4?28 Dr. Schafhaeutl on the Different Species of 
The contents of the test glass poured on a filter were care- 
fully washed with ammonia, and the liquid afterwards evaporated 
to dryness in a platinum crucible. This dry remainder was 
perfectly white ; only in the corner of the crucible some brown 
matter was collected, in all probability a species of humine. 
This dry residuum weighed 0*3 grains, was after ignition 
perfectly white, and had lost 0*08 grains. It dissolved in 
hydrochloric acid, left silica behind, which I was unable to 
weigh, and carbonate of ammonia threw down alumina mixed 
with some silica. 
In consequence of this, 5*53 grains would have contained 
aluminum equal to 0*298793 grains. To account for 0*0188 
hydrogen we ought to have 0*440893 aluminum. By actual 
analysis I found 0*352583 ; but it might very well have hap- 
pened that, in separating alumina from phosphoric acid, a 
part remained combined with the acid. 
The gray residuum which had been treated with ammonia, 
dried and weighed, was 1*82, and had therefore lost 0*28 grains, 
that is to say 0*02 grains less than the weight of alumina ob- 
tained. This extraordinary evolution of hydrogen takes 
place with all residuums of hot-and cold-blast gray iron, but 
with the former more than the latter; and perfectly white iron 
never evolves any gas whatever ; yet white iron which is 
nearly approaching to gray iron gives always traces of hy- 
drogen. 
What causes this extraordinary decomposition of water ? 
We know no other chemical body which, left as a residuum 
after being treated with acids, possesses the power of decom- 
posing water by the presence of ammonia, except aluminum ; 
and as the ammonia had really dissolved alumina, which only 
occurs when it comes in contact with the metallic base of alu- 
mina, we may safely conclude, that the extraordinary evolu- 
tion of hydrogen was here produced by the presence of me- 
tallic aluminum. 
Solution of caustic potash ley likewise decomposes the gray 
residuums, but only at a higher degree of temperature, and 
then a species of slight explosion takes place and the fluid is 
thrown with some violence out of the crucible. 
Viewed through a microscope, the residuum of this gray cast 
iron appears to be composed of white gelatinous transparent 
nodules, which generally surround a centre, consisting of some 
dull black spots and of a scale, sometimes shining like graphite, 
but of a more silvery whiteness. The mixture of these scales 
with the white nodules gives the powder, to the naked eye, the 
appearance of having a grayish colour ; these scales remain 
after being treated with ammonia, though not at all apparently 
