Notes on Pyrophosphodiamic Acid. By J. H. Gladstone, Ph.D., F.R.S. 290 Researches on the Phosphates of Calcium, and upon the Solubility of Tricalcic On Chrysammic Ether. By John Stenhouse, LL.D., F.R.S., &c. Contributions from the Laboratory of the London Institution: 1. The Oxida- tion-products of the Propione produced from Carbonic Oxide and Sodium- ethyl. By J. Alfred Wanklyn.-2. On the Oxidation of Ethylamine. By J. A. Wanklyn and Ernest T. Chapman.-3. Action of Acids on Naphthylamine. By Ernest T. Chapman.-4. Production of Acetic and Propionic Acids from Amylic Alcohol. By Ernest T. Chap- man.-5. On some Decompositions of Nitrite of Amyl. By Ernest T. Preliminary Notice on Phthalic Aldehyde. By H. Kolbe and G. Wirchin. The Nitroprussides. By Edward Ash Hadow, King's College.. The Platinum Bases: the best mode of obtaining and identifying them; some new Compounds. By Edward Ash Hadow, King's College On a Cyanogen-derivative of Marsh-gas. By Henry Basset Note on the Hydrocarbons contained in crude Benzol. By C. Schorlemmer 356 Note on Ethyl-hexyl Ether. By C. Schorlemmer.. On the Reduction of the Oxides of Nitrogen by Metallic Copper in Organic Synthetical Researches on Ethers.-No. 1. Synthesis of Ethers from Acetic Ether. By E. Frankland, F.R.S., and B. F. Duppa, Esq. Action of Acids upon Metals and Alloys. By Dr. Crace Calvert, F.R.S., On some Products derived from Indigo-blue. By Edward Schunck, Ph.D., The Relation between the Products of gradual Oxidation and the Molecular Constitution of the bodies Oxidised. By Ernest Theophron Chap- On the Strength of Solutions of Phosphoric Acid of Various Densities. By Mr. John Watts, Senior Bell Scholar in the Laboratories of the Phar Note on Messrs. Calvert and Johnson's paper "On the Action of Acids upon JOURNAL OF THE CHEMICAL SOCIETY. I.-On Pyrophosphotriamic Acid. By J. H. GLADSTONE, Ph.D., F.R.S. Ir was my intention, in conjunction with my assistant and friend, Mr. J. D. Holmes, to follow up our previous papers on some of the amides of phosphoric acid* with a more complete investigation of the whole subject. But our paper on the action of ammonia on sulphochloride of phosphorus was scarcely printed, when Mr. Holmes was taken seriously ill, and his death, last midsummer, has deprived the world of a careful experimenter and a good man. I feel his loss the more because he had many thoughts and observations connected with these compounds of phosphorus, which he never committed to writing. On looking over our notebooks, I find a tolerably complete history of a remarkable acid amide, which, with a few additional experiments, will form the present communication. If dry ammonia gas be allowed to stream slowly into a flask containing oxychloride of phosphorus, kept cool by being immersed in water, the liquid is gradually converted into a white solid mass by the absorption of two equivalents of ammonia. If at that point the flask be immersed in water at 100° C., the mass will be found capable of absorbing two more equivalents of ammonia, and on the addition of water to the white substance thus produced, there results an insoluble amide, the subject of the present inquiry. In order to obtain it pure, the oxychloride of phosphorus employed must be free from pentachloride, but it is not necessary to attempt to free it from hydrochloric acid. During the latter portion of the * Journal Chem. Soc., 1864, p. 225, and 1865, p. 1. VOL. XIX. B process it is desirable to break up the solid mass from time to time, in order that all parts of it may be exposed to the gaseous ammonia; and if this be properly done, the contents of the flask will be found to have increased in weight nearly, if not quite, 44 per cent. The white amorphous powder produced by the action of water must be washed with cold water till the washings give no indication of a chloride, and then it is better to finish the washing with a little dilute alcohol. The compound thus obtained is tasteless, but when moistened it reddens blue litmus paper, and it effervesces with solutions of alkaline carbonates. When suspended in solutions of metallic salts, it usually decomposes them, entering into combination with the metal, and that in the presence of the liberated acid. These salts, so easily formed, are all insoluble or very sparingly soluble in water, like the acid itself, even the salts of the alkalis. Another remarkable circumstance connected