210 THE CANADIAN NATURALIST. [June 



intended effect can be produced. Although the auriferous ores 

 of Nova Scotia may be deemed pyritous, yet they are compara- 

 tively free when contrasted with the ores of Colorado. These are 

 highly pyritous, and calcination or desulphurization is now being 

 carried on to a great extent. In the process known as Keith's, 

 the ores are first crushed to a fine powder, and then submitted to 

 the action of fire by being drawn through a flue, and are deposited 

 in chambers at the other end. By actual trial, one cord (128 

 cubic feet) of ore, weighing 14,700 lbs. weighed only 8871 lbs. 

 after being submitted to this process; having lost 5829 lbs., which 

 had passed away in vapor. That the yield of gold was increased 

 may be learned from the fact that a cord of ore treated by the old 

 process yielded at the rate of $100 per cord, whereas after being 

 desulphurized the yield was $864, — nearly a ninefold increase.* 



The quartz is brought from the kilns to the mill, and is there 

 broken up into small pieces, either by hand or by means of a 

 cracker. This machine consists of a heavy-recessed cast-iron bed- 

 plate ; two sides of the recess (which is about twelve inches deep) 

 are vertical, and the other two are inclined towards each other. 

 On the sloping faces are secured corrugated plates of cast iron. In 

 the recess, working on a pin in its lower end, is a heavy iron block 

 having corrugated plates on two faces. This block works back- 

 wards and forwards in the recess, and the quartz, being fed between 

 the plates, is gradually crushed up, and falls out at the bottom. 

 By the use of this machine a large quantity of quartz can be 

 crushed in a day, better than it can be done by hand, and at a 

 cheaper rate. 



After being cracked, the quartz is submitted to the operation of 

 crushing, two modes of which are in operation in the Province, 

 viz., by stamps, and by Chilian mills. The stamps are of two 

 kinds, square and revolving. In either case a battery consists of 

 a box, which may be made of cast or wrought iron, or of 

 wood faced with boiler-plate ; the bottoms of both kinds being 

 made of cast iron, and protected by small plates called anvil-blocks. 

 In the stamper-box are placed either four or six stamps ; a stamp 



* The process here referred to as Keith's appears to be an imperfect 

 form of that employed in the novel and ingenious methods of Messrs. 

 Whelpley and Storer, of Boston, which seem destined to revolutiunize the 

 art of metallurgy. See, for a brief notice of them, Silliman's Journal 

 [2 J, xxxvii, 401. — Eds. 



