82 Zinc Desih'crization. 



Utah. They are earthy carbonates and sulphates, with some 

 galena, such as are found in Little Cottonwood nnd Bingham 

 Canons. From the former place, they contain from 10 to 40 

 per cent, of lead, from 70 to 150 oz. of silver, 1 to 3 oz. of 

 antimony, and a trace of arsenic and zinc. From Bingham 

 Canon they contain 30 to 50 per cent, of lead, and 10 to 20 oz. 

 of silver. The copper in these ores is sometimes as high as 6 

 per cent. They are transported on an average 2,000 miles, 

 some of them being brought from New Mexico. Some argenti- 

 ferous blende from Colorado contains 450 oz. of silver, 10 per 

 cent, of lead, and 20 per cent, of zinc. When these ores have 

 been dressed, they are made into bricks for treatment in the 

 shaft-furnace. The Utah ores are made the base of the treat- 

 ment. The works also treat argentiferous lead from all parts 

 of the country. The ore arriving at the works is sampled and 

 assayed. When it is purchased at the mine, it is sampled by 

 the agent of the company, and assayed at the works. When 

 tlie assay of the agent's sample does not agree with that of 

 the mine-owners, they send a samjale. 



At the Wyandotte works, the sample is taken very simply. 

 The ore, crushed fine,* is spread evenly over an iron plate, and 

 the sampler. Fig. l,f which is simply two iron bars bent at right 

 angles and riveted together, is put down on it, separating the ore 

 into four parts ; opposite parts are taken, a new pile made and 

 divided in the same way, and so on until the sample is complete. 

 The argentiferous lead is assayed on a sample taken from the 

 top and bottom of both ends of the pig, and the mean of the 

 two is accepted as the value of the whole. Each lot of ore and 

 lead is kept separate as far as possible. They are not, however, 

 treated separately, as this would involve too much trouble and 

 expense. The separation is only made so as to treat material 

 of about the same value together, or to add it, in the treatment, 

 as different parts of the process require it. The owners are 

 either paid for it at prices for the gold, silver and lead, which 

 are fixed by the works or regulated by the marketeer the metals 

 when separated are delivered to the owner, a certain sum 

 being deducted for expenses, loss and profit. 



* Engineering, London, Eng., Vol. 22, p. 495. t Engineering, Vol. 22 p. 200. 



t The figures illustrating this paper are numbered consecutively on Plates III to XIII, 



