GOLD MmmG m coloeado. 573 



If a very clean product is desired the width of the washing surface may be 

 increased to 4 feet, making a total width of 5 feet ; or, maintaining a total 

 width of 4 feet, the distributing surface of the slimes may be reduced to a 

 width of 8 or 9 inches. The inclination of the table must be adapted to the 

 character of the material to be treated ; it should be about six degrees for 

 sands and three degrees for fine slimes. The supply of stuff to be treated should 

 not exceed j^^ of one cubic foot, containing 15 pounds of sands per foot; or x'a of 

 one cubic foot, containing 6 pounds of slimes per foot. According to this a 

 double table will treat in 24 hours 4.640 tons of sands, or 0,864 tons of slimes. 

 The amount of clear water required is about the same quantity per foot of distrib- 

 uting breadth as that which brings the ore upon the table ; so that if the 

 breadth of the ore-distributing surface is one foot, and that of the water-dis- 

 tributing surface is three feet, the quantity required for one table will be for sands 

 1^0 of one cubic foot per minute; and for slimes, ^^ of one cubic foot per minute. 

 The quantity of clear water must, further, be increased as the inclination of the 

 table is decreased. The outer edge of the table, that is the side opposite that on 

 which the ore enters, should have a little more water than the rest of the sur- 

 face, in order to carry oflf the heavier material that reaches that side. The 

 number of strokes per minute is, for sands, 70 to 80; for slimes, 90 to 100. 

 The length of each stroke depends upon the tension of the spring, d, by which 

 the table is pressed against the block, e. The spring has a length of 11 feet, 

 a breadth of 3 inches, and a thickness of 2 to 2 J inches. If the spring has a 

 tension of 180 or 200 pounds, the length of stroke should be for sands 2J 

 inches, and for slimes J to f of an inch. 



Under too strong tension of the spring the table makes its return move- 

 ment too speedily for the desired action of the particles ; the result is that 

 they move in the reverse direction. The operation of the table demands great 

 uniformity in treatment, especially as regards the number of blows and the 

 quantity of water and of material. When the stream carrying the material 

 upon the table contains less sand or slime per cubic foot than the maximum 

 above given, the tension of the spring should be relieved and the inclination of 

 the table diminished. Under ordinary conditions the average performance of 

 a double table is from two to four tons in twenty-four hours, with a consump- 

 tion of water of 1,000 or 1,500 cubic feet. One table requires ^ horse-power. 



