1870.] On the Method of Assaying Silver. 385 



with distilled water : for each, bottle there is placed on the floor of 

 the trough a small porcelain saucer holding a little Wedge-wood 

 crucible or cup, each numbered to correspond to the bottles. A 

 laboratory workman then removes the stoppers from the bottles 

 and hands them one by one to an assistant at the trough, who 

 placing his forefinger over the mouth of each bottle inverts it over 

 its corresponding cup, and does not remove his finger till the neck 

 of the bottle has passed down through the water and well into the 

 cup : then the finger being taken away the bulk of the chloride 

 falls by its own weight to the bottom of the cup. 



The bottle is held in the position by two rings one (the larger) 

 above the other, which are fixed to the sides of the trough : this 

 arrangement retains each bottle in situ, at the proper slant, and 

 admits of the operator gently revolving or slightly raising the 

 bottle with his left hand, while with the right he patiently taps 

 the bottom and sides till the whole of the chloride has been dex- 

 terously got out, the finger is then again placed over the mouth 

 and the bottle raised up through the rings and handed (mouth 

 upwards) to the assayer, or to the supervising assistant standing by, 

 who carefully examines it to see that every particle of chloride has 

 been dropped into the cup. When this part of the manipulation 

 has been neatly done, none of the chloride falls over into the saucer 

 which is placed as a precautionary measure under each cup. 



When the chloride falls into the cup, it is in an uneven lumpy 

 state and not in a favourable condition for being uniformly dried, 

 it has therefore next to be broken up. For this purpose the cups 

 (containing the chlorides, and water to the brim) on removal from 

 the trough are taken in batches on a tray to an assistant seated at a 

 steady table, who first carefully decants off about half the water, and 

 then with a finely polished glass rod (four inches long and one-third 

 inch thick) gently stirs and beats the lumpy precipitate, while 

 revolving the cup on the table ; this causes it to lie evenly and 

 loosely at the bottom of the cup as a purplish grey powder, not too 

 fine. 



He next washes the rod over the cup with distilled water from a 

 drop bottle, lest any of the chloride may be adhering to it, and sprin- 

 kles a drop or two from it on to the surface of the water in each 



