Bibliography. 375 
rature of the same bath in the air. The vapor of carbonic acid, at 
this low temperature, given off from the bath, instead of — a press- 
ure of one atmosphere had only a pressure (tension) of 3; of an at- 
mosphere or 13 inch of mercury. Carbonic acid mixed ‘ih ether is 
not more volatile at this temperature than water at the temperature of 
86° ; the ether was very fluid and the bath could be kept in good order 
for quarter of an hour. Mr. Farapay thinks that these temperatures 
are all about 5° or 6° below the truth. With dry carbonic acid under 
the pump, the barometer attached was raised to 29 inches, while the ex- 
ternal barometer was at 30 inches. Ingentius comer of appa- 
ratus were contrived, by which the condensing tubes could be submitted 
to this great cold under the air-pump receiver in vacuo, and the process 
of condensation examined in progess. 
As many gases condense at a less pressure than one atmosphere when 
submitted to the cold of a carbonic acid bath in air, they were easily 
reduced by sending them through small conducting tubes into tubular 
receivers placed in the cold bath, and by a little management to seal them 
up hermetically in their condensed state. In this manner chlorine, cy- 
anogen, ammonia, sulphuretted hydrogen, arseniuretted hydrogen, hy- 
driodic acid, hydrobromic acid, and even carbonic acid were obtained 
sealed up in tubes, in the liquid state, and euchlorine was also secured 
in a tube receiver with a cap and screw plug. Mr. Appams furnished 
the liquid carbonic acid to Mr. Farapay in portions of 220 cubic inches 
each, which quantity produced carbonic snow enough for an active day’s 
experiments of twelve to fourteen hours; the snow was preserved in a 
triple arrangement of concentric glass cylinders and interposed flannel. 
_ Olefiant gas was condensed by the arrangements described, into a 
clear transparent fluid, but did not become solid even in the carbonic 
acid gas iz vacuo; the pressure of the vapor of this substance at — 103° 
Fahr. is singularly uncertain, being on different occasions and speci- 
mens, 3°7, 8-7, 5 and 6 atmospheres. This irregularity has not yet been 
resolved, but Mr. Farapay suggests that there may be two or more sub- 
Stances physically and perhaps chemically different, in olefiant gas, and 
varying in proportion with the circumstances of heat, proportions of in- 
gredients and attending circumstances. ‘This fluid dissolves resin. 
Hydriodic acid is obtained as a solid at —60° Fahr., and then its vapor 
has a pressure of less than one atmosphere ; ata little higher temperature 
it becomes a liquid, and its vapor has then nearly one atmosphere of 
Pressure. Asa solid it is perfectly clear, transparent, and colorless ; 
ving fissures or cracks in it resembling those that run through ice, It 
dissolves the cap cement and bitumen of the gauge graduation, and ap- 
pears to act on fat as it leaked by the plug of the stop-cock with remark- 
able facility ; it also acts on the brass of the apparatus and the mercury in 
