1900.] 



on Pottery and Plumbism. 



405 



Table showing that from certain kinds of fritts and glazes, lead, oxide is 

 dissolved by 0'25 per cent. HCl to practically the same extent as from 

 "raw" lead. 



Lead oxide dissolved, 



expressed as percentage 



of total lead oxide present 



Lead silcate 0, 99-6 



„ 2 99-6 



Glaze S, made with lead silicate 99-2 



Glaze H, „ „ 99-tf 



„ . . - ("Litharge 100-0 



Vnnous forms of Red le ^ 100 . 



raw lead .. | white lead 100 -0 



Next the inquiry showed that there was no necessary relation 

 between the amount of lead oxide in a " fritt " and the extent to which 

 it would yield lead to solvents comparable as regards their action with 

 animal secretions. Some of the compounds richest in lead were, in 

 fact, among those least attacked by solvents. 



Tables showing that the amount of lead oxide dissolved from a fritt by 

 0*25 per cent. HCl bears no direct relation to the amount of lead 

 oxide in the fritt. 



I. — Solubility practically the same ; amounts of lead oxide in the 

 fritt very different. 



Maastricht fritt (preparation) 

 Fritt B 103a (preparation) .. 



Boch's fritt 



Fritt B 103 



,. B 2a (preparation) 



II. — Solubilities very different ; amounts of lead oxide in fritt 

 practically the same. 



Percentage 



] of Lead oxide in 



lritt. 



English fritt j 37-9 



Fritt M, 36-2 



Owen's fritt : 45'8 



Almstrom's fritt ; 44 - 1 



Solubility 



per cent, on 



fritt. 



28-0 

 1-4 



10-8 

 21 



