404 Professor T. E. Thorpe [May 4, 



Compounds of lead have been employed by the potter in one form 

 or other from time immemorial : they are such valuable adjuncts that it 

 is not to be supposed that lie will lightly abandon their use. Indeed 

 absolute prohibition of lead compounds in the pottery industry is 

 hardly practicable, for there are certain branches of the manufacture 

 in which it appears to be impossible to dispense with them. Moreover, 

 no such prohibition is in force among Continental manufacturers who 

 compete with our own producers, not only at home, but in almost every 

 foreign market. 



Lead poisoning among pottery manufacturers is not unknown on 

 the Continent ; but it is by no means so common as with us. This 

 fact at once seems to show that it is rather the manner in which the 

 lead compounds are used than their actual use which occasions the 

 mischief. When we inquire what it is in Continental procedure that 

 occasions this marked difference, we are at once struck with the fact 

 that what is known as " raw " lead — that is, the white lead or red 

 lead - is comparatively seldom employed on the Continent in the 

 mixture in the glaze-tub. In the greater number of well-organised 

 Continental factories the lead employed is mainly " fritted," that is, it 

 is used in the form of a double silicate. The fact that " fritted " lead 

 is, as a rule, more innocuous than " raw " lead is not unknown to the 

 pottery world, and in an inquiry which was instituted by the Home 

 Office in 1893, manufacturers whose names deservedly carry authority 

 in the pottery districts strongly urged the substitution of " fritted " 

 lead for " raw " lead in all glazes. Unfortunately, however, this 

 recommendation was not enforced. This may have been due, partly 

 at least, to the circumstance that cases of plumbism occurred from time 

 to time in works where " fritted " lead was exclusively used. The 

 fact is, there is " fritted " lead and " fritted " lead. And now I come 

 to the first of the two main points of my lecture. 



You are aware that the toxic action of lead depends upon its 

 solubility in the system, especially by the aid of the gastric juice. I 

 wish, therefore, to explain to you, as shortly as possible, the results of 

 a recent inquiry into the conditions which determine the ease with 

 which lead may be dissolved out from a " fritt " by dilute acids, such 

 as are present in gastric juice. The conditions which determine its 

 solubility may be said to determine its toxic action. 



In the course of this inquiry I have, with the assistance of Messrs. 

 Simmonds, More, and Fox, assistants in the Government laboratory, 

 analysed a considerable number of Continental and English "fritts," 

 and have determined the relative ease with which they may be attacked 

 by a dilute acid comparable in strength with that existing in normal 

 gastric juice. In the first place, I found that, speaking generally, such 

 English "fritts" as I could obtain yielded a far larger amount of 

 lead to solvents than those made in Holland, Belgium, Germany, or 

 Sweden. Indeed, some English specimens of "fritted" lead were 

 found to be hardly less soluble than "raw " lead. This may be seen 

 from the following : — 



