Manchester Memoirs, Vol. xlv. (1900), No. %. 



II. The Solubility of certain Lead Glasses or Fritts 

 used in the Preparation of Pottery Glazes. 



By William Jackson, A.R.C.S., 



AND 



Edmund Milton Rich, B.Sc. 



\Commiiiiicated by William Burton, F.C.S?[ 



Received and read October ^oth, igoo. 



By the term "Lead Fritt" is usually meant the glassy 



compound produced by fusing together a mixture of 



various silicates, silica and bases, of which last lead oxide 



is one. The following recipe is typical : — 



Red lead 227 parts by weight. 



Whiting 100 „ ,, 



China clay 65 „ „ 



Soda ash 53 



Flint 270 „ „ 



This may be expressed in chemical language thus : — 



04 PbO 1 



0-4 CaO \q)\ AlaOs 2 SiOa 



0-2 (NaK)oOj 



the coefficients referring to strict molecular weights. 



In manufacturing a fritt, the constituents are carefully 

 weighed, thoroughly mixed, and then fused completely in 

 a reverberatory furnace. The glassy substance thus pro- 

 duced is mixed with the other constituents of the glaze, 

 and ground with water on a mill. When it is reduced to 

 a smooth cream it is ready for use. 



During the past few years, as is well known, the 

 question of the solubility of such lead glazes in dilute acid, 

 of a strength approximating to that of the gastric juice, 



March nth, igoi. 



