222 ESSAYS anp OBSERVATIONS 
two drams of falt of tartar, nearly as fix 
_ to five. : 
THESE experiments are therefore agree- 
able to that part of the fecond propofition 
which relates to the cauftic alkali. 
Upon iarther-examining what changes 
the alkali had undergone, I found that the 
ley gaveonly an exceeding faint milky hue 
to lime-water; becaufe the cauftic alkali 
wants that air by which falt of tartar pre- 
cipitates the lime. Whena few ounces of 
it were expofed in an open {hallow veffel 
for four and twenty hours, it imbibed a 
{mall quantity of air, and made a flight 
effervefcence with acids. After a fort- 
night’s expofure in the fame manner, it 
became entirely mild, effervefced as vio 
lently with acids, and had the fame effect 
upon lime-water, as a folution of an ordi- 
nary alkali. It likeways agrees with lime- 
water in this refpect, that it may be kept 
in clofe veffels, or even in bottles which 
are but flightly covered, for a confidera- 
ble time, without abforbing a fenfible 
quantity of air. 
In 
