&n Assaying Silver. 



[Apttit, 



+ 2 



s 







S 



+ 4 



s 



s 



— 2 



+ 1 



+ 1 





s 





- — , 







— 5 









— 2 





, , , „ , 



s 



. ■ j 





— 5 



— 7 



— 5 







- 2 









— 1 



— 2 







— 5 



— .5 



Front, 



8. By this it is seen that although each specimen of the 

 silver experimented on, was of the same fineness, yet the 

 assay did not uniformly give that indication, but exhibited 

 one of the musters to be finer than its true quality by four 

 tenths of a penny-weight, and others to vary from one to 

 seven-tenths of a penny- weight in coarseness, making there* 

 by the silver to be worse than it really was. This is attri* 

 butable, as I before observed, to the difficulty of causing 

 the fire to act precisely at the same temperature on each 

 individual muster: if the temperature was perfectly equal 

 throughout the muffle, there is reason to believe that the 

 Variations in the out-turn would be very small, but as perfect 

 equality of temperature is hot attainable in practice, perfect 

 Results are not to be expected. The absorption allowance is 

 equal to T % part of the original quantity or assay pound, 

 And as this pound is ail arbitrary small weight of not more 

 than from 15 to 20 troy grains, it is clear that a very small 

 practical error will materially affect uniformity of result. 



9. To the foregoing diagram I shall add two others, 

 exhibiting the results of experiments made by a regularly 

 educated assayer, for the purpose of determining the allow* 

 ance that ought to be fixed for the absorption of the cupel ; 

 they were made therefore with such care and precaution a? 



