[ 5^o ] 
they appeal* to be impregnated with Coal, Smoak, 
and Soot, which renders them dill more foul and 
impure, makes them of a black, brown, or green 
Colour, and of a peculiar fulphureous Quality. On 
this account they are intirely unfit for making white 
Glafs: They make a very coarfe and firong kind of 
Soap; they are too foul, lharp, and corrofive for 
bleaching, and are as unfit for dyeing, at lead many 
Colours. • * 
It is perhaps for this Reafon, that the Workmen 
here, as they (hewed me themfelves, make all their 
white Glafs with Salt-pctre ,• which muft not only 
be more codly, but Neri, Merrett , and others, tell 
us it is not fo good, at lead for the better Sorts of 
Glafs, as a fharper lixivial Salt. What they ufefor 
dyeing I am not fo well apprifed of: It is faid, they 
ufe the volatile Alkali of Urine ; but the French 
Pot-afh, made of the Lees of Wine, is generally al- 
low'd to be the beft for that Purpofe. So likewife 
the Alicant Pot-afh is reckoned much the bed for 
bleaching, and making of Soap j as the Syrian and 
Egyptian is for making Glafs. 
Thcfe purer Kinds of Pot-afh are all made of 
Herbs, that grow only in the more Southern Cli- 
mates, whofe Salts are finer and whiter, and lefs 
acrid and corrofive than the Salts of Wood, or mod 
other Vegetables; and by the Way of extracting 
them by Calcination in a more open Fire, they are 
more free of Coal, Smoak and Soot, or any other 
heterogeneous Mixture. On this account they are 
much better for the Purpofes above-mention’d, than 
the coarfe and foul Kinds of Pot-alh that our People 
are fupplied with. 
All 
