.

The inorganic materials within it supply some of the chief substances utilized by plants for their development and growth, and from plants animals obtain much of their sustenance.

The oxygen of the air may also bring about chemical changes which result in the production of soluble substances removable by rain, the insoluble parts being left in a loosened state.

A perfect soil would be such a blend of sand, clay, chalk and humus as would contain sufficient clay and humus to prevent drought, enough sand to render it pervious to fresh air and prevent waterlogging, chalk enough to correct the tendency to acidity of the humus present, and would have within it various substances which would serve as food-materials to the crops.

The space between the parts of such substances is too large to admit of capillary action; hence the water conveyed to the surface of the soil is prevented from passing upwards any further except by slow evaporation through the mulching layer.

Whereas the soil used to be looked upon solely as a dead, inert material containing certain chemical substances which serve as food constituents.

The compounds of ammonia thus formed from the complex substances by many varied kinds of micro-organisms are ultimately oxidized into nitrates.

It is present in variable amounts in limestones of all kinds, although its white ness may there be masked by the presence of iron oxide and other coloured substances.

Their growth makes no new addition of mineral food-constituents to the land, but they bring useful substances from the subsoil nearer to the surface, and after the decay of the buried vegetation these become available to succeeding crops of wheat or other plants.

The results of many analyses show that the capacity of soils for moisture increases with the amount of organic substances present; decomposition appears to be most active when the moisture is about 4%, but can continue when it is as low as 2%, while it appears to be retarded by any excess over 4%.

Heated with many metals it converts them into oxides, and with combustible substances, such as charcoal, sulphur, &c., a most intense conflagration occurs.

His contributions to inorganic chemistry were numerous, including investigations on the compounds of antimony, aluminium, silicon, &c., on the separation of nickel and cobalt, and on the analysis of mineral waters, but they are outweighed in importance by his work on organic substances.

Further work on cyanogen and connected substances yielded a great number of interesting derivatives, and he described an improved method for the manufacture of potassium cyanide, an agent which has since proved of enormous value in metallurgy and the arts.

On this theory he prepared artificial manures containing the essential mineral substances together with a small quantity of ammoniacal salts, because he held that the air does not supply ammonia fast enough in certain cases, and carried out systematic experiments on ten acres of poor sandy land which he obtained from thr town of Giessen in 1845.

They feed upon nearly all vegetable substances, but drink little.

The pure substances are best obtained by fusion of the corresponding toluene sulphonic acids with potash.

In many of these the application of heat is necessary to bring the substances used into the liquid state for the purpose of electrolysis, aqueous solutions being unsuitable.

Several modifications were proposed, in one of which, intended for the heating of non-conducting substances, the electrodes were passed horizontally through perforations in the upper part of the crucible walls, and the charge in the lower part of the crucible was heated by radiation.

In these processes the electric current is used solely to generate heat, either to induce chemical reactions between admixed substances, or to produce a physical (allotropic) modification of a given substance.

They are of importance, since the higher homologues are identical in many cases with the ptomaines produced by the putrefactive action of some bacteria on albumen and other related substances.

These substances are treated in the article Aniline.

Since many substances decompose either at, or below, their boiling-points under ordinary atmospheric pressure, it is necessary to lower the boiling-point by reducing the pressure if it be desired to distil them.

Practically any vessel may serve as a receiver - test tube, flask, beaker, &c. If noxious vapours come over, it is necessary to have an air-tight connexion between the condenser and receiver, and to pro vide the latter with an outlet tube leading to an absorption column or other contrivance in which the vapours are taken up. If the substances operated upon decompose when heated in air, as, for example, the zinc alkyls which inflame, the air within the apparatus is replaced by some inert gas, e.g.

This method is adopted for substances which decompose at their boiling-points under ordinary pressure, and, generally, when it is desirable to work at a lower temperature.

This method is particularly successful in the case of substances which cannot be distilled at their ordinary boiling-points (it will be seen in the following section that distilling with steam implies a lowering of boiling-point), and which can be readily separated from water.

With substances prone to discolorization, as, for example, certain amino compounds, the operation may be conducted in an atmosphere of carbon dioxide, or the water may be saturated with sulphuretted hydrogen.

Dry distillation is extremely wasteful even when definite substances or mixtures, such as calcium acetate which yields acetone, are dealt with, valueless by-products being obtained and the condensate usually requiring much purification.

In its simplest form the apparatus consists of a straight tube, made of glass, porcelain or iron according to the temperature required and the nature of the reacting substances, heated in an ordinary combustion furnace, the mixture entering at one end and the vapours being condensed at the other.

