Sundry Improvements in Apparatus or Manipulation. 245 
flexible tube extending to an air pump, the flasks may be exhausted 
and then closed. A small quantity of water having been previously 
introduced into one of them, if, while: the exhaustion is sustained, 
the other flask be refrigerated by ice and salt, the water will be 
frozen.* 
The intelligent chemist will perceive that this apparatus may be 
applied to the purpose of desiccation by placing the article to be 
dried in one receptacle, and quick lime, chloride of calcium, or con- 
centrated sulphuric acid in the other. ‘The orifice of the receptacles 
may be made larger without inconvenience. ‘Two large cylinders, 
for imstance, may be used. 
I propose, as soon as J have leisure, to apply the principle illus- 
trated by this apparatus, to the distillation or desiccation of many 
substances which are liable to injury when exposed to heat or air. 
I conceive that there is, by means of analogous apparatus, a fruitful 
field for improvement in the arts. I conceive that it may be em- 
ployed in the preservation of meat, milk; fruit, vegetables, and the 
making of cheese ; also in pickling and preserving. 
* For the information of readers who may not be chemists, I subjoin the follow- 
ing explanation of the cause of the congelation of the water. 
So long as no condensation is effected, of the thin aqueous vapor, which, when 
-water is present, must occupy the cavity of the instrument, that vapor prevents, by 
its pressure, or tension, the production of more vapor: but when by means of cold 
the vapor is condensed in one bulb, its evolution in the other, containing the water, 
being unimpeded, proceeds rapidly. Meanwhile, the water becomes colder, and 
finally freezes, from losing the calorie which the vaporization requires. 
According to Wollaston, one grain of water, converted into vapor, holds as 
much caloric as would, by its abstraction, reduce thirty one grains from 60° F. to 
the freezing point; and the caloric requisite to vaporize four grains more, if ab- 
stracted from the residual twenty seven grains, would convert them into ice. 
Vou. XX XITI.—No. 2. 32 
