a 
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by Carbon Dioxide. 195 
deflection which was noted by the observer. The tube being 
then filled with carbonic acid, which on account of its specific 
gravity could not escape, a smaller deflection was obtained, 
indicating a certain absorption in a column of gas double the 
length of the tube. It remains to describe the way in whic 
the filling was accomplished. 
short glass tube passing up by the mirror through the 
generator or with a water air-pump in an adjoining room. The 
generator consisted of a bomb containing eight kilograms of 
pure liquid CO,, from which a practically inexhaustible supply 
of gas could be drawn and the tube filled in as short a time as 
desired. By disconnecting the generator and connecting the 
air-pump the gas was withdrawn from the tube and ejected 
from the room. 
end of a wooden splinter, for which purpose a small offset tube 
had been provided, branching off from the large one near the 
top. In order to prevent air currents from disturbing the level 
of the gas, the mouth of the large tube was covered during the 
to flow to supply the loss by diffusion, and several observations 
made as before with the galvyanometer. These deflections 
were, in the case of the lamp, somewhat smaller than the first. 
The tube was then connected with the pump and the observa- 
tions continued, the deflections increasing as the level of the 
CO, sank in the tube, and regaining their original value when 
the gas was all out. 
s an example, I give the record of observations made on 
the 15th of March, the source of heat being in this instance the 
non-luminous flame of a Bunsen burner. 
~ Am. Jour. capgiicacagss Series, Vout. XXVIII, No. 165.—Sppt., 1884. 
