Cast Iron^ 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 TOG 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*1611 ; 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, 
Silicon 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. 
