862. "The oxidation of propyl-glycol yields, according to the conditions of the experiment, lactic or glycolic acid. (C, H1)" O, +20 C, H,O,+ H2O 3 (CH) } O, +4O= C, H, O, + CO,+ HẠO 863. "Glyceric acid may be converted into lactic acid, and tartronic acid into glycolic acid. The transformation of glyceric and tartronic acids, and their composition, support the view, therefore, that they are connected in the same manner as oxalic and glycolic acids. 864. "According to our knowledge of several salts of glyceric acid, this substance appears to be monatomic; but if we consider its derivation from glycerine, the view of M. Wurtz, who considers glyceric acid to be triatomic, is very probably correct. (C, H, O)"} O,, glyceric acid. H, This point, however, requires further investigation."Debus. -- 865. Formation of glyceramine. When monochlorhydrine acts on ammonia, the hydrochlorate of a base called glyceramine is formed, Cl C, H, ON. HOẠN. 866. Transformation of glycerine into propyl-glycol.— When an aqueous solution of monochlorhydrine is acted upon at the common temperature with an amalgam of sodium, it is converted into propyl-glycol. 867. Decomposition of glycerine by potash.-When glycerine is gently heated with hydrate of potash or soda, it is decomposed, hydrogen is liberated, and acetate and formiate of potash are formed. 868. There can be no doubt that if we were to employ, in place of terbromide of allyl, the iodides, bromides, or chlorides of other triatomic radicals, corresponding triatomic alcohols would be formed. EXERCISE. 157. Write out the formula of the following bodies. and state how you would prepare them:-Monoleine, dibu tyrine, monovalerine, tribenzocy ine, dipalmytine, tristearine, benzochlorhydrine. APPENDIX F. APPENDIX TO GLYCERINE Group. 869. Lourenço has quite recently obtained polyglycerines which stand in the same relation to glycerine as the polyethylenic bodies do to glycol. For further information respecting these polyglycerines, the student is referred to the Répertoire de Chimie Pure," vol. iii., page 147. NEGATIVE Group. 870. This group embraces-(1) The mineral triatomic acids. (2) The organic triatomic acids, and the salts of these acids. TRIATOMIC ACIDS. 871. The substitution of a triatomic acid radical for three atoms of hydrogen in three molecules of water, produces a triatomic acid. 872. Tribasic acids are not volatile without decomposition. They can form three classes of salts, according as they exchange one, two, or three atoms of hydrogen for a metal. Examples : (PO)" } 03 K, S 873. These acids can give with each alcohol three ether salts, one of which is neutral, and the other two are acid. 874. Considered in the state of vapour, under the same volume, the neutral ethers (tertiary ethers) of the tribasic acids contain three times the amount of the alcohol radical which the neutral ethers of the monobasic acids contain. 875. The ammoniacal salts of the tribasic acids are not volatile without decomposition. Their amides are still little known; however, we have already obtained some acid amides and diamides which correspond to the tribasic acids. 876. Considered in the state of vapour, under the same volume, the chlorides of the tribasic acids contain three times the amount of chloride which the chlorides of monobasic acids contain. (1.) MINERAL ACIDS. 877. The following are the principal tribasic inorganic acids: 878. Only a small number of triatomic organic acids is known.t FIRST CLASS. 879. Glyceric acid appears to be monobasic, but its salts have as yet been but little investigated. From its derivation from the triatomic body, glycerine, it must be triatomic, and it will bear the same relation to one or perhaps two series of acids which lactic acid bears to the oxalic. Its formula, represented as a triatomic acid, is (C, H, O)" O.. H, The composition of the pyrophosphates is M, P, O.; they may be viewed as formed by the union of an atom of orthophosphate with an atom of metaphosphate. + Dr. Maxwell Simpson has quite recently obtained a tribasic acid by acting upon tercyanide of allyl with potasb. SECOND CLASS. 880. There must be an acid standing to glyceric acid in the same relation as oxalic acid stands to glycolic acid, and the acid must be triatomic, and probably will be tribasic. Debus thinks that tartronic acid occupies this relation. This acid as yet has only been prepared from the spontaneous decomposition of nitro-tartaric acid. It forms a neutral and acid salt with ammonia; it has therefore been considered to be bibasic, and homologous with malic acid; but if the view of Debus be correct, it must be a triatomic acid. Its formula would, in accord(C, H O2)" } ance with this view, be FOURTH CLASS. 881. We shall merely give the names and formula of the following acids: (C, H, O1)" (C. H, Os)" H1 } 882. The anhydrides of these acids have not been obtained. EXERCISE. 158. Write out the formula of the following salts and ethers: Primary phosphate of potassium, secondary citrate of sodium, tertiary phosphate of calcium, primary phosphoric ethyl-ether (monethyl phosphoric acid), tertiary phosphoric ethyl-ether (neutral phosphate of ethyl), secondary phosphoric ethyl ether (biethyl phosphoric acid), biethyl citric acid. 883. The only body we shall notice under this type is silicic acid. 884. Dr. Odling has recently directed attention to the basicity of silicic acid. He regards this acid as a tetrabasic acid, and he bases this opinion upon the following facts:-"We are acquainted with various binary compounds of hydrogen, and with certain quadroxy acids and salts indirectly procurable from them, thus: Chlorhydric acid H CIH CIO. - Perchloric acid Sulphydric acid . H.SH,SO, Sulphuric acid Phosphamine - H, PH,PO - Phosphoric acid And it seems to be a general rule, that binary hydrides, with one, two, three, or more atoms of hydrogen, yield quadroxy acids and salts, with an equal number of atoms of hydrogen, or equivalents of basic metals, respectively." 885. If one equivalent of water (H2O) is removed from the phosphoric acid, we obtain what is termed metaphosphoric acid, and as this acid has, like perchloric acid, only one atom of basic hydrogen, it is, like that acid, monobasic, it unites only with one atom of base. Now the tribasic salts we shall term orthophosphates,* and the monobasic ones metaphosphates. 886. Between the meta and ortho-phosphates there is an intermediate class, which may be viewed as composed of an atom of each of the two salts named, viz., meta and ortho-salts. M, PO, M, PO, M, P, O, 887. When phosphoric anhydride (P, O,) is fused with a salt, it depends upon the facility with which the anhydride of that salt can be driven off, whether we obtain an ortho, meta, or intermediate phosphate. Thus, Dr. Odling finds that when sulphate of magnesium is heated with phosphoric anhydride, orthophosphate of magnesium (Mg, PO) is produced, because sulphuric anhydride is somewhat readily expelled from magnesia; but when phosphoric anhydride is fused with sulphate of potassium, only metaphosphate of potassium (KPO,) is produced, because sulphuric anhydride is powerfully retained by potassa. The phosphoric acid obtained from the magnesium salt gave a yellow precipitate with ammonio-nitrate of silver, and did not coagulate albumen. The phosphoric For an explanation of this term, see par. 707. |