furnishing similarly coloured solutions, or even with the mixed solution of the chlorides of iron, cobalt, and copper, afterwards proposed by Eggertz. The solution of ammonium nitrographitoate furnishes light to dark brown flocculent precipitates with solutions of metallic salts. "The barium salt obtained in this way, gave, on analysis, the values The lead salt contained 60-78 per cent. of lead oxide." On comparing the researches of Schützenberger and Donath, it will be seen that Schützenberger and Bourgeois set up the formula CHO, for their "graphite hydrate," whereas, according to Donath's report (assuming that only oxygen is present in addition to the carbon and hydrogen ascertained by the ultimate analysis), the formula works out to C58H33029, or perhaps C6H34030. This gives the atomic ratio, carbon hydrogen = 1.833, or 1.757 and 1.764, and therefore a somewhat defective concordance, which seems to indicate that we have to do with a mixture of several substances, and not with a uniform body. A comparison of the analyses of the nitro-products gives which furnishes, by calculation, the formulæ C22H17(NO2)O11 and C47H32(NO2)2025. By doubling the first of these we have C44H34(NO2)2O22, i.e. 3CO less, but H2 more, than the formula deduced from Donath's analysis, thus supporting our previous hypothesis. a result equally speaking in favour of a mixture. Finally, if we compare the analyses of carbazeic acid and its barium salt (according to Donath)— If, however, we remember that, in comparison with the barium salt, the acid must contain twice as many hydrogen atoms as the former has barium atoms, and the composition of the acid on the basis of 3.81 atoms of hydrogen, we obtain Carbazeic Acid. Barium Salt. 5.64 atoms hence calculate 2.69+2 x 0.56 Difference. Carbon Consequently the acid must contain considerably more carbon than the barium salt, which is equally impossible; it therefore follows that the so-called carbazeic acid is a mixture of compounds, only a portion of which can be precipitated by barium salts. The analysis of the barium compound gives by calculation the empirical formula C1H3(NO2)O17Bаg, which is so complex as to lead to the belief that this compound also is a mixture of different salts. Osmond and Werth selected a steel of the following composition for solution by the Weyl method: The resulting residue was washed with water, alcohol, and ether, dried in vacuo, and weighed on a tared filter. The resulting data, as well as the method of treating the steel, are given in the subjoined table : 1 Mémorial de l'Artillerie de la Marine, 1887, p. 240. These analyses, as well as the appearance of the samples, show the residue to consist of a mixture of grey magnetic spangles of metallic appearance (apparently undecomposed iron carbide) with a blackish amorphous, gelatinous substance, the latter preponderating in hardened steel, but receding in importance in annealed steel. On calculating the iron content as carbide, and referring the results to equal quantities of carbon, we obtain― Even though the carbohydrates in the two last columns could be approximately expressed by the formulæ— or in a similar manner, it is still impossible to regard the first two as mixtures of the foregoing, and it is therefore evident that a thorough investigation is still necessary for the elucidation of the matter. It is, however, interesting to draw into comparison the results obtained by Sir Frederick Abel in his experiments referred to in the preceding chapter. On calculating to atomicities the figures there given, we obtain the following: In both series of experiments the composition of the decomposition product of the carbide in annealed steel was the same, namely, C(H2O), or a multiple thereof. T. W. Hogg1 treated one and the same steel (1 per cent. of carbon) in the cast and in the annealed state (in the form of bore turnings) with an excess of dilute nitric acid (sp. gr. 1.2), the vessel employed for the operation being immersed in cold water. In this manner he obtained residues, 1 Journ. Iron and Steel Inst., 1896, vol. ii. p. 179. |
