MancJicstcr Memoirs, Vol. xlv. (1900), No. !^. 7 



influenced by the degree of fineness to which the particles 

 have been ground, we next enquired if there exists any 

 recognised standard of fineness for the grinding of glazes. 

 It is a matter of common knowledge that the fineness of 

 a glaze is intentionally varied according to the purpose 

 for which the glaze is required ; but even in the case 

 where it is desired to obtain the same degree of fineness, 

 when we considered the means adopted by the mill-man 

 to test the fineness, it seemed to us that great variations 

 must be expected. We therefore collected seven repre- 

 sentative finished glazes, and subjected them to elutriation, 

 by which means the fineness of each was determined. 



The results obtained are set out in the following table : 



Highest, 2842) Meani 866. 

 Lowest, io66j 



These figures for surface give the relative areas of 

 equal masses of the different glazes. 



It is therefore clear that great differences exist in the 

 degrees of fineness to which glazes are reduced by various 

 manufacturers. 



* In computing the relative surface of glaze-particles, it has been assumed 

 that the surface-area of unit mass varies inversely as the mean diameter of 

 the particles {cf. Pottery Gazette^ Oct., 1900.). 



