of the sulfuric acid is greatly increased, provided the temperature
of the reaction mixture is still kept within the limits mentioned.

If a cork is used for the steam distillation of the reaction mixture
of acetone and sulfuric acid, it should be coated well with pitch and wired
into the flask. This is necessary because the vapors of the reaction
mixture attack an ordinary cork very badly, and soften it so much
that it is necessary to rewire it to prevent it from slipping out.
A rubber stopper is satisfactory and may be used in several runs.

The evolution of gas is so vigorous that it is not possible to distil
more than 2 l. of the original reaction mixture at one time
in the apparatus described. The connections on the apparatus,
in which the mesitylene is obtained from the crude reaction mixture,
should be tight, since the fumes evolved during the heating
are very irritating.

The product which distils during the initial heating and the three
minutes of steam distillation is mainly satisfactory material; the rest
of the steam distillation yields only a small amount of pure product.
The two portions of the distillate are, therefore, kept separate,
since the second distillate always contains a considerable amount
of high-boiling product which tends to cause emulsification of
the alkali in the purification. No recovery of acetone is made.

The mechanism of the reaction is undoubtedly as follows:
when the sulfuric acid and acetone are in contact for long periods
of time, several molecules of the acetone condense to form aldol
condensation products. These do not break down into mesitylene until
the temperature is raised in the second part of the experiment.