Page:Proceedings of the Royal Society of London Vol 1.djvu/98

Rh stimulate the endeavours of philosophers, and particularly of chemical anal sts.

III. The foremost among these was Mr. Howard, who, in the third part of his paper describes the several methods by which he examined each of the constituent parts of these stones separately, avoiding thereby the mistakes of the Abbé Bachelay and Professor Barthold, who by making their experiments only upon the stones in the aggregate, obtained of course none but fallacious results.

The Benarcs stone being, as Count de Bournon had already men. tioned, the most characteristic, was the ﬁrst he undertook to examine. In analysing the crustaceous matter, in which some nickel was soon found to be contained, the process led to an investigation of the triple salt, desoribed by Mr. Hermstadl: as an ammoniacal nitrate of nickel, ivhich was soon found to be a proper menstruum for discovering the presence of the last-mentioned metal. The presence of iron and nickel was manifestly discovered in their substance; but the quantity that could be obtained was so small that it was found impracticable to give the proportions of their constituent parts.

The pyritical part was next examined. The result of the analysis, the particulars of which cannot be abridged, was, that 16 grains con- tains iron 10-} grains, sulphur 2 grains, nickel nearly 1 grain, and extraneous earthy matter 2 grains : half a grain appears to have been lost in the process, owing probably to the impossibility of re- ducing the sulphur to the same degree of dryness as it existed in combination with the iron. The weight of the nickel, too, is a mere estimation, our acquaintance with that metal being as yet too imper- fect to speak of it with accuracy, except as to its presence.

The third substance Mr. Howard examined was the native iron disseminated in the mass in small globules. Having reason to suspect that some nickel was likewise contained in this substance, he con- trived an expedient for estimating its proportion, of which the fol- lowing is a slight indicationz—Finding that 100 grains of pure iron would yield about 145 grains of oxide, it would be a certain proof that the metal contains someﬂaing which is either volatilized or left in the solution, if. under the same circumstances, it do not acquire the same proportionate weight. Hence when a metallic alloy of nickel and iron in known proportions is digested in nitric acid, it is plain that the de- ﬁciency of weight in the precipitated oxide of iron will be propor- tionate to the quantity of nickel contained in the alloy. By this means 25 grains of these metallic globules, being freed from earthy and other extraneous matter, left 23 grains of alloy, which were found to con- sist of 14 grains of pure iron, and .9 of nickel.

The small spherical bodies, equally dispersed throughout the mass, were the fourth objects of inquiry. The result of this analysis was, that 100 grains of the substance was decomposed into 50 silica, 15 magnesia, 34 oxide of iron, and 215 oxide of nickel. By summing up these it will be found, that instead of the loss usual on these occasions, there was an excess of weight of 1½ grain; this is ascribed to the oxidizement of the iron.

Lastly, the earthy matter, forming a cement or matrix for the sub-