ELISHA MITCHELL SCIENTIFIC SOCIETY. 41 
bulbs blown in them for catching moisture, etc. <A 
Thérner bath was found to be very convenient for keep- 
ing these flasks at 100° C. The hydrochloric acid was 
prepared by allowing sulphuric acid to drop into a large 
flask containing the hydrochloric acid. The gas thus 
obtained in a regular stream, was passed through a wash- 
bottle coutaininge sulphuric acid and then through towers 
filled with glass beads kept moist with concentrated sul- 
phuric acid. , 
The drying took from fifty to one hundred hours (in 
some extreme cases.) If the stream of gas was rapid the 
temperature could rise to 110° or even higher without 
decomposition of the chloride. A much lower tempera- 
ture caused this decomposition if the stream was insuffi- 
cient to keep the flask full of gas. A number of experi- 
ments were carried out showing these facts. Indeed, two 
in the series of determinations were lost by the stream of 
gas becoming too slow or altogether ceasing for a short 
while. (Experiments VI and VIII.) It was thought 
from experiments at first that where this decomposition 
had begun it was impossible to secure a constant weight 
of the residue, but this is certainly not true where the 
decomposition has been only slight. Of course this intro- 
duces a chance for error in the method. The drying 
must be watched quite closely, and not more than eight 
or ten hours of drying could be easily managed in a day. 
At first it was feared to remove the atmosphere pre- 
paratory to weighing, and efforts were made at weighing 
the flasks full of hydrogen chloride. These results were 
too low and varied among themselves, so that it was evi- 
dently impracticable to carry out the experiments in this 
way. It was found that the hydrochloric acid could be 
replaced by dry air. The flask was removed from the 
bath and dry, pure air passed through it for half an hour. 
It is of course essential that tthe air be carefully dried. 
The tubes were then removed and the glass stopper quickly 
