Cast Irorif Steely and Malleable Iron, 575 



azote, and the blue tints appeared to me therefore to form a 

 cyanuret of iron (?). 



The gelatinous mass, viewed through the microscope, con- 

 sisted of an aggregation of gelatinous grains of silica, inter- 

 spersed with grains at least ten times smaller of a vermilion 

 colour. The blue layers had the same composition, with the 

 exception, that the silica was penetrated by the before-men- 

 tioned blue colour. 



From these experiments we can perceive very plainly the 

 mechanical structure of the white cast iron, in which the 

 close connexion of the silicon with carbon and azote is beau- 

 tifully developed. 



The disappearance of the blue colour from the layers on 

 the outside during the contact of the acid and the air, shows 

 the progressive formation and decomposition — as well as the 

 interspersed brick-red grains resembling vanadic acid, and 

 explains the mechanical arrangement of the different consti- 

 tuents of cast iron. 



The specimen (6) shows other remarkable qualities. Treated 

 with concentrated hydrochloric or nitric acid, the yellow pow- 

 der, consisting of sulphur and silicon, as already mentioned in 

 a foregoing part of this treatise, was invariably separated : 

 1'80 grains of this yellowish-gray powder, which swam as a 

 viscid mass on the surface of the liquid, heated on platinum 

 foil, lost 0"80 grains of sulphur. The remaining TOO of this 

 yellowish-gray powder, ignited with carbonate of soda, was 

 found to be contracted into a yellowish-brown cake, adhering 

 very strongly to the crucible. Two grass-green drops of man- 

 ganate of soda adhered to the lid ; silica was separated amount- 

 ing to 0*161 1 ; oxide of iron = 0*855 ; alumina =0*028. 



If we consider the sulphur united with the iron, the 

 formula resembles a bisulphuret of iron, and we have 



Silicon 0-077 



Sulphuret of iron . . . 0*945 

 Sulphur 0*800 



1*822 

 or, if we take the ingredients as they appear, 



SiHcon 0*07739 



Aluminum .... 0-01342 

 Iron and manganese . 0*85500 

 Sulphur 0*80000 



1-75081 

 This yellow powder separated was soluble in aqua-regia, as 

 well as in caustic ammonia. 



