Oft the fpecific Gravities, &c. of Saline Sttbfances. t$; 
we may confider the dilatation of Jpirit of nitre as equal to thofe 
of the quantities of water and acid it contains minus the condenfa - 
tion they acquire from their mutual attraction , and this rule holds 
as to all other heterogeneous compounds . 
To find the qualities of acid and water in fpirit of nitre, 
whofe fpecific gravity was found in degrees of temperature dif- 
ferent from thole for which the table was conffructed, viz. 54. 
55, or 56^ of FAHRENHEIT, the furefi: method is to find how 
much that fpirit of nitre is expanded or condenfed by a greater or 
lefler degree of heat, and then, by the rule of proportion, find 
what its denlity would be at 55 0 ; but if this cannot be dene, 
we fliall approach pretty near the truth, if we allow for 
every 15 0 of heat above or below 55 0 of Fahrenheit, when 
the fpecific gravity of fpirit is between 1,400 and 1,500; and 
-t-c'W when the fpecific gravity is between 1,400 and 1,300. 
As to oil and fpirit of vitriol I found the dilatations 
exceeding irregular, probably by reafon of a white foreign 
matter, which is more or lefs fufpended or diflolved in it, 
according to its greater or lefler dilution. This matter I would 
not feparate, as I intended trying the denfity of this fubftance 
in the ftate in which it is commonly ufed. In general I found, 
that 1 5 0 of heat caufe a difference of about in its fpecific 
gravity when it exceeds 1,800 ; and of when its fpecific 
gravity is between 1 , 400 and 1 ,300, its dilatation is greater than 
that of water, and fo much greater as it is ftronger. 
The dilatations of fpirit of fait are very nearly proportional 
to the degrees of heat, as appears by the following table* 
