METALS AND THEIR ORES. 13 



Australia, 925.; the Chaiidiere region of Canada 885 to 900; while from 

 Nova Scotia the gold is very nearly pure. 



The method of extraction first employed is the ordinary stamp process, 

 ten small stamps rather lighter than usual, with copper and blanket 

 amalgamation. It is thought by those much experienced in quartz mill- 

 ing to have been carried on in a crude manner, yet the amount saved 

 has been a fair percentage of the assay yield. There were two of these 

 mills, one on each side of the river at Lisbon village. 



With the advent of the Electro-Gold company the Thunder-bolt crusher 

 replaced the stamps. The rock was heated, or partially roasted. It was 

 then crushed dry, and the powder placed in cylinders with water and 

 quicksilver, thirty pounds to a ton of ore. This cylinder revolves four 

 hours, and the sands flow into a dolly tub, afterwards passing over blan- 

 kets. The sulphurets are caught mostly in the tub, and saved for fur- 

 ther treatment. The blankets catch the fine gold, and are changed every 

 four hours. This mill could treat five tons of rock in ten hours. It was 

 the most successful of the various methods tried in New Hampshire, It 

 has since been used more extensively in Virginia. Being of little use for 

 the extraction of gold from sulphurets, Dr. Rae has added a desulphuriz- 

 ing furnace to his works, enabling him to treat ores otherwise intracta- 

 ble. We present herewith the original specifications of the patent de- 

 scribing this process. 



123,932. United Slates Patent Office. Julio H. Rae, of Syracuse, New 

 Tork. Improvement in 'Voltaic Amalgamators for Gold and Silver. 



Specification forming part of Letters Patent No. 123,932, dated February 20, 1872. 



To all whotn it may cojtcerti : 



Be it known that I, Julio H. Rae, of the city of Syracuse, in the county of Onon- 

 daga and state of New York, have invented a new and useful improvement in voltaic 

 amalgamators for ore ; and I do hereby declare the following to be a full, clear, and 

 exact description thereof, which will enable those skilled in the art to make and use 

 the same, reference being had to the accompanying drawing forming part of this 

 specification, in which drawing, — 



Fig. I represents a longitudinal vertical section of my invention. Fig. 2 is a plan 

 or top view of the same. Fig. 3 is a detached longitudinal central section of the 

 voltaic cylinder, which forms one of the principal parts of my amalgamator, in a 

 larger scale than the previous figure, the line x x; Fig. 4, indicating the plane of 



