Cast Iron, Steel, mid Malleable Iron. 431 



grains in weight during ignition, we may conclude, that the 

 black spots consisted of metallic silicon, which had become 

 oxidized into silica during the process. 



The solution had a greenish-yellow appearance, and after 

 being concentrated by evaporation and diluted with distilled 

 water was mixed with carbonate of magnesia. The precipi- 

 tate dissolved in hydrochloric acid and again precipitated 

 with succinate of ammonia, yielded 2*50 oxide of iron = 

 1'7335 metallic iron ; no manganese could be discovered. 



The filtei-ed liquid now held in solution the protoxide of 

 iron. Digested with nitric acid, precipitated with ammonia, 

 ignited, dissolved again and freed from magnesia, it yielded 

 oxide of iron = I'lOO = 0'8901 metallic iron. This method 

 of separating the protoxide of iron from the peroxide is not 

 sufficiently accurate, and I mention this part of the process 

 only to show that the iron, even after ignition, remained in 

 the state of protoxide mixed with peroxide. Having tried 

 to ascertain the amount of protoxide and peroxide of iron in 

 these solutions as accurately as possible, by converting the 

 peroxide of iron by means of solution of sulphuretted hydro- 

 gen into protoxide, and ascertaining the quantity of separated 

 sulphur &c. in one part of the solution, and mixing another 

 part with liquid chloride of gold and sodium, — from the quan- 

 tity of the reduced gold the quantity of protoxide of iron was 

 very easily calculated, and I obtained for the greatest part 

 proportions which approached to a rather strange formula, 



3F + 2F. The carbon taken away by the escaping hydrogen is 

 of far less amount than is generally asserted; and each atom 

 of carbon volatilized in this way is at the same time replaced 

 hy oxygen or sometimes hydrogen. 



The remaining part of the brown powder, = 3*39, was like- 

 wise put into a platinum crucible, heated like the first over 

 a spirit lamp, till it began to glow on the periphery, and then 

 quickly removed from the fire. The first smooth surface of 

 the powder on the bottom of the crucible was now found to 

 be intersected by small cracks, through which might be seen 

 the interior of the powder in ignition for some time; its colour 

 after cooling became darker, but it had neither gained nor 

 lost in weight. 



Hydrochloric acid of 1*16 sp. gr. did not visibly attack 

 this powder; but heated in a sand bath, the action of the acid 

 became at once very lively; a great quantity of hydrogen 

 smelling slightly in the well-known way was disengaged, and 

 a velvety black residuum of a rather oily appearance was 

 left. 



