

92 °* STONY AND METALLINE SUBSTANCES 



The other fhin- The other fhining particles immediately feen, when the in- 

 ing malleable *' ^ erna ^ ftru6ture of the flone is expofed, are the malleable iron, 

 iron, Before I ftate the examination of this iron, I mult remark, 



that preliminary experiments having (hewn me it contained 

 nickel, I treated feveral kinds of the molt pure irons I could 

 obtain, with nitric acid ; and precipitated the oxide from the 

 metallic fait by ammonia. The quantity of oxide I obtained 

 from 100 grains of iron, was from 144- to 146. I may confe 

 quently infer, that 1 00 grains of pure iron acquires, by fuch 

 a procefs, 45 grains of oxigen; and that, whenever a metal- 

 lic fubftance, fuppofed to be iron, does not, under the fame 

 circumftances, acquire the fame proportionate weight, fome- 

 thing is either volatilized, or left in folution. Hence, when 

 a metallic alloy of nickel and iron prefents itfelf, a judgment 

 may, at leaft, be formed of the quantity of nickel, by the de- 

 ficiency of weight in the precipitated oxide of iron. 

 were difTblved In This mode of treatment was not allowed me in the exami- 

 precipitated by nation of the coating of the (tone, becaufe it was impoflible to 

 ammonia, know in what ftate of oxidizement the iron exifted. But, as 



the particles diiTeminated through the whole mafs, are clearly 

 metallic, a very tolerable idea of the quantities of nickel con- 

 tained in them will be obtained, by noting the quantity of 

 oxide of iron feparated, as above defcribed. 25 grains of 

 thefe metallic particles were therefore heated with a quantity 

 of nitric acid, much more than fufficient to diffolve the whole. 

 Some earthy matter, which, as in a former cafe, was not fe- 

 parable by mechanical means, remained after a complete fo- 

 lution of the metal had been effe&ed. This earthy matter, 

 after being ignited, weighed two grains. The real matter of 

 the prefent examination, was therefore reduced to 23 grains, 

 and was in complete folution. I added ammonia to a very 

 fenfible excefs. The oxide of iron was thereby precipitated, 

 and, being collected and ignited, it weighed 24 grains j where- 

 as, according to my experiments, 33| grains mould have been 

 produced from the folution, had it contained nothing but iron, 

 which left nickel I examined the faline liquor, when free from ferruginous par- 

 in triple folution tides, and difcovered it to be the triple fait of nickel. Hence, 

 quantity was ef- a U° wm g f° r M*j tne quantity of nickel may be eftimated, by 

 timated. calculating the quantity of iron contained in 24 grains of oxide. 



Thus, if 145 grains of oxide contain 100 of iron, about 16f 

 are contained in 24 of oxide, This would fuppofe the 23 



grain 