with this acid is, that it is capable of combining with 1, 2, 3, or 4 atoms of the base, according to the peculiarities of the metal itself, or the way in which it is presented. This compound, though almost insoluble in water, is very slowly attacked by it, especially at a high temperature, with the production of pyrophosphodiamic acid. When boiled with dilute hydrochloric acid, it is speedily resolved into phosphoric acid and ammonia, pyrophosphodiamic acid being an intermediate product. When heated with strong sulphuric acid, it instantly dissolves, and this solution also contains pyrophosphodiamic acid. The following analyses were made of different preparations of the substance dried at 1C0° C. :— I. 03315 grm. boiled with hydrochloric acid, and the ammonia determined in the usual manner, gave 1.243 grm. of ammonio-chloride of platinum. II. 0.197 grm. gave 0.755 grm. of ammonio-chloride of platinum. III. 0.197 grm. decomposed in the same way gave 0.247 grm. of pyrophosphate of magnesium, IV. 0.2595 grm. gave 0.987 grm. of ammonio-chloride of platinum. V. 0.2445 grm. gave 0.309 grm.of pyrophosphate of magnesium. VI. 0.1845 grm. regained from its ammonium salt, gave 0.705 grm. of ammonio-chloride of platinum. VII. 0-225 grm. of substance regained from its combination with copper gave 0.2825 grm. of pyrophosphate of magnesium. VIII. 0.320 grm. burnt with oxide of copper gave 0.114 grm. of water. These numbers, when reckoned to 100 parts, give agreeing very closely with the numbers deduced from the formula This may be viewed as the third member of the series of amides of pyrophosphoric acid, of which the first two have already been described by me; and it should by analogy be termed pyrophosphotriamic acid. Pyrophosphotriamic acid .... P2N2H,→ or P23(NH2)H →4 4 The reaction by which this substance is produced by the treatment of oxychloride of phosphorus with ammonia and water in succession may be briefly expressed thus :— 2(PC1 ̧Ð + 4NH3) + 2H2O = P2N ̧H,→ + 6HCl + 5NH3, just as in the production of pyrophosphodiamic acid formerly described 2(PC1 ̧Ð + 2NH ̧) + 3H2Q = P21⁄2N2HË¿Ð ̧ + 6HCl + 2NH3, but in both cases there are intermediate products not recognized in the above equations. I reserve the fuller consideration of what takes place when ammonia is passed over oxychloride of phosphorus till a future occasion. SALTS. If the rational formula of this acid be that above given, it might be expected that only one equivalent of hydrogen would be replaceable by a metal, or, in other words, that pyrophosphotriamic acid would be monobasic, just as the diamic acid is bibasic, and the -amic acid is tribasic. The analysis of its salts shows indeed that such monobasic compounds are produced with the alkalimetals and many others, but it also shows that most metals are capable of displacing one or more equivalents of that hydrogen which we are apt to consider as more intimately associated with the nitrogen. SILVER-SALTS.-Monometallic.-If a solution of nitrate of silver be added to an aqueous solution of pyrophosphotriamic acid, it gives a white gelatinous precipitate. But it is not easy to prepare in this way a quantity sufficient for analysis, and a portion so produced gave a determination of silver, which led to the conclusion that the salt was impure. A better method is to suspend the acid in cold water, and add a solution of nitrate of silver, when a flocculent precipitate subsides, and becomes granular. It is white, amorphous, and insoluble in water; dilute nitric acid or ammonia will dissolve out a little silver, and leave the pure monometallic salt. This salt is decomposed at once by hydrochloric acid; and this affords a ready means for its analysis, as the pyrophosphotriamic acid itself is converted on boiling into phosphoric acid and ammonia, which can be determined in the usual way. The following determinations were obtained :- I. 0.259 grm. of silver-salt, washed with dilute ammonia, gave 0133 grm. of chloride of silver, and 0.208 of pyrophosphate of magnesium. II. 0·241 grm. similarly washed gave 0·122 grm. of chloride of silver, and 0.581 grm. of ammonio-chloride of platinum. III. 0.298 grm. of salt, washed with dilute nitric acid, gave 01515 grm. of chloride of silver, and 0-235 grm. of pyrophosphate of magnesium. IV. 0.285 grm., similarly washed, gave 0.145 grm. of chloride of silver, and 0.679 grm. of ammonio-chloride of platinum. |