222 



REPORT — 1873. 



Eesult. — The silver is removed by the action of the acid ; and the gold 

 remains in a spongy state. 



5th process. — The sponge of gold retains the original form of the coil ; but 

 it is necessary to impart a certain degree of coherence to the metal by 

 annealing it at a dull red heat. 



It may be observed that a small quantity of silver is invariably retained by 

 the gold. It is necessary therefore to make check assays on pure gold or on 

 standards of known composition, upon which the accuracy of the result will 

 in a great measure depend. 



CtfJi process. — This, the concluding process, consists in weighing the gold 

 " cornet." The weights implied bear a decimal relation to the original 

 weight of the assay piece operated upon ; and therefore the amount of gold 

 present in the alloy is at once indicated without further calculation. 



Table showing the Relative Purity of Samples of Gold prepared by 



diiFerent Methods. 



Sample. 



A. 



B. 



C. 



D. 

 E. 

 F. 

 G. 



From a dilute solution of chloride of gold 

 by sulphurous acid gas 



From chloride of gold by oxalic acid . . . 



The trial-plate, prepared by same process 

 as Sample A 



Prepared by a 



Prepared hj ft 



Prepared by y 



Prepared by ^ 



1000-00 



999-98 



999-95 



999-93 

 999-80 

 999-70 

 999-60 



First Report of the Committee for the Selection and Nomenclature of 

 Dynamical and Electrical tlnits, the Committee consisting of Sir 

 W. Thomson, Professor G. C. Foster, Professor J. C. Maxwell, 

 Mr. G. J. Stoney, Professor Fleeming Jenkin, Dr. Siemens, Mr. 

 F. J. Bramwell, and Professor Everett (Reporter). 



We consider that the most urgent portion of the task intrusted to us is that 

 which concerns the selection and nomenclature of units of force and energy ; 

 and under this head we are prepared to offer a definite recommendation. 



A more extensive and difficult part of our duty is the selection and nomen- 

 clature of electrical and magnetic units. Under this head we are prepared with 

 a definite recommendation as regards selection, but with only an interim 

 recommendation as regards nomenclature. 



