78 



stimulate the endeavours of philosophers, and particularly of chemical 

 analysts. 



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 Abbe Bachelay and Professor 

 Barthold, who by making their experiments only upon the stones in 

 the aggregate, obtained of course none but fallacious results. 



The Benares 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, described by Mr. Hermstadt as an ammoniacal nitrate of nickel, 

 which 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 1 6 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 tiie mass in small globules. Having reason to suspect 

 tiiat 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 indication : Finding that 100 grains of pure iron 

 would yield about 145 grains of oxide, it would be a certain proof that 

 the metal contains something 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 tiie 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 2^ 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 1 ^ grain ; this is 

 ascribed to the oxidizement of the iron. 



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



