452 Scientific Proceedings, Royal Dublin Society. 
open end of the stop-cock, and by turning the latter, is filled with 
mercury. 
The end of one of the sealed tubes, C, is then pushed down 
into this tube until it is firmly attached, and the sealed tubé 
clamped vertically to the retort-stand. 
The receiver D containing the air sample is next clamped in an 
inverted position above the upper end of the sealed tube and 
attached to the latter as shown, care being taken when making the 
attachment that the india-rubber junction connected with the 
receiver is pinched between the finger and thumb, both when 
removing the glass rod plug and also when inserting the end of 
the sealed tube. Both ends of the latter are then broken off 
within the rubber junctions; and lastly by slowly turning the 
stop-cock, the contents of the sealed tube are gently driven into the 
receiver. ‘The stop-cock is then closed, and the receiver detached 
and plugged (with the same precautions as before for preventing 
access or egress of air) ; then rolled round to spread the absorbent 
over its inner surface, and allowed to remain at rest during the 
period necessary for absorption. Meanwhile the tube previously 
containing the absorbent remains filled with mercury. 
In order to make the re-transfer of the absorbent from the 
receiver to the tube, the receiver is clamped to the retort-stand in 
the same position as it occupied before, the same attachments made, 
and the solution withdrawn from the receiver by first lowering 
the mercury reservoir, and then slowly opening the stop-cock until 
a little air makes its way into the upper end of the sealed tube. 
The receiver is then removed, and the upper end of the tube sealed 
off. The tube is then inverted, its lower (now its upper end) 
detached, and also sealed off. We prefer this method, but another 
one may also be employed. 
Method 2.—To the receiver containing the air sample two 
lengths of thick-walled india-rubber tube are attached, the longer 
to B and the shorter to A (fig. 6). 
Both of these contain the air sample to be examined (the 
volume of which is added to the capacity of the receiver in 
the subsequent calculation); and previous to the absorbing 
process the ends of these two are plugged with short pieces 
of glass rod. They replace, in fact, the short plugs previously 
described. 
