Manchester Memoirs, Vol. xlv. (1901), No. 15. 



XV. The Influence of Grinding upon the Solubility* of 

 the Lead in Lead Fritts. 



By T. E. Thorpe, C.B, LL.D., F.R.S., 



AND 



Charles Simmonds, B.Sc. 



Received May i^^', 1 901. Read May 2?>lh, 1901. 



A paper dealing with this subject was communicated 

 to the Manchester Literary and Philosophical Society on 

 October 30th last, by Messrs. Jackson and Rich, of the 

 Victoria Institute, Tunstall. 



The main purport of the paper was to show that, in 

 the case of lead fritts, " solubility in dilute acid is 

 "greatly influenced by the degree of fineness to which 

 " the particles have been ground." {Manchester Memoirs, 

 vol. 45, part I., No. 2, pp. 6-"/). Starting with the 

 assumption that solution is possible only from the 

 surface of the particles, the authors contend that, since the 

 extent of surface of any given weight of fritt is increased 

 by decreasing the size of the particles, the action of the 

 solvent is also increased. They adduce certain experi- 

 mental results which are considered to support this 

 contention. 



In connection with the matter under discussion it 

 should be pointed out that the Home Office has recently 

 suggested a criterion whereby the comparative harmless- 



* Throughout this paper the term " solubility " denotes the weight of lead, 

 calculated as monoxide, dissolved from a powdered fritt or glaze when the 

 fritt or glaze is shaken for an hour with looo times its weight of 0*25 per 

 cent, hydrochloric acid and allowed to settle for a further hour before being 

 filtered. 



Septet7iber loth, igor. 



