6 AnultjsiA of the Chroinale of Iron 



left a residue, a part of which was insoluble in water, and 

 weighed, after calcination, only one-half part : it consisted 

 of a mixture of silica and oxide of iron. I now poured into 

 the water which contained the soluble portion of the resi- 

 duum a quantity of ammonia; and a white ilocculent pre- 

 cipitate appeared, which formed with the water a jelly, and 

 exhibited all the characters of alumine : it weighed 10 hun- 

 dredth parts and a half. 



From these experiments on the alkaline solution we may 

 conclude that it contained chrome, alumine, a little oxide 

 of manganese, together with some particles of iron and 

 silica. 



Examination of the ISIuriaiic Solution. 



4. Tl.c colour of this solution, which contained an excess 

 of acid, was reddish vellow. On the addition of a solution 

 of caustic potash a flocculent matter of a brownish red se- 

 parated, which, when washed and mixed with the small 

 (juantitv of oxide of iron already obtained, both from the 

 alkaline solution and from the residue, discovered to be pla- 

 tina. v\cighed, after being calcined, 34 hundredth parts. 



Tlie solution continued still coloured after the separation 

 of the oxide of iron, although the re-agents indicated the 

 presence of no chrome : I was therefore convinced that it 

 owed its tinge to a small quantity of platina. The excess 

 of caustic potash which I had added cojitained some par- 

 ticles of alumine, and these I separated by means of mu- 

 riate of ammonia. 



.5. With a view to ascertain tfie purity of the oxide of 

 iron which had the usual colmu' and appearance of this 

 oxide, I melted it again with pure potash : but water, when 

 added to the mixture, received no tinge, and there-agents 

 indicated the presence of no foreign substance. We must 

 therefore infer that the very weak muriatic acid which I 

 niade use of dissolved nolhinsi' but the oxide of iron. 



From 



