344 
DR. MEYER WILDERMAN OX CHEMICAL DYXAMICS 
the pressure of the atmosphere. The U-tube of the manometer was fixed on a glass 
scale silvered on the back to avoid parallax, the readings of the scale were easily 
made by means of a cathetometer to 0'05 millim.* As the experiments proceeded, it 
was found that there was no possibility of protecting, by means of mercury taps, the 
gas mixture in the quartz vessel from contamination with air for more than a few 
hours, even when to the mercury taps capillary tubes were added containing the same 
reacting gases as the quartz vessel, with a second mercury tap at each end. The 
tubes of the quartz vessel on both sides were sealed for this reason by means of a 
hand blow-pipe as soon as the quartz vessel was filled with the gas mixture. Later 
on the quartz vessel had to be abandoned altogether, chiefly for the reason that it 
could not be heated before filling the reaction vessel with the gases ; more reliable 
results were then obtained with a thin bulb of very pure glass than with the 
quartz vessel. 
Filling the Reaction Vessel with Carbon Monoxide and Chlorine. 
Having read the position of the meniscus of the sulphuric acid and of the mercury 
on both arms of the manometer, the apparatus was exhausted, every part of it being 
heated to expel the air which persistently sticks to the glass walls of the apparatus. 
Since, however, the quartz vessel (owing to the Crookes’ cement and pitch) could not 
be heated, the complete removal of the air was effected as follows :—Having connected 
the pumps through (l) and (2) with (6), the taps (6), (17), (22), (21) and (28) being 
open and the taps (16) and (11) closed, all the vessels (7), (8), (E), (II), (18), (E'), 
(S), (R), (19), (3), (2), (1) and (4) were exhausted first by the Fleuss and then Topler 
pump, and all, except the quartz vessel (II), were heated. The concentrated sulphuric 
acid in (S) and over the mercury in (E) was also heated until no more gas was given 
off. In this way a high vacuum was obtained. The taps (6) and (28) were then 
closed and carbon monoxide passed from its reservoir (15) into the bulbs (S) and (18) 
and to the quartz vessel (II) until the pressure was about 10 centims. The carbon 
monoxide was then removed by exhaustion, (16) and (28) being closed until a good 
vacuum was indicated by the Topler pump, when the vessels were again filled with 
carbon monoxide. This was repeated several times till the air was completely removed 
from the walls of the quartz vessel. Better results, however, were obtained when a 
thin bulb of pure glass was used and the bulb heated during the evacuation. But 
even in this case, after the first evacuation the bulb was filled with carbon monoxide 
* The mercury meniscus in the short arm always remains as clear as a mirror. From its position and 
an ordinary calibration of the capillary tube of the manometer, the variation in the mercury column can 
be determined with even greater accuracy than 0'05 millim. The readings of the mercury meniscus in the 
long arm of the manometer, together with the upper ends of the sulphuric acid columns in the two arms, 
enables the length of the sulphuric acid columns to be measured with an accuracy much exceeding 
0'05 millim. mercury, considering that the specific gravity of the sulphuric acid is only about 1 - S5. 
