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.
The relationship of these glycerides to glycerin is shown by the series of bodies formed from glycerin by replacement of hydrogen by "stearyl" (C18H350), the radical of stearic acid (C18H350.
Cicero and Livy bear testimony to the disappearance of a free plebs from the country districts and its replacement by gangs of slaves working on great estates.
This " replacement " of a " weak " acid by a " strong " one is a matter of common observation in the chemical laboratory.
The theory of past migrations from continent to continent, suggested by Cuvier to explain the replacement of the animal life which had become extinct through sudden geologic changes, was prophetic of one of the chief features of modern method - namely, the tracing of migrations.
Bevelment, as a term of crystallography, means the replacement of an edge of a crystal by two planes equally inclined to the adjacent planes.
When this process of replacement is complete, each terminated side of the funicular is the seat of two forces which neutralize one another, and there remain only two uncompensated forces, viz., those resident in the first and last sides of the funicular.
The material for lining, and the frequent replacement thereof, constitute the principal expense of the method.
Succession does not require their replacement by premolars.
In addition to this replacement of a single pair of functional teeth in each jaw, it has been discovered that marsupials possess rudimentary tooth-germs which never cut the gum.
There seems to have been a replacement of some of these teeth; and it has been suggested that this was of the marsupial type.
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."
Dumas gave especial attention to such substitutions, named metalepsy (µeraXntks, exchange); and framed the following empirical laws to explain the reactions: - (1) a body containing hydrogen when substituted by a halogen loses one atom of hydrogen for every atom of halogen introduced; (2) the same holds if oxygen be present, except that when the oxygen is present as water the latter first loses its hydrogen without replacement, and then substitution according to (1) ensues.
It has already been stated that benzene derivatives may be regarded as formed by the replacement of hydrogen atoms by other elements or radicals in exactly the same manner as in the aliphatic series.
81° 123° 112° 83° 42° - II° - 29° The replacement of one negative group by another is accompanied by a change in the boiling-point, which is independent of the compound in which the substitution is effected, and solely conditioned by the nature of the replaced and replacing groups.
By taking appropriate differences the following facts will be observed: (1) the replacement of potassium by rubidium occasions an increase in the equivalent volumes by about eight units, and of rubidium by caesium by about eleven units; (2) replacement in the same order is attended by a general increase in the three topic parameters, a greater increase being met with in the replacement of rubidium by caesium; (3) the parameters x and, p are about equally increased, while the increase in w is always the greatest.
Kryst., 1894), in his researches on the tetragonal potassium and ammonium dihydrogen phosphates and arsenates, found that the replacement of potassium by ammonium was attended by an increase of about six units in the molecular volume, and of phosphorus by arsenic by about 4.6 units.
Being equally, but only slightly, increased; replacement of phosphorus by arsenic was attended by a considerable increase, equally in x and >', while w suffered a smaller, but not inconsiderable, increase.
Hedenbergite, or calcium iron pyroxene, is a black mineral closely allied to diopside and, owing to the isomorphous replacement of iron by magnesium, there is no sharp line of division between them.
The replacement of detached mature proglottides at the distal end of the Cestode-body by others is not regeneration, for the replacing set has already developed, and in certain cases they can complete their development quite independently after being detached from the parent.
The replacement of one hydrogen atom by one alkyl or aryl group gives rise to primary amines; of two hydrogen atoms by two groups, to secondary amines; of three hydrogen atoms by three groups, to tertiary amines.
The chief peculiarities that distinguish Trematodes from their free-living allies, the Turbellaria, are the development of adhering organs for attachment to the tissues of the host; the replacement of the primitively ciliated epidermis by a thick cuticular layer and deeply sunk cells to ensure protection against the solvent action of the host; and (in one large order) a prolonged and peculiar life-history.
The hydrogen in ammonia is capable of replacement by metals, thus magnesium burns in the gas with the formation of magnesium nitride Mg3N2, and when the gas is passed over heated sodium or potassium, sodamide, NaNH 2, and potassamide, KNH 2, are formed.
Compounds are known which may be looked upon as derived from ammonia by the replacement of its hydrogen by the sulpho-group (HS0 3); thus potassium ammon-trisulphonate,N(SO 3 K) 3.2H20,is obtained as a crystalline precipitate on the addition of excess of potassium sulphite to a solution of potassium nitrite, KN02+3K2S03+2H20=N(S03K) 3 +4KHO.
QUINONES, in organic chemistry, a group of compounds in which two hydrogen atoms of a benzene nucleus are replaced by two oxygen atoms. This replacement may take place either in the ortho or para positions, giving rise to orthoquinones or to paraquinones; metaquinones do not appear to have been isolated.
Chemie, 1867, 3, p. 39), ascribes to the molecule a peroxide configuration which accounts for its oxidizing powers but not for the fact that each oxygen atom is capable of replacement by one atom of chlorine.
Immigration therefore, according to this theory, had amounted not to a reinforcement of our population, but to a replacement of native by foreign stock.
Replacement of -NH 2 by-OH:-The amine is diazotized and the aqueous solution of the diazonium salt is heated, nitrogen being eliminated and a phenol formed.
Replacement of -NH 2 by halogens and by the - CN and - CNO groups :- The diazonium salt is warmed with an acid solution of the corresponding cuprous salt (T.
Replacement of - NH 2 by - NO 2 :-A well - cooled concentrated solution of potassium mercuric nitrate is added to a cooled solution of benzene diazonium nitrate, when the crystalline salt 2C6H5N2 N03, Hg(N02)2 is precipitated.
Replacement of - NH 2 by hydrogen :-This exchange is brought about, in some cases, by boiling the diazonium salt with alcohol; but I.
After various repairs and strengthenings, including the replacement of the timber girder by an iron one in 1880, this bridge in 1896-1897 was taken down and a steel arch built _ _ __ _ I ?
The gradual replacement of Syriac by Arabic as the vernacular language of Mesopotamia by degrees transformed the Syriac from a living to a dead language.
Clarke (1889-1893) supposes them to be substitution derivatives of normal aluminium orthosilicate A14(S104)3, in which part of the aluminium is replaced by alkalis, magnesium, iron and the univalent groups (MgF), (A1F2),(AlO), (MgOH); an excess of silica is explained by the isomorphous replacement of H 4 SiO 4 by the acid H4S130s.
158.6 calories; this means that the replacement of a hydrogen atom by a methyl group is attended by a constant increase in the heat of combustion.
We have thus the replacement of a spermatheca, corresponding to those of the remaining families of Oligochaeta, and derived, as is believed, from the epidermis, by a structure performing the same function, but derived from the mesoblastic tissues, and with a cavity which is coelom.