Probably all of them secrete an active poison by the aid of their glands, but the effects of these substances are not readily perceptible.

Kopp devoted himself especially to physico-chemical inquiries, and in the history of chemical theory his name is associated with several of the most important correlations of the physical properties of substances with their chemical constitution.

The censer, to use the more general term, is a vessel which contains burning charcoal on which the aromatic substances to be burned are sprinkled.

The periodical histolysis may be partly due to the absence of specific excretory organs and to the accumulation of pigmented excretory substances in the wall of the alimentary canal.

On the degeneration of the polypide, its nutritive material is apparently absorbed for the benefit of the zooid, while the pig mented substances assume a spheroidal form, which either remains as an inert "brown body" in the body-cavity or is discharged to the exterior by the alimentary canal of the new polypide.

The first volume, Vegetable Staticks (1727), contains an account of numerous experiments in plant-physiology - the loss of water in plants by evaporation, the rate of growth of shoots and leaves, variations in root-force at different times of the day, &c. Considering it very probable that plants draw "through their leaves some part of their nourishment from the air," he undertook experiments to show in "how great a proportion air is wrought into the composition of animal, vegetable and mineral substances"; though this "analysis of the air" did not lead him to any very clear ideas about the composition of the atmosphere, in the course of his inquiries he collected gases over water in vessels separate from those in which they were generated, and thus used what was to all intents and purposes a "pneumatic trough."

The two worlds of nature and spirit are perfectly distinct, but they are intimately related by analogous substances, laws and forces.

The same inventor has patented the application of electrolysed chlorides to the purification of starch by the oxidation of less stable organic bodies, to the bleaching of oils, and to the purification of coal gas, spirit and other substances.

Of the general characters of acids we may here notice that they dissolve alkaline substances, certain metals, &c., neutralize alkalies and redden many blue and violet vegetable colouring matters.

Vinegar (or impure acetic acid), which is produced when wine is allowed to stand, was known to both the Greeks and Romans, who considered it to be typical of acid substances; this is philologically illustrated by the words OEbs, acidus, sour, and duos, acetus, vinegar.

At about the same time Boyle investigated several acids; he established their general reddening of litmus, their solvent power of metals and basic substances, and the production of neutral bodies, or salts, with alkalies.

Somewhat similar views were held by Berzelius, when developing his dualistic conception of the composition of substances.

The substances which we at present term anhydrous acids (acid oxides) only become, for the most part, capable of forming salts with metallic oxides after the addition of water, or they are compounds which decompose these oxides at somewhat high temperatures."

Oxy-acids are carboxylic acids which also contain a hydroxyl group; similarly we may have aldehyde-acids, ketone-acids, &c. Since the more important acids are treated under their own headings, or under substances closely allied to them, we shall here confine ourselves to general relations.

In the preceding instances the carboxyl group has been synthesized or introduced into a molecule; we have now to consider syntheses from substances already containing carboxyl groups.

The animal cell can absorb its carbohydrate and proteid food only in the form of carbohydrate and proteid; it is dependent, in fact, on the pre-existence of these organic substances, themselves the products of living matter, and in this respect the animal is essentially a parasite on existing animal and plant life.

It may conveniently be extended to similar mixtures of sulphur and selenium or tellurium, of bismuth and sulphur, of copper and cuprous oxide, and of iron and carbon, in fact to all cases in which substances can be made to mix in varying proportions without very marked indication of chemical action.

If we melt copper and add to it about 30% of zinc, or 20 of tin, we obtain uniform liquids which when solidified are the well-known substances brass and bell-metal.

These substances are for all practical purposes new metals.

In this case the white tin-rich portions are themselves a complex that can be resolved into two substances by a higher magnification.

Let us suppose that a molten mixture of two substances A and B, which at a sufficiently high temperature form a uniform liquid, and which do not combine to form definite compounds, is slowly cooled until it becomes wholly solid.

In the case of two substances which neither form compounds nor dissolve each other in the solid state, the complete freezing-point curve takes the form shown infig.5.

The bodies SbNa 3, BiNa3, SnNa 4, compounds of iron and molybdenum and many other substances, have also been isolated in this way.

The difference between softness and hardness in ordinary steel is due to the permanence of a solid solution of carbon in iron if the steel has been chilled or very rapidly cooled, while if the steel is slowly cooled this solid solution breaks up into a minute complex of two substances which is called pearlite.

The formulae of the group of substances last mentioned are in harmony with the ordinary views of chemists as to valency, but the formulae NaHg 2, NaCd 2, NaT1 2, AuAl 2 are more surprising.

There are very few substances, however, for which the optical refractive index has the same value as K for steady or slowly varying electric force, on account of the great variation of the value of K with frequency.

