352 ESSAYS ann OBSERVATIONS 
or than that which had been fo long expofed 
to the air (13). 
d From the aluminous tafte of the falt 
(14. 27). 
«. FRom its falt fwelling and rifing into a 
blifter on the hot iron (18). 
¢. From this falt lofing its aluminous tafte 
when calcined a fufficient time (17), which 
alfo happens to alum, when treated ina like 
manner, 
THE nitrum murale, it is true, alfo {wells 
and rifes in blifters on the hot iron; likeways 
borax, and the purging falt of Scarborough 
water: but the trum murale differs from 
this falt in tafte, and, when calcined, falls 
down into a loofe powder, like lime; which 
this falt did not do, tho’ calcined ‘for a confi- 
derable time, in a ftrong fire. 
Borax likeways differs in tafte from this falt, 
and vitrifies in a moderate heat, in a few mi- 
nutes; which this falt did not, after being — 
calcined in a {trong heat for a confiderable 
time. ‘This falt has not the bitter penetra- 
ting tafte of the purging sons falt, 
neither its purging quality. 
I don’t however pretend that all thofe 
marks amount to a demontftrative proof that 
there 
