44 Experiments made on a Sample of Pig Iron 



with hydrochloric acid, decanted again, and residue well 

 washed and dried. A magnet was then passed through it so 

 as to take up any particles of metallic iron which might be 

 left undecomposed. Upon examining the residue with the 

 microscope, peculiar bronze-coloured, star-like crystals were 

 observed. Owing to the large amounts of silica and 

 carbonaceous matter which are left, it is very difficult to 

 separate the little bronze-like stars. These stellate forms 

 contain a large percentage of chromium as a component 

 part in combination with iron. A sufficient quantity has 

 not yet been obtained for a quantitative analysis. This diffi- 

 culty is due to their solubility in boiling hydrochloric acid. 



If they are boiled with nitric acid they lose their bronzy 

 appearance, and become silvery white ; are very slowly dis- 

 solved by this acid. 



They are very slowly acted upon by sulphuric acid. 



Treatment with Nitric Acid. 



Small pieces of pig iron, if boiled with nitric acid, leave 

 silvery white plates. When these appear the acid solution 

 was carefully decanted off* and the plates well washed with 

 distilled water, and re-treated with nitric acid, and boiled. 

 They were washed out into a suitable vessel and dried. 

 These plates are not magnetic, so that any undissolved iron 

 could be removed by a magnet. 



A large proportion of these metallic silvery-looking 

 plates are dissolved, owing to their long-continued boiling 

 in this acid. 



The following are the analyses which have been made of 

 various samples of this compound : — 



(1) (2) (3) (4) (5) (6) 



Percentage of iron 87-44 83-92 84-78 84*60 84-69 84-44 



„ chromium ... 12-71 1607 15-73 15-40 15-90 15-56 



,, carbon trace — — — — — 



100-15 99-99 100-51 100-00 10059 10000 



No. 1. Is the analysis of the first sample of silvery white 

 plates obtained. The plates were not thoroughly freed from 

 undissolved iron, hence the high percentage. 



No. 2. This sample was re-treated for some time in nitric 

 acid, washed well with distilled water, dried, and the magnet 

 passed through the mass, and is therefore the purest sample. 

 The iron and chromium were estimated by a process founded 

 on that given by " Crooke's Select Methods in Chemical 

 Analysis." 