It simply asserts that the efficiency function F'(t), which is known as Carnot's function, is the same for all substances at the same temperature.

Skey showed that in substances which contain small quantities of gold the precious metal may be removed by the solvent action of iodine or bromine in water.

Gold readily alloys with silver and copper to form substances in use from remote times for money, jewelry and plate.

Other undesirable impurities are the platinum metals, special treatment being necessary when these substances are present.

The metal can be reduced by magnesium, zinc, cadmium, iron, tin, copper and substances like hypophosphorous acid from acid solutions or from alkaline ones by formaldehyde.

The separate determination of the volume and mass of such substances as gunpowder, cotton-wool, soluble substances, &c., supplies the only means of determining their densities.

In 1826 Dumas devised a method suitable for substances of high boiling-point; this consisted in its essential point in vaporizing the substance in a flask made of suitable material, sealing it when full of vapour, and weighing.

It is to be noted, however, that this method is applicable to substances of any boiling-point (see below).

These substances, and also carbon, sulphur, selenium and tellurium, render the metal very brittle.

But the two substances were generally confounded as "fixed alkali" (carbonate of ammonia being "volatile alkali"), till Duhamel du Monceau in 1736 established the fact that common salt and the ashes of seaplants contain the same base as is found in natural deposits of soda salts ("mineral alkali"), and that this body is different from the "vegetable alkali" obtained by incinerating land plants or wood (pot-ashes).

The rich colour of the grass is due to the fertilizing quality of the decaying fungi, which are peculiarly rich in nitrogenous substances.

That nothing analogous to bitumen exists in coals is proved by the fact that the ordinary solvents for bituminous substances, such as bisulphide of carbon and benzol, have no effect upon them, as would be the case if they contained bitumen soluble in these re-agents.

Percy, the mineral matter being also changed by the removal of silica and alkalis and the substitution of substances analogous in composition to fire-clay.

There are three substances which can be relied on more or less to remove this compound, and the gas to be purified may be passed either through acid copper salts, through bleaching powder or through chromic acid.

In the following table are given the values of the diameters of the molecules of six substances with which it is easy to experiment in the gaseous state, these values being calculated in different ways from formulae supplied by the kinetic theory.

When a liquid undergoing evaporation is contained in a closed vessel, a molecule which has left the liquid will, after a certain 1 Other processes also help in the conduction of heat, especially in substances which are conductors of electricity.

It is not at present necessary to suppose that the molecules are those of substances in the gaseous state.

On this theory, all substances which could be burnt were composed of phlogiston and some other substance, and the operation of burning was simply equivalent to the liberation of the phlogiston.

Belmont, what is the use of the prayers offered up over the substances; and how account for the differences of effects which by the testimony of the faithful are respectively caused by water duly blessed and by water falsely blessed?

Alcohol is produced by fermentation from vegetable substances containing starch or sugar, from fermentable sugars produced by the hydrolysis of cellulosic bodies, and synthetically from calcium carbide and from the ethylene contained in coal and coke-oven gases.

These vegetable substances may be divided into foodstuffs and nonfoodstuffs.

Investigations started in 1920 by the British Government, in connexion with the production of alcohol for power purposes, have shown, however, that there are large areas of suitable land in the British Empire where the cost of production would be comparatively low, and where it might be possible to grow vegetable substances in excess of food requirements, and in sufficient quantities to produce alcohol for local consumption to replace expensive petrol.

Mineral, vegetable and animal substances, by means of tools and apparatus of stone, wood and bone - tools for cutting, or edged tools; tools for abrading and smoothing the surfaces of substances, like planes, rasps and sandpaper; tools for striking, that is, pounding for the sake of pounding, or for crushing and fracturing violently; perforating tools; devices for grasping and holding firmly.

These varied in the different culture provinces according to the natural supply, and the presence or absence of good tool material counted for as much as the presence or absence of good substances on which to work.

No standards of weighing or measuring were known, but the parts of the body were the units, and money consisted in rare and durable vegetable and animal substances, which scarcely reached the dignity of a mechanism of exchange.

With this animal diet everywhere vegetable substances were mixed, even in the boreal regions.

In the manufacture of these the substances were reduced to the form of slender filaments, shreds, rods, splints, yarn, twine and sennit or braid.

Everywhere there were names for a large number of species; industries and fine arts were developed through animal substances.

Chemical methods of sterilization have also been suggested, depending on the use of iodine, chlorine, bromine, ozone, potassium permanganate, copper sulphate or chloride and ()their substances.

They feed on various vegetable substances, as shoots of trees and bushes, American Tapir (Tapirus).