302 British Association for the Advancement of Science. 
instruments are used two gauges of observation,—one to show 
when the generator is filled with water by the pumps, and con- 
_ sequently all the free carbonic acid forced into the receiver ; and 
the other to determine the quantity of liquid acid in the receiver. 
A table of the elastic force or tension of the gas, over the liquid 
carbonic acid was shown for each ten degrees of the thermometer, 
from 0° to 150°. The following are some of the results :. 
Degrees. ~ Ibe per square inch. * ~ Atmospheres of 15 Ibs. each. 
ay oe. ne RIND este eta Sh A POR et 
46 2 sgiess - 300 that - 20 
20 deitietsneeh ace oRMBD aly Hier Reus hr B6.64 
BR, Kerk xe mtis ANS Agee nh. ho 27.06, 
si BBO osc en ueer 620.05. yee «2 > BLOT 
AON sere er ot MRER ec = t+ | 62.32 
150 snes >= 0-7 1406.65 - + - = 99:71 
Mr. 7.4 Cinedtdi to examine the pressure at higher temperatures, 
up to that of boiling water and above; and he ‘assorted his belief 
that it may be profitably employed as an agent of motion,;—a sub- 
stitute for steam,—not directly, as had been already tried by Mr. 
Brunel,—but indirectly, and as a means to cireulate or recipro- 
eate other fluids. ©The solidification of the acid was shown, and 
the freezing of pounds of mercury in a few minutes, by the cool- 
ing influence which the solid acid exercises in passing again to 
the gaseous state. 
. T. Thomson communicated ‘a a paper on the foreign sub- 
stances contained in Irom. erage dictate ppees mic 7 
phosphorus in very minute quantities. - 
Prof. Johnston read a paper on some iteniions to the law of 
Isomorphism, showing that substances crystallizing in the same. 
form were not always composed of the same formule. 
Dr. R. 
D. Thomson and Mr. T. Richardson presented a com- 
munication on the decomposition net by the action of E'mul- 
sin on Amygdalin. — 
A paper was offered by Mr. Exley, on Chemical combinations 
produced in virtue of the presence of bodies which remain to con- 
tinue the process. It has been observed, said Mr. E., that in ma- 
ny instances, powerful chemical affinities have been brought into 
activity by the presence of certain bodies which remain insulated. 
This Berzelius attributes to a peculiar force, which he calls cata- 
lytic force. Several reasons are adduced to show that this force is 
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