562 On the Refinage of under standard Silver. [June, 



This at once limited each batch to some 301ns weight of metal, or about 

 1 000 tolas, and where we had to deal with tons and lacs its adoption 

 seemed hopeless. It occurred to me however, to make trial of the ordi- 

 nary cast-iron melting pots of the mint, and I soon found to my great 

 satisfaction that by a little management these could be used with com- 

 plete success. The object in view was accordingly gained to the fullest 

 extent required, and in September, 1846, this system of refinage was 

 applied in one working-day (the 4th Sept.) to the very large quantity of 

 188,264 tola wt. of coarse silver — Troy pounds 5,883, value Co.'s Rs. 

 172,860 10 2, or ^£17,286 Is. 3d. which was refined and returned 

 to the mint in bright malleable ingots, and registered for assay in 

 less than six hours from the commencement of the operation. I believe I 

 am justified in asserting that in point of rapidity, economy and quantity, 

 this day's refinage has never been equalled in any refining establishment 

 in any part of the world. I now proceed to the detailed description of 

 the process — its expenses and total results. 



The cast-iron silver melting pots used in the mint, are of cylindrical 

 shape, with round bottoms, 17 inches external height, 11^ inches, inter- 

 nal diameter, 1^ inch thickness of metal. The quantity of silver usually 

 melted in each pot is 10,000 tola wt. or 312^ Troy pounds. If the 

 silver to be refined is in the state of coin the operation may be com- 

 menced at once. If in bars or other solid masses it must be granulated. 

 For this purpose about 8000 tola wt. are melted and poured from the 

 pot placed on a suitable frame over a tank of water, beneath the surface 

 of which two or three brooms are kept in constant motion. This 

 reduces the silver to granules like small shot. 



6000 tola wt. of under standard coins or granules are placed in 

 each iron pot, and heated to low redness in the ordinary melting fur- 

 nace, of which there are 16 in the mint. When at a low red heat the 

 mass of silver is hollowed out with an iron rod with flattened end, so 

 as to make a funnel-shaped depression of the metal in the centre. 

 About 2 pounds weight of saltpetre are thrown into this hollow. The 

 saltpetre rapidly melting percolates through the granules or coins, and, 

 as it filters through parts with its oxygen to the base metals. After a 

 few minutes the fireman with the same rod stirs up the silver from 

 the bottom of the pot and works it in every direction, again cupping 

 the centre as before. The heat is slightly urged and the saltpetreing is 



