4 Burton, Plumbism in Pottery Workers. 



Avithin 50*^ to ioo*^C. Leadless glazes of the kind under 

 discussion are unduly sensitive in this respect, and appear to 

 have a very limited range of temperatures within which 

 they can be depended on to come clear, bright and glossy.* 

 Again, leadless glazes do not flow very easily, but mani- 

 fest a great tendency to draw back from sharp edges or 

 surfaces, and in extreme cases they often " ruckle " all 

 over or draw up into beads. They frequently exhibit a 

 tendency to become " opaline," especially when the}- con- 

 tain a considerable proportion of lime or barium. These 

 defects, and man}- others which are of too technical a 

 nature to be diccussed here, have always stood in the way 

 of their general adoption. 



The common experience of potters for centuries has 

 proved that, of all glazes fired at comparatively low tem- 

 peratures, those containing lead compounds are by far the 

 simplest in use, and the most reliable in practice. Many 

 instances might be given, some of them dating from remote 

 centuries, to prove that leadless glazes have been often 

 abandoned for those containing lead ; so that when, in the 

 last century, England became a great pottery-producing 

 country, the use of glazes containing lead was already firmly 

 established in Europe. The use of lead glazes is therefore 

 not a question of the ignorance or obstinacy of English 

 manufacturers, as we are sometimes given to understand; 

 nor is it because we lack technical knowledge possessed 

 by our German or French rivals. English domestic 

 pottery is admittedly the best in the world. The varieties of 

 earthenware and china made in this country were invented 

 and have been perfected here, and differ fundamentally 

 from the indigenous products of other countries. In fact, in 

 discovering English earthenware and English china, the 

 English potter produced species of pottery more easy to 

 • Sample? of tiles and pottery were shewn to illustrate this point. 



