[ 6-8 o ] 
the Point of Temperate, which he determines by 
placing his Inftrument in a fubterranean Cavern, 
which is neither affe&ed by Frofl: nor Sunfhine, but 
is obferved to keep an equable Temperature all the 
Year round; fuch as deep Cellars and Wine-Vaults 
commonly do. In boiling Water he finds that his 
Thermometer rifes to his Soth Divifion,* or 80 De* 
grces, which are formed by dividing the Spirit when 
condenfcd to the freezing Point, into 1000 equal 
Parts ; fo that, with the Heat which makes Water 
boil, the Spirit is expanded only 7™, more than 
with the Cold which freezes Water. 
Thefe Spirit-Thermometers are of CJfe in Experi- 
ments where fomewhat greater Cold than the freez- 
ing of Water is required ; but they can never be of 
Ufe in any Degrees of Heat beyond the boiling of 
the Spirit itfelf s becaufe it then becomes volatile; 
or rifes up in Steam, and not only expands no more, 
but likewife the Quantity is diminifhed by the Parti- 
cles which fly up from the Surface of the Liquor, 
and are ftifpeilded in the Top of the Tube. 
Many have filled their Thermometers with various 
Sorts of Oils*f*: Thefe indeed will meafure many 
Degrees above the boiling of Water, till they boil 
themfelves ; and then they have the fame Defed as the 
Spirit 
* But, with Submiffion to fo great a Man, I cannot apprehend 
that his Thermometers, when the Spirits are raifed up to 80 do 1 
mark any greater Degree of Heat than their own fpecific boiling ’ 
Heat, which, if they are Alcohol , or the moft re&ified Spirits, an- 
fwer to 174. of Fahrenheit's Scale ; if of the Strength of common 
Brandy to 190. f See Dr. Martin's ElTays Med, & Philof* 
p. 22$. 
