2C)S Dr, Henry’s Description of an Apparatus for the 
TABLE II. 
Kind of Coal. 
So. of the 
product. 
Weight of 
100 cubic inches 
(Ther. 00 °. Bar. 30 .) 
Spec. Gray. 
(Air jooo.) 
loo cubic inches 
consume 1 give carbonic 
oxyg. gas) acid. 
Wigan cannel. 
I 
24,28 Grs 
733 
234 
1397 
2 
IO 4 
335 
96 
49 
Wednesbury coal. 
1 
2 
20 9 
9 8 
674 
316 
190 
85 
97-5 
46 
Newcastle on Tyne, - 
1 
2 
19 3 
9.8 
622 
316 
190 
86 
too 
45 
Newcastle Stafford- I 
1 
196 
632 
*95 
98 
shire. 
2 
»7 7 
57 ° 
i6 5 
80 
3 
12. 1 
39 ° 
i 00 
60 
I 
I 
20.7 
670 
190 
100 
Leeds, < 
2 
15. 1 
487 
lost by accident. 
r 
3 
9.8 
3 16 
85 
42 
1 
19,4 
627 
1 86 
97 
2 
15 
484 
1 37 
65 
Black-Mine, Lanca- 
3 
"•3 
364 
100 
5 ° 
shire. 
4 
10 
322 
90 
47 
5 
9-5 
3 ° 7 
85 
45 
__ 
6 
80 
40 
1 
12 
387 
11 7 
62 
1 
1 
2 
95 
3°7 
90 
47 
Merthyr, < 
1 
3 
4 
8 
5-9 
261 
190 
' 75 
60 
39 
31 
! 
5 
5.8 
*87 
57 
26 
L 
6 
5-5 
177 
5 ° 
20 
Coal tar. 
- 
24.2 
780 
z 33 
150 
Caoutchouc. 
- 
— 
— 
204 
121 
An attentive examination of the results, contained in both 
the tables, suggests the following general remarks. 
i. The olefiant gas is a very sparing product of the distil- 
lation of pit-coal. It is found only in the first portions, and 
even of these it does not compose more than 5 per cent. Its 
quantity, however, is very much influenced by the temper- 
ature employed. This remark, indeed, may be extended to 
all the aeriform products of coal ; insomuch that from equal 
weights of the same coal it is difficult to obtain by different 
operations conducted on a small scale, products which are the 
