The astringent principle is a peculiar kind of tannic acid, called by chemists quercitannic, which, yielding more stable compounds with gelatine than other forms, gives oak bark its high value to the tanner.
By using urea, guanidine, thiourea and related compounds instead of amidines, one obtains the uracils.
For the preparation of yttrium compounds the best raw material is gadolinite, which, according to Kiinig, consists of 22.61% of silica, 34.64.
Technology compounds over time.
Pure terbium compounds were obtained by G.
His first original paper (1799) was on the compounds of arsenic and antimony with oxygen and sulphur, and of his other separate investigations one of the most important was that on the compound ethers, begun in 1807.
Molybdenum combines with the halogen elements in varying proportions, forming with chlorine a di-, tri-, tetraand penta-chloride, and similar compounds with bromine and iodine.
A study of the whole vegetable kingdom, however, negatives the theory that the compounds absorbed are in the strict sense to be called food.
Those Fungi which are saprophytic can only live when supplied with organic compounds of some complexity, which they derive from decomposing animal or vegetable matter.
In addition, certain inorganic salts, particularly certain compounds of potassium, are apparently necessary, but they seem to take no part in the chemical changes which take place.
The mono-amino derivatives or eurhodines are obtained when the arylmonamines are condensed with orthoamino zo compounds; by condensing quinone dichlorimide or para-nitrosodimethyl aniline with monamines containing a free para position, or by oxidizing ortho-hydroxydiaminodiphenylamines (R.
He was the first to discover uranium, zirconium and titanium, and to characterize them as distinct elements, though he did not obtain any of them in the pure metallic state; and he elucidated the composition of numerous substances till then imperfectly known, including compounds of the then newly recognized elements: tellurium, strontium, cerium and chromium.
Now, as the materials which plants absorb are carbon dioxide from the air, and various inorganic compounds from the soil, together with water, it is clear that if this view is correct, vegetable protoplasm must be fed in a very different way from animal, and on very different materials.
When the young sporophyte first begins its independent lifewhen, that is, it exists in the form of the embryo in the seedits living substance has no power of utilizing the simple inorganic compounds spoken of.
As the action of the chlorophyll apparatus is directly dependent upon light, and the immediate result of its activity is the building up of complex compounds, it has become usual to speak of the processes it sets up under the name of photosynthesis.
Habitats rich in mineral salts, especially calcium carbonate, poor in acidic humous compounds, and characterized by ash woods, beech woods, and calcareous pasture.
Civilization, like technology, also compounds over time, as do its benefits.
The law of multiple proportions asserts that if two elements form more than' one compound, then the weights of the one element Law of which are found combined with unit weight of the other multiple in the different compounds, must be in the ratio of two propor or more whole numbers.
To this attitude he offered uncompromising opposition, and by the synthetical production of numerous hydrocarbons, natural fats, sugars and other bodies he proved that organic compounds can be formed by ordinary methods of chemical manipulation and obey the same laws as inorganic substances, thus exhibiting the "creative character in virtue of which chemistry actually realizes the abstract conceptions of its theories and classifications - a prerogative so far possessed neither by the natural nor by the historical sciences."
In two cases, however, it has been found in the absence of appreciable quantities of uranium and thorium compounds, namely in beryl, and in sylvine (potassium chloride).
Of these compounds, the primary amides of the type Rï¿½COï¿½NH 2 are the most important.
They form compounds with hydrochloric acid when this gas is passed into their ethereal solution; these compounds, however, are very unstable, being readily decomposed by water.
Many organic compounds of boron are known; thus, from the action of the trichloride on ethyl alcohol or on methyl alcohol, ethyl borate B(OC2H5)3 and methyl borate B(OCH 3) 3 are obtained.
345), that only compounds containing two carbon atoms yielded fulminates, points to (Hcno) 2; on the other hand, Wohler (loc. cit.
The fungus seems to do better when supplied with compounds of ammonia.
Up to very recently the original absorption and subsequent treatment of the carbon dioxide and the compounds of nitrogen has been called by the same term.
Similar observations have been made in the case of various compounds of nitrogen, though these have not been so complex as the proteids.
Long ago the view that this gas might be the source of the combined nitrogen found in different forms within the plant, was critically examined, particularly by Boussingault, and later by Lawes and Gilbert and by Pugh, and it was ascertained to be erroneous, the plants only taking nitrogen into their substance when it is presented to their roots in the form of nitrates of various metals, or compounds of ammonia.
This is the absorption of elaborated compounds from their environment, by whose decomposition the potential energy expended in their construction can be liberated.
This source is not, however, anything new, for the elaborated compounds so absorbed have been primarily constructed by other plants through the mechanism which has just been described.
In such cells as are capable of absorbing it, by virtue oi their chlorophyll apparatus, the greater part of it is converted int< the potential form, and by the transport from cell to cell of th compounds constructed every part of the plant is put into possessiol of the energy it needs.
Obviously no more than this is possible until physiologists are able to state much more precisely than at present what is the influence of common salt on the plants of salt-marshes, of the action of calcium carbonate on plants of calcareous soils, and of the action of humous compounds on plants of fens and peat moors.
~rphytes, grow in soils which contain an abundance of free imous compounds, and include plants which grow on fens and le .oors.
Mineral salts, especially calcium carbonate, often rich in acidic humous compounds, and characterized by oak and birch woods, siliceous pasture, and heaths with much acidic humus in the sandy soil.
Woody or lignified cell-walls appear to contain substances called conifer-in and vanillin, in addition to various other compounds which are imperfectly known.
Similar sodium and ammonium compounds are known.
Fortunately, the compounds at first examined by the chemists engaged in verifying these laws were comparatively simple, so that the whole numbers referred to above were small.
If chemical compounds can be proved by experiment to obey these laws, then the atomic theory acquires a high degree of probability; if they are contradicted by experiment then the atomic theory must be abandoned, or very much modified.
The assumption was arbitrary, based on no valid evidence.
The symbols of compounds become very concise, as the number of atoms of one kind in a molecule can be expressed by a sub-index.
A large number of cobalt compounds are known, of which the empirical composition represents them as salts of cobalt to which one or more molecules of ammonia have been added.
Fermentation now includes all changes in organic compounds brought about by ferments elaborated in the living animal or vegetable cell.
PYRIMIDINES, METADIAZINES or Miazines, in organic chemistry, a series of heterocyclic compounds containing a ring complex, composed of four carbon atoms and two nitrogen atoms, the nitrogen atoms being in the meta-position.
In 1831, from a study of the specific heats of compounds, he formulated "Neumann's law," which expressed in modern language runs: "The molecular heat of a compound is equal to the sum of the atomic heats of its constituents."
ACID-AMIDES, chemical compounds which may be considered as derived from ammonia by replacement of its hydrogen with acidyl residues, the substances produced being known as, primary, secondary or tertiary amides, according to the number of hydrogen atoms replaced.
If not, there must exist in the green plant, side by side with it, another mechanism which is concerned with the manufacture of the complex compounds in which nitrogen is present.
It is certain that their protoplasm cannot be nourished by inorganic compounds of nitrogen, any more than that of animals.
The organic compounds of the latter are absorbed by the protruding fungal filaments, which take the place of root-hairs, the tree ceasing to develop the latter.
Witt), and by the decomposition of ortho-anilido-(-toluidido- &c.)-azo compounds with dilute acids.