2 94> Hr. Henry’s Description of an Apparatus for the 
on coal and a few similar substances, reserving the rest for a 
future communication. 
Gas from Cannel Coal. 
This was received in two separate portions. Of the first 
product, 100 cubic inches, corrected to a mean temperature 
and pressure, weighed 24.28 grains. Hence its specific 
gravity was to that of atmospheric air as 783 to 1000. The 
second product was much lighter, 100 inches weighing only 
10.4 grains, and having, therefore, the specific gravity of 
335. The results are comprehended in the following table. 
The carbonic acid, stated to have been generated by the second 
combustion, was formed by adding to an aliquot part of the 
residue, after the removal of the carbonic acid, a proportion of 
hydrogen gas ; detonating the mixture by the electric spark ; 
and proceeding as already directed. The two first lines con- 
tain the minutes of actual experiments ; the third and fourth 
these results reduced to centesimal proportion. 
Sp. Grav. 
Cub. inches 
burned. 
Oxyg. gas. 
consumed. 
Carb. acid, 
generated. 
Carb. acid 
formed by 
second com- 
bustion. 
Oxygen con- 
sumed by 
second com- 
bustion. 
Total oxygen 
consumed. 
Total, carb. 
acid formed. 
783 
7-3 
16.5 
8-3 
1.9 
0.9 
17.4 
10.2 
.335 
9.8 
94 
4.8 
O 
O 
9.4 
4.8 
783 
100 
222 
1 13-7 
2.6 
12 
234 
1397 
335 
100 
96 
49 
0 
O 
96 
49 
The early product of the gas from cannel coal, before 
being washed with lime water or caustic potash, is a mixture 
of several different gases, viz. carbonic acid, sulphureted 
hydrogen, olefiant, and a fourth, which is either a gas sui 
generis , or a mixture of carbureted hydrogen, and. carbonic 
oxide,, To ascertain the proportion of these gases in any 
