Chemical method, notation, classification, & nomenclature / by Auguste Laurent ; translated by William Odling.

  • Laurent, Auguste, 1807-1853.
Date:
1855
Catalogue details

Licence: Public Domain Mark

Credit: Chemical method, notation, classification, & nomenclature / by Auguste Laurent ; translated by William Odling. Source: Wellcome Collection.

    399/414
    may remark, that it lias also been designated by the name of pyrocateckine, whence we should conclude, that its acid properties are not well marked. We are acquainted with its lead salt only, and we know that with certain neutral bodies, and with feeble acids, lead frequently gives rise to salts containing an excess of oxide. But I leave this last objection on one side, since there exists a derivative of oxyphenic acid, namely, the oxypicric C6H3X3 + 02 (if, indeed, it does not contain O9 instead of 0s), which gives rise to bibasic salts. That the acid in question constitutes the real phenic deuteridc, appears to me to be very doubtful, inasmuch as St. Evre has obtained from benzoic acid (the intimate relations of which with the phenic series are well known to us) two acids, namely, the chlorophenylic and nitrochlorophenylic, which are respectively represented by C6H*C1 + O2 and C6H4 X Cl+O2, and are mono- basic. And since the rule, that every acid, no matter what its degree of basity, conserves that degree of basity when undergoing eh loro-and nitro- substitutions, is hitherto without exception; we thence conclude, that the chloro- and nitro-chlorophcnylic acids are derived from a monobasic acid C6H6 + 02, which is indeed the real phenic deuteridc. With regard to pyrocatcchine, it has obviously a relation of propinquity with the phenic series ; but we arc unable at the present time to determine its functions with certainty. We have now to consider the saturating capacities of the acids. The weight of the molecule of an acid being known, how are we to ascertain its saturating capacity ? Nothing is more simple in appearance; we determine the quantity of hydrogen which can be replaced by its equivalent of metal: if 1 atom of hydrogen is replaced by 1 atom of metal, the acid is monobasic; if 2, 3, &c. atoms of hydrogen are replaced by 2, 3, &c. atoms of metal, the acid is bi-, tri-, &c. basic. Never- theless there are cases in which somewhat serious difficulties present themselves. We do not require to know, whether tartaric acid, for example, is mono- or bi- basic, that is to say, whether or not its formula ought to be doubled, for we have already examined this question in all its details; but representing the acid by C4H60G, we require to know, how many of its hydrogen atoms, it is capable of exchanging for an equal number of metallic atoms. It is generally admitted, that two atoms of hydrogen may be exchanged for 2 atoms of any metal whatever. I would ask, whether we are perfectly sure, that the acid is 2 u 2