on Spi rituoits L i quors . 43 1 
3. The difficulty, or almost impossibility, of bringing the mix- 
ture, by the repeated fillings, to coincide exactly with the ring on. 
the neck : for this purpose, the last quantities of water must be 
put in by such small portions at a time, that scarcely any atten- 
tion will be equal to the task ; and if at length too much be added, 
it cannot be taken out again without injuring, in some degree, 
the accuracy of the experiment, which depends on combining 
the precise quantity of water required to fill the vessel up to 
the mark, when the full penetration has taken place. 4. In 
opening the vessel so frequently, to fill it up, a sensible part 
of the spirit must be lost by evaporation. 5. Moreover it is 
necessary that, at the end of the operation, the fluid should 
throughout be exactly of the same temperature as the pure 
spirit was in the preparatory experiment with it alone ; the 
difficulty of effecting and determining which must be obvious 
to every one, especially in a vessel of such a size and shape. 
Lastly, as this vessel is much less manageable than the weigh- 
ing-bottle, I think the fluid in it cannot be brought to the 
mark with nearly the same degree of accuracy. These objec- 
tions, joined to the consideration that no object can be attained 
in this way, which was not accomplished, with at least equal 
accuracy, and probably no greater trouble, by weighing the 
spirit and water separately, determined us not to attempt any 
experiments with such an instrument. 
Thirdly, it is now to be explained why we undertook to 
determine the effect of heat and cold on the fluids, by means of 
the weighing-bottle. When, preparatory to our former expe- 
riments, that part of the subject came under consideration, the 
method of ascertaining the expansions and contractions, by 
means of instruments like thermometers, was one of the first 
3 K 2 
