(231) 
these vessels are covered with shellac, internally with fish-glue. 
Round the paper wall about */, m.m. thick a cotton thread has been 
wound forming a layer also %/, m.m. thick ; while the inner minor 
axis is 12 m,m., the maximum thickness is thus restricted to 15 m.m. 
By means of the conical caoutchouc 
ring c the vessel a is connected to 
the glass tube d, which becomes 
narrower at the top. Onto this the 
brass T-tube e fits, which is connected 
to it by means of a caoutchouc tube. 
Through the caoutchouc stopper g lead 
four glass tubes hj... A4, containing 
the leads for the experimental apparatus. 
For pouring out the condensed gas a 
steel capillary tube k, covered by a 
rubber tube leads through the side-tube 
of e and is screwed on to the above 
mentioned condensing spiral. 
If it is desired to collect the evapo- 
rated gas, all connections may easily 
be made air-tight; for this purpose the 
glass tubes are drawn out at the top 
and the leads may be cemented there. 
Conduits leading to a pump or gas- 
sack can be then connected to the 
side tube of e. 
The T-piece e fits also on the above 
described vacuum-glass and may serve 
to close it, as will be necessary in 
further researches. Untill now there 
was no objection to leaving both baths 
open and allowing the gas to escape. 
In the observation of the HALL- 
effect in an electrolytic plate of bismuth, 
to be mentioned directly, the vessel a 
was about half filled after a small 
quantity of liquid had evaporated. It took more than an hour, 
before the level of liquid was lowered to the opening of 5. In these 
operations about 0.7 kem. of nitrous oxide was used. The space 
between the vessels « and b, the polepieces and the coils of the 
magnet was filled throughout with wool. 
ame Ny 
17* 
