1900.] 



on Pottery and Plumbism. 



409 



consisted of lead, whereas the English fritts were for the most part 

 very easily decomposed by the same treatment, and gave up the 

 greater part of their lead to solution. 



This led to the surmise that the Continental fritts consisted, for 

 the most part, of comparatively stable chemical compounds, the 

 minute quantity of lead dissolved being due to some lead compound 

 — oxide or silicate — in a state of incomplete or unstable chemical 

 union. Experiment showed that this surmise was correct. By treating 

 a fritt, compounded so as to be within the limiting ratio, with acid, by 

 far the greater proportion of the soluble or incompletely fixed lead 

 may be removed, and an almost absolutely insoluble lead double 

 silicate is left. 



Preparations from Fritts. 



The powdered fritt shaken for six hours with a solution of • 25 

 per cent, hydrochloric acid ; insoluble residue (a) tested for solubility 

 of lead. 



These results have so far strengthened the hands of the Home 

 Secretary that he has felt justified in now requiring the potters to 

 abandon the use of " raw " lead, and he has given them a definite time 

 in which to make the change to " fritted " lead. But he has gone 

 further than this. 



He has also indicated to them that, after a further interval, a 

 standard of safety must be definitely fixed by special rules, and that 

 in order to allow them ample time in which to provide themselves with 

 glazes answering to such a standard as is prescribed in a circular letter 

 which he has caused to be sent to the whole trade, the Secretary of 

 State proposes to allow an interval of two years before bringing it 

 compulsorily into force. 



I am gratified to be able to tell you that a number of manufacturers 

 and professional fritt makers, acting in conformity with the sug- 

 gestions which have been put forward, and in response to the invita- 



Vol. XVI. (No. 94.) 2 e 



