constitution of the prussic and other acids, &c. 227 
for several minutes, then collect into the centre of the mortar, 
what adheres to its sides, and repeat this alternate trituration 
and collection at least six times. 
I then take a tube of glass 4^ inches long, about the size 
of a common writing quill and tolerably stout, I close one end 
of it, and bend the other round, so that nearly an inch of that 
end forms a right angle with the rest. I call this the retort 
tube. I make a second tube similar to the first, except that 
instead of being closed at one end, it is open at both. I call 
this the adapting tube. 
The retort tube is then charged with the mixed materials, 
by means of a small paper funnel, fixed with sealing wax to 
the top of the tube ; the charge is introduced in about three 
equal portions, each of which is separated from the others by 
the introduction of a little coarsely powdered green glass ; the 
charge generally occupies about inches of the tube. After 
its introduction, the wax which fastened the funnel is softened 
by heat, and the funnel detached. 
A graduated glass tube, capable of containing about 
cubic inches, was next filled with mercury, and placed in the 
mercurial pneumatic trough, not in the usual perpendicular 
position, but with its upper end raised, but very little, from 
the horizontal situation, being about an inch above the surface 
of the mercury, while its lower or open end just dipped below 
that surface. In this position, the long leg of the adapting 
tube was passed up into it, which being open at both ends 
became filled with mercury ; the short end of this tube was 
then connected with the short end of the retort tube, by means 
of a caoutchouc tube firmly tied to both. The long end of 
the retort tube when thus disposed, hung over the outside of 
G g 2 
