DRESSING OF ORES 



127 



while the lightest collect into the third or largest one c ; the result in each case being 

 modified as may be desirable, by increasing or lessening the flow of water from the 

 vertical pipes, d, e,f. 



712 



The length of the trough is six feet, greatest width 28 i inches, decreasing to 11 

 inches, depth 18f inches, diameter of vertical pipes' f inch and of main pipe 

 3 inches ; length of first receptacle 18 inches, second 

 24 inches, third 30 inches. The classified sand from first, 

 second, and third compartments is in each case passed 

 to suitably enriching machinery. The principle affecting 

 tho classification by the apparatus described is as 

 follows : 



In a horizontal current of decreasing velocity, the 

 larger equivalents introduced will be deposited first, 

 decreasing in size in an equal ratio with the decreasing 

 velocity, till with but a very slight flow even the finest 

 slimes are deposited. A stream rising vertically with 

 decreasing velocity, carries the smallest equivalents first 

 away and only the larger ones remain, while in propor- 

 tion to the decreasing velocity of the stream the fine 

 and finest particles will eventually be deposited. In 

 the construction of these classifiers, the following rules 

 should be adhered to : 



The width of the first division should be ^th of a 

 foot for each cubic foot of slime water introduced per 

 minute. The following divisions should increase in 

 geometrical progression, thus, 1, 2, 4, &c. The length 

 of the first division is usually taken at 6, the second, 

 third, and fourth in arithmetical proportion, thus, 6, 9, 12, &c. The inclination of 

 the sides of the box should be about 50. 



