ANALYTIC PROCESSES 17 
continuous extraction apparatus devised by 
Szombathy, but commonly called the Soxhlet 
tube, is most suitable. 
The material may be placed in a fat-free paper 
thimble and covered with a plug of cotton to 
prevent loss of fine particles. In place of the 
cotton plug, a porcelain or platinum Gooch 
crucible may be used, as shown in the cut. 
The top of the thimble should be a short dis- 
tance below, and the top of the crucible a short 
distance above, the bend of the siphon. The 
thimble should be supported by a section of 
glass tubing, 1 to 2 cm. long, with rounded 
edges; the edge on which the thimble rests should 
be a little uneven to prevent a close joint, which 
would hinder the siphoning of some of the 
liquid. 
Alundum cylinders will probably be useful. 
Loss of solvent by leakage often occurs. It 
may be diminished somewhat by soaking the 
corks in rather strong hot gelatin solution, 
draining them quickly and then exposing them 
for some hours to formaldehyde vapor. 
The solvents most generally employed are 
ether and petroleum spirit, but carbon tetra- 
chlorid is well adapted for extraction purposes 
as it has high solvent power for fats and is not 
easily inflammable. 
When extraction is completed, the carton and 
