on Spirituous Liquors* J23 
ing with refpedl to that standard, but not much fo within the 
above-mentioned interval ; whilft water kept from freezing to 
30% which may eaiiiy be done, will abfolutely contrafl: as it is 
heated for ten or more degrees, that is, to 40° or 42° of the 
thermometer, and will then begin to expand as its heat is 
augmented, at firft (lowly, and afterwards gradually more ra- 
pidly, fo as to obferve upon the whole a very increafing pro- 
greffion, Now, mixtures of thefe two fubftances will, as 
may be fuppofed, approach to the lefs or the greater of thofe 
progreffions, according as they are compounded of more fpirit 
or more water, whilft their total expanfion will be greater^ 
according as more fpirit enters into their competition ; but the 
exa6t quantity of the expanfion, as well as law of the pro- 
greffion, in all of them, can be determined only by trials* 
Thefe were, therefore, the two other principal objects to be 
afceriained by experiment. 
The firft ftep towards a right performance of the experi- 
ments was to procure the two fubftances with which they were 
to be made as pure as poffible. Diftilled water is in all cafes 
fo nearly alike, that no difficulty occurred with regard to it; 
but the fpecific gravity of pure fpirit, or alcohol, has been 
given fo very differently by the authors who have treated of it$ 
that a particular fet of experiments appeared neceffarv for de- 
termining to what degree of ftrength rectified {pints could 
conveniently be brought. The perfon engaged to make thefe 
experiments was Dr. Dollfuss, an ingenious Swifs gentle- 
man then in London, who had diftinguifhed himfelf by feve- 
ral publications on chemical fubjefts. Dr. Dollfuss, having 
been furniffied by Government with fpirit for the purpofe, 
re&ified it by repeated and (low diftillations till its fpecific 
gravity became ftationary in this manner of operating : he then 
U u 2 added 
