f 22 ; 



day under It. The colour of the common pot- 

 tery ware is red, as the velTels are made of the 

 fame clay with common bricks. Thefe vefTels 

 are fo porous, that they are penetrated by all 

 faltSj acid or alkaline, and are unfit for retaining 

 any faline fubflance. They are improper, though 

 too often ufedj for preferving four fruits of 

 pickles. The glazing of fuch veiTels is corroded 

 by the vinegar; for, upon evaporating the liquor, 

 a quantity of the fait of lead will be found at the 

 bottom. A fure way of judging, whether the vi- 

 negar, or other acids, have dilTolved pailLof the 

 o-lazing, is, by their becoming vapid, or lofing 

 their lliarpnefs, and acquiring a fwcetilli taile by 

 Handing in them for fome time : in which cafe 

 the contents are to be thrown away as perni- 

 cious. ^^ 



The fubflance of the pottery ware commonly 

 called D.lft, the bed being made at Delft in 

 Holland, is a whitilh clay when baked, and foft, 

 as not having endured a great heat in baking. 

 1 he <j]azing is a compofition of calcined \tz<\y 

 calcined tin, fand, fome coarfe alkaline fait, and 

 fandiver \ which being run into a white glafs, th.« 

 while colour being owing to the tin, is afterwards 



ground 



