32 
PURIFICATION OF SULPHURIC ACID. 
position, that the first part of the neck may incUne towards 
the body of the retort. 
The reason of this, which is an observation appUcable to 
the distillation of liquids generally, is, that when a hquid 
is in a state of ebullition, if it be looked at horizontally at 
the level of the surface, small drops are sometimes seen pro- 
jected above the surface, forming curves of greater or less 
extension. All liquids, in boiling, do not exhibit this phe- 
nomenon ; but as sulphuric acid does, it follows, conse- 
quently, that during the operation, and especially if the re- 
tort be too full, a great number of these drops are thrown 
into that part of the neck which is near the body of the 
cucurbit. This part of the neck should, therefore, be inclined 
in such a manner, as to favour the return of these drops 
into the cucurbit, which, without this precaution, would 
run over, and mixing with the distilled liquid, render it im- 
pure. Currents of cold air, also, cannot be too much guarded 
against, which otherwise striking against the neck of the 
retort, would be likely to cause a fracture. Every time 
that my retorts have been broken in distilling sulphuric acid, 
the accident has happened in this way. — Pharm. Journ., 
from Journ. de Pharm, 
