294 ESSAYS anp OBSERVATIONS 
the quick-filver, till there is fuch a heat ap- 
plied, as will almoft bring the liquor to boil, 
and even then the folution goes on flowly 
and quietly: laftly, to diflolve one ounce of — 
quick-filver, it requires, at leaft, three ounces 
of oil of vitriol; and yet the quick-filver will 
not be entirely fufpended in this ponderous 
liquor. 
EvEN water, tho’ it diffolves all kinds of 
falts, yet it does not act upon all of them 
with the fame eafe; that is, the fame quan- 
tity of water cannot diffolve an equal quanti- 
ty of each falt, in the fame time, or with the 
fame degree of heat; for an ounce of cold 
water will foon diffolve half an ounce of 
 falt of tartar; but half an ounce of crude 
tartar cannot be diffolved in lefs than ten 
ounces of water; and that quantity of cold 
water will make no folution until it is brought 
to boil, and continues to boil for fome time, 
new water being added to fupply the watte. 
Even that compound falt, made of the fixt 
falt and chryftals of tartar, which, from its fo- 
lubility, with refpect to common tartar, gets 
the name of ¢artarus folubilis, requires little 
lefs than ten times its,weight of warm wa- 
ter to diffolve it fully. 
VII. Some 
