647 
of Edinburgh^ Session 1865 - 66 . 
of graphite from England, and from the province of Nelson, New 
Zealand, gave indications of the presence of sulphuretted hydrogen 
in the vapour evolved from them by the application of a heat not 
exceeding 300° Fahr. 
In reference to the absorption of gas, it would appear that at 
least carbonic acid does not owe its absorption to the porous nature 
of the coal alone ; for substances quite as porous, such as clay, 
brick, blotting-paper, and wood, when dried at 212° Fahr., and 
placed in carbonic acid gas, did not exhibit any power of absorp- 
tion. A piece of well-washed hydrate of alumina, however, was 
found to be capable of absorbing ten volumes of this gas when 
dried at 212° Fahr., and nearly as much when exposed to a red 
heat ; but as this substance in solution has decided basic properties, 
it is probable the absorption in this instance is due to the exercise 
of these. 
II. Partial Solubility a Property possessed by Coal. 
a. Partial Solubility of Brown Coal. 
h. Partial Solubility of Bituminous Coal. 
Summary of Results. 
From the experiments conducted under this department, it was 
found that a lignite of good average quality, compact and lustrous, 
is soluble in pure water to a considerable extent, — about l-20th per 
cent, being thus soluble, — and that even in the case of a hard, 
compact bituminous coal of excellent quality, belonging to the 
carboniferous formation, this also has a small but very appreciable 
solubility in the same liquid. Allowing this last to be an excep- 
tional case however, it might be argued (if, indeed, lignites are 
in a transitional state between dead vegetable matter and mineral 
coal) that the solubility of the lignite will be continued far into 
the coal proper; but the degree of it will gradually diminish until 
scarcely any method of testing would discover it, or until it be 
finally and completely lost in those members of the coal series 
farthest removed from the commencement. 
4 p 
VOL. V. 
