|g3 ^^ THB OXIDES or r»ojri 



of mercury. He found, that in these two iVimiiR tliflr woif 

 increased from 35 to 40 per cent. In the table whlc'h follows 

 his paper he gives the increase of iron by avsirtiic at 30 of 

 oxigcn to 100 of metal ; and in hi3 Eleiaentar}^ Treatise of 

 Chemistry he quotes au experiment, in which iron treated 

 with oxide of mercury gained 32 per cent. 

 Ko accurate It is not easy to deduce from these experiments any po&i- 

 ^"JniwnVrora ^^^^ conclusion res|>ecting the proportion of oxigen in. the 

 ^e&«. two dei^rees of oxidation, because, 1st, the quantities df 



oxigea combined vary too much : 2dly, the state of the 

 oxide after oxidation was not accurately ascertained : 3<i\f* 

 it is not certain, that the arsenic, which has a great affinity 

 for iron, did not carry away some of it when volatilized. It 

 appears too, that Guyton, in his experiment, did not mix 

 a, fcufficient quantity of oxide of arsenic with the iron ; for, 

 according to t]m experiments of Proust*, the white oxide of 

 this metal contain but 33 of oxigen to 100 of arsenic; 

 whence the 100 parts of oxidecould only have yielded about 

 t25 of oxigen to the iron. 



ManUl eih 



op ft. 



4th Method, Oxidation of ironby water. 



Oxidafyia of T'he black oxide has long been prepared in the shops, 

 »f«" ^y ^■'»tc''' nhder thename of martial ethiops, by putting iron filing* 

 into a bottle full of water, shaking the niixlure from time 

 to time, and opening the bottle after every shaking, to let 

 out the hidrogen gas evolved. To accelerate the process*, 

 Rouelle proposed to acidulate the water with vinegar, 

 Crohaic with a, little witricacidf, 



Lavoisier found, that iron filings gained an increase of 

 30 or 35 percent by agitation in pure water ; and the same 

 if the water were acidulated^. 



Cavazzely, on oxiding iron by means of water, obtained 

 an oxide increased 35 per cent on theiron employed§, 



Bucholz, repeating ^he 4Jxperiment of oxidation by 

 water alone at the common temperature of the atmosphere. 



LaTuibier. 



CftTJizzely. 

 Buchalz. 





• Journ. de Pbys. 1799, torn. II, p. 150. 

 t Ana.ji^ChUn. vol. XXXI, p. S33andfol. 

 X Ac. des Sciences, 1 782, p. 543 and fol. " 

 ^ Ann. 4e Chim. vol. XLIJI, p. 94. 



remarked. 



