Lerts & Brake—The Carbonic Anhydride of the Atmosphere. 128 
sample to be examined. The india-rubber tube was then removed 
and the receiver plugged. 
Before adding the absorbent, the glass rod plugging I. was 
replaced by a soda-lime tube, the rubber junction being pinched 
between the finger and thumb during the operation, to prevent 
access of air. The rod attached to II. was then removed with the 
same precaution, and its rub- 
ber junction attached to the 
pipette for delivering the 
charge of baryta solution, 
which latter was then run in. 
The glass rods were then re- 
placed with the same pre- 
cautions as before, to prevent 
access of air; the receiver 
shaken with a rolling motion, 
so as to thoroughly wet all 
parts of its inner surface, and 
left on its side for some hours. 
It may be mentioned that 
the capacity of the receiver was 
ascertained by measuring the 
'50c.0 
volume of water required to 
fill both it and the attached 
tubes, and that it was of course 
necessary to subtract from this 
volume that of the absorbing 
Fig. 2.—Baryta Stock Borris. solution added, in making 
A.—Paraffined bottle containing the baryta the calculation of the amount 
solution. of carbonic anhydride present 
B.--Soda-lime tube. : : ° 
C.—Pipette holding 50 c.c. in theair. It is scarcely neces- 
D.—Glass stop-cock connecting the syphon Z . P c 
ae ee sary to add, that a reading of 
F.—Air-tube. barometer and thermometer 
G.— Pinch-cock. 4 d A hs 48 f 1] 
H. 1. F.—India-rubber corks. was made a e time of Col- 
lecting the air sample. 
Baryta stock-bottle and measuring pipette. —'The stock-bottle 
for holding the supply of standard baryta solution contained 
about 1 litre, and was coated on the inside with paraffin wax in 
precisely the same way as the receivers—so alsc was the lower 
SCIENT. PROC. R.D.S,, VOle IX., PART II. ~ L 
