162 Proceedings of the Royal Society of Edinburgh. [Sess. 
strip up the side. The outer wall is extended into a ground-glass collar 
with a side tube at the base. A ground-glass stopper fits into the collar 
and the combination is sealed with mercury. Through the stopper which 
is also evacuated passes a capillary ending inside the calorimeter in a 
bulb which holds the charcoal. The gas to be adsorbed is led in 
through the capillary and the heat of adsorption causes evaporation 
of the calorimetric liquid — sulphur dioxide — and the gas evolved is 
collected through the side tube.* 
Fig. 1. 
In Estreicher’s experiments the rate of leak of sulphur dioxide from 
his vessel due to heat passing inwards was about 20 c.cm. of gas per minute, 
but only 5 per cent, of the total gas collected — 2000 c.cm. In the author’s 
case the leak was never more than 4 c.cm., and generally about 2 c.cm., per 
minute, but in some measurements it was as much as 80 per cent, of the 
total gas collected. Estreicher collected the gas evolved in a large 
aspirator containing water with a layer of white oil in which the dioxide 
is not so readily soluble as in water. The author was compelled to sub- 
stitute mercury, as the gas was sufficiently soluble in any oil at his dis- 
posal to interfere seriously with the collection. An oil gauge was then 
used to indicate the pressure. It was now found that the leak appeared 
steadily to diminish. This was traced to cooling of the liquid sulphur 
* The calorimeter was made to the author’s design by Baumbach of Manchester. The 
first calorimeter which subsequently broke was resilvered and evacuated by the author, the 
second by the maker. The rate of leak was less in the first calorimeter. The author is 
indebted to Dr Whytelaw-Gray for many hints as to manipulation here. 
