144 



June 12, 1856. 



The LORD WROTTESLEY, President, in the Chair. 



The following gentlemen were admitted into the Society : 

 Sir John Fox Burgoyne, Bart. 

 Philip Henry Gosse, Esq. 

 Archibald Smith, Esq. 



The following communications were read : 



I. " On the Construction of the Imperial Standard Pound, and 

 its copies of Platinum ; and on the comparison of the Impe- 

 rial Standard Pound with the Kilogramme des Archives." 

 By W. H. MILLER, M.A., F.R.S., Professor of Mineralogy 

 in the University of Cambridge. Part II. Received 

 June 7, 1856, 



(Abstract.) 

 The Quartz Weight 



The hardness of quartz, its capability of taking a high polish, the 

 absence of any hygroscopic properties, and its indestructibility at the 

 ordinary temperature of the atmosphere by any chemical agent ex- 

 cept hydrofluoric acid, are such valuable qualities in a substance 

 used for the construction of weights, that Professor Steinheil adopted 

 jt as the material for a copy of the kilogramme. The only objection 

 to the use of a weight made of quartz is, that on account of the 

 large amount of air displaced, the barometer and thermometer must 

 be observed with extreme care daring its comparison with a weight 

 made of any ordinary metal. The Committee commissioned Mr. 

 Barrow to construct a weight of quartz sufficiently near to 7000 grs. 

 to admit of readily deducing the pound from it. Its form is that of 

 a cube of about 2'2 inches, having its edges and angles rounded. 



