new method of preparing Pot-ajh. 34-9 
This pot-afh is of a greyifh white appearance, deli- 
quefces a little in moift air; but if kept in a dry room, near 
the fire, acquires a powdery furface. It is hard, and of a 
fpongy texture when broken, with many fmall cryftals in 
its fubfiance. The colour of its internal parts is dulky and 
variegated. To the tafte it is acrid, faline, and fulphure- 
ous. It emits no fmell of volatile alkali, either in a folid 
form, diflolved, or when added to lime-water; neither 
does it communicate the fapphire colour to a folution of 
blue vitriol. Silver is quickly tinged black by it, a proof 
that it contains much phlogifton. Ten grains of this pot- 
alh required eleven drops of the weak fpirit of vitriol to 
faturate them. The like quantity of fait of tartar re- 
quired, of the fame acid, twenty-four drops: a ftrong 
effervefcence occurred in both mixtures ; from the for- 
mer a fulphureous vapour was exhaled. A tea fpoonful 
of the fyrupof violets, diluted with an ounce of water, was 
changed into a bright green colour by five grains of the 
fait of tartar; but ten grains of this pot-afh were necef- 
fary to produce the fame hue, in a fimilar mixture. Half 
an ounce of the pot-afh diflolved intirely in half a pint 
of hot water ; but when the liquor was cold, a large pur- 
ple fediment fubfided to the bottom : and it was found, 
that this fediment amounted to about two-thirds of the 
whole quantity of allies ufed. 
A a a z 
I have 
