134 Proceedings of Royal Society of Edinburgh. [sess. 
of weight of the tubes ; as a rule, it is decidedly less. In so 
complex a substance as a deep-sea mud it is impossible to account 
for this in detail ; but organic matter, which is never absent from 
such muds, would, by its oxidation, increase the weight of the tubes 
at the expense of the air, while the oxidation of the fixed com- 
ponents, such as ferrous oxide, would have a like effect on the 
ignited mud. The figures, therefore, in the Table give a complex 
result, from which it is impossible to isolate the separate items. It 
is evident, from the general agreement of the figures, that the drying 
process (Table II.) has brought the various samples into a very 
fairly comparable condition. 
Table IY. Determination of the Carbonic Acid. — A weighed 
quantity of the substance was placed in a flask and sulphuric acid 
added. The carbonic acid was collected in soda-lime tubes, being 
first dried by passing it through a U tube filled with pumice, 
moistened with concentrated sulphuric acid, and a tube filled with 
calcium chloride. 
Tarle IV. — Determination of Amount of Carbonic Acid. 
No. of 
Sample. 
Weight 
of Sample 
taken 
(grammes). 
Weight of C0 2 
absorbed by 
1st Soda-lime 
Tube 
(grammes). 
Weight of C0 2 
absorbed by 
2nd Soda-lime 
Tube 
(grammes). 
Total 
Weight of 
C0 2 
(grammes). 
Per cent, 
of 
co 2 . 
Per 
cent. 
of 
CaC0 3 . 
a 
b 
c 
d=b+c 
e = ioo | 
/ 
31 
1*7395 
0*1396 
0*1396 
8*037 
18*3 
32 
1*1346 
0*0987 
0*0987 
8*10 
18*4 
35 
1 *5251 
0*1268 
0*001 
0*1269 
8*38 
19*1 
36 
1*5970 
0*1385 
0*0006 
0*1391 
8*71 
20*0 
39 
1*0160 
0*1083 
0*0017 
0*1100 
10*83 
24*5 
41 
1*3468 
0*1238 
0*1238 
9*19 
21*0 
43 
1*5683 
0*1600 
0*1600 
10*10 
23*6 
45 
1*3200 
0*1853 
0*0002 
0*1855 
14*05 
32*4 
46 
1*2864 
0*2165 
0*0009 
0*2166 
16*82 
38*2 
64 
1*1379 
0*2378 
0*2378 
20*90 
47*1 
65 
1*8921 
0*3129 
0*3129 
16*08 
36*6 
86 
1*2456 
0*1767 
0*1767 
14*19 
32*5 
87 
1*4305 
0*1909 
0*1909 
13*34 
30*8 
88 
1*5087 
0*2131 
0*2131 
14*12 
32*5 
89 
1*4595 
0*2024 
0*2024 
13*87 
31*8 
The flask was boiled to expel the gas, and a current of air, free 
from carbonic acid, was drawn through the apparatus to sweep out 
all the carbonic acid. 
