152 Proceedings of Royal Society of Edinhurgli. [feb. 6, 
superintended the physical part of these experiments with cha- 
racteristic patience and kindness. 
This subject does not seem to have been previously investigated. 
Th. Schloesing and others have demonstrated that the solubility 
of carbonate of lime, &c., in water containing carbonic acid, 
increases as the pressure of carbonic acid increases, and that 
according to a definite law ; but nothing is 
said about the effect on the solubility, when, 
the quantity of carbonic acid in solution 
remaining the same, the pressure is in- 
creased. The latter was the object aimed at 
in these experiments, and as they had special 
reference to the conditions existing in the 
ocean, sea water was taken and charged 
with a definite quantity of carbonic acid, 
that the effect might be exaggerated, and 
therefore more easily studied. 
Tor the experiments done under pressure 
the following modus operandi was adopted: — 
A (see sketch) is a Bohemian glass funnel, 
having a glass cover ground to fit; a flat 
india-rubber band of the same circumference 
as the cover is put between it and the funnel. 
A rubber capsule is now stretched over the 
top, and for greater security the neck of the 
funnel is passed through a slit in a strong 
rubber band, which is then stretched over the 
capsule. The funnel contains a filter paper, 
and a cambric bag, within which is a weighed 
quantity of shells. To the funnel the bulb 
B is attached, and this is connected by the 
glass tube C to a vessel containing mercury D. 
The whole is tied to a suitable support, and 
is ready for immersion in the water, contained 
in the pressure apparatus, i.e., the celebrated “gun” belonging to 
the “ Challenger ” Commission. The bulb B, which has been accu- 
rately measured, contains sea water charged in the following manner 
Avith a definite quantity of carbon dioxide. B is first filled with sea 
