548 Royal Society :— 
depth of inspiration. A decrease in quantity was caused by sp. 
ammon. co. (3iss), sp. ammon. feet. (3iss), tincture of opium (20M), 
morphia (4 and + gr.), tartarized antimony (4 gr.), and chloride of 
sodium. 
Carbonate of ammonia (15 grains) caused a small increase at first 
and then a small decrease; febrifuge medicines had a like effect. 
Chloroform (25m and 3ss), by the stomach, varied the quantity 
from an average increase of 28 cub. ins. to an average decrease of 
20 cub. ins. per minute; with a maximum increase of 63 cub. ins. 
per minute. Chloric ether (3ss) also varied the quantity, but there 
was an average increase of 17 cub. ins. per minute, and of 1:8 per 
minute, in the rate; whilst the pulse fell on the average 1*7 per min. 
Chloroform, by inhalation (to just short of unconsciousness), lowered 
the quantity a little during the ihalation, and more so afterwards. 
The rate was unchanged, but the pulse fell, on an average, 1*7 per 
min. Amylene similarly administered and to the same degree, 
increased the quantity during inhalation 60 cub. ins. per min., but 
afterwards decreased it to 100 cub. ins. per min. less than during 
the inhalation. The rate of respiration was unchanged: the pulse 
fell 6 per min. at the end of the observation. 
Digitalis (infusion Zi) varied the quantity, increasing it at first 
and then decreasing it. The rate of inspiration was unaffected, 
whilst that of pulsation somewhat-increased. 
The paper is accompanied by tables of numerical statements, and 
by diagrams exhibiting the results in a series of curves. 
May 7.—The Lord Wrottesley, President, in the Chair. 
The following communications were read :— 
“On the Plasticity of Ice, as manifested in Glaciers.’ 
Thomson, A.M., C.E. Belfast. 
The object of this communication is to lay before the Royal So- 
ciety a theory which I have to propose for explaining the plasticity 
of ice at the freezing-point, which is shown by observations by Pro- 
fessor James Forbes, and which is the principle of his Theory of 
Glaciers. 
This speculation occurred to me mainly in or about the year 1848. 
I was led to it from a previous theoretical deduction at which I had 
arrived, namely, that the freezing-point of water, or the melting- 
point of ice, must vary with the pressure to which the water or the 
ice is subjected, the temperature of freezing or melting being lowered 
as the pressure is increased. My theory on that subject is to be 
found in a paper by me, entitled ‘‘ Theoretical Considerations on the 
Effect of Pressure in Lowering the Freezing-Point of Water,” pub- 
lished in the Transactions of the Royal Society of Edinburgh, vol. xiv. 
part 5, 1849*. Itis there inferred that the lowering of the freezing- 
point, for one additional atmosphere of pressure, must be °0075° 
Centigrade ; and that if the pressure above one atmosphere be denoted 
in atmospheres as units by 2, the lowering of the freezing-point, 
be 
By James 
* The paper here referred to is also to be found in the Cambridge and Dublin 
Mathematical Journal for November 1850 (vol. v. p. 248), where it was repub- 
lished with some slight alterations made by myself. 
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