515 
Cast Iro7iy Steel, a?id Malleable hon. 
After boiling for more than twenty-four hours, 20*4 grains 
left a dark-green residuum, weighing only 2*64 grains, and 
this residuum burnt in a dried stream of air in a horizontal 
glass tube, blackened with the first action of heat, and drops 
of water collected on the upper part of the tube. After the 
water was driven into its receiver, brown spots remained on 
the glass ; the drops of water collected smelt as if impregnated 
with tobacco-smoke, and the gas which escaped from the ap- 
paratus for collecting carbonic acid had the same smell, 
I collected carbonic acid 0*954 : water 0*238 : and there 
remained white silicon = 2*35. 
For 0*954 carbonic acid is = 0*2637810 carbon; and 0*238 
water is = 0*0263942 hydrogen. Sum of carbon and hydrogen 
0*2901752, This last amount is only less 0*1998848 grain and 
to account for the loss of carbon, hydrogen and azote which 
passed through the bulb glass containing the caustic ley in 
the form of the before-mentioned nicotianic gas. 
By boiling the residuum of white iron for a short time only 
in hydrochloric acid, very little iron is dissolved, and the 
remainder assumes a greyish colour, and becomes white or 
grey after the first ignition without first glowing like tinder. 
By boiling it with caustic alkalis only traces of silica are 
extracted, whilst a species of brownish humus was dissolved, 
which I found never to exceed in amount 2 per cent. ; the silica 
therefore must be contained in a chemical combination with 
carbon, azote and iron. 
A short ignition of the residuum on the contrary is suffi- 
cient to make the greatest part of the iron soluble in acids. 
If it is only heated, till it begins of itself to glow, the iron is 
dissolved by acids, and the evolution of hydrogen shews that 
the iron must be contained in a metallic state in the residuum. 
When, on the contrary, this remainder is heated as long as it 
absorbs oxygen, and then treated with acids, no evolution of 
gas takes place, and a mixture of protoxide and peroxide of 
iron is dissolved. 
As soon as this residuum begins to glow, carbonic acid, 
azote and a little hydrogen are invariably evolved, which 
shows the intimate connexion between the solubility of the 
iron and the carbon, azote and hydrogen in the residuums. 
Not only the evolution of hydrogen gas, but the powerful 
action on the magnet, proves, that the iron in these residuums 
must be contained in the metallic state. Even were we to con- 
sider it as protoxide, the great increase of weight, that is, the 
absorption of oxygen, which takes place during ignition, could 
not be accounted for. But as the iron, notwithstanding its 
metallic state, is not soluble in acids before ignition, we must 
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