9G6 Transactions of the American Institute. 



Dry Ore Skparator. 

 Mr. P. M. Kandall exhibited a model of Chnbbs' Dry Ore Sepa- 

 rator and Concentrator. The machine is constructed so as to cause 

 puffs of air to pass through finely reduced ore for the purpose of sep- 

 arating it according to its specific gravity. The bellows is worked by 

 means of a lever underneath. The ore bed is made of cloth, so that 

 the air can pass through it ; the bed inclines in two directions, and 

 as the ores become separated the heavier ore, conducted by a guide 

 plate in one way, while the lighter passes in an opposite direction. 

 In separating the mineral from tlie gangue, or vein-stone, it is nec- 

 essary to finely reduce and size the ore ; for if the ore be not finely 

 reduced, the mineral will adhere to the gangue, and the ore be 

 imperfectly separated ; and if not sized, the larger grains of gangue 

 will mingle with the mineral. This machine has been used success- 

 fully in treating the ores of galena graphite, (principally Ceylon ores) 

 iron and gold bearing rock, containing sulphuret of iron, cobalt and 

 nickle. The size of the working machine is six feet long and twenty 

 inches wide, and it is capable of separating from one-half to one and 

 ' a half tons of ore per hour ; the finer ores requiring the longer time. 

 Mr. Chubbs commenced his experiments in dry ore separating in 

 1852, and nearly perfected his machine in 1853, and apjjlied for a 

 patent in 1854 ; but owing to a controversy between Mr. Chubbs and 

 Mr. Seymour, the patent was not granted till 1S5T, it being shown 

 in the end that Seymour used water and Chubbs air. It is well 

 known that there is a prejudice among miners against dry concentra- 

 tion, on the grounds that it is destructive to health and machinery ; 

 that a less amount of ore can be worked dry than wet ; that it is 

 more expensive ; that the ores coming crude from the mines are usu- 

 ally mixed with slate and clay, and are quite wet, requiring to be 

 dried ; that in the treatment of most gold-bearing rock it had not 

 generally been found advisable to reduce it all to a very fine powder 

 or slime, but to a size so as to pass through, say a forty-mesh serene, 

 than to concentrate the richer and heavier portions, and reduce theni 

 finer. In the treatment of gold he believed that full as much of the 

 fine metal would be lost by the wet process as by the dry. He also 

 stated that in the treatment of most silver ores, (sulphides of silver), 

 since the crystals are very fine and firmly attached to the vein-stones, 

 it has been found advisable to crush and grind the entire mass to the 

 finest powder or slime, so that concentration, either wet or dry, has 

 been shut out in the process. It has been said tliat experience shows 



