THE DISPOSAL AND UTILIZATION OF RESIDUALS. 13! 



cent. pure. A properly made sample will be fairly white, 

 and will dry readily on exposure to air. If it remains 

 sodden and damp, and is of a bad colour, there is some 

 mistake in the working. I have heard a great deal about 

 trouble in this connection, and of " blue," " dirty," or 

 damp salt, but have had very little trouble in practice. 

 By careful attention to a few simple rules, these troubles 

 can be avoided. 



A small works using 300 tons of coal per annum may 

 expect to make about 4,500 gallons of 6 or 7 liquor, 

 from which can be obtained about 2^ tons of sulphate. 

 Taking the cost of acid at ^3 per ton, and the net selling 

 price of sulphate at ;n, we have a gross income of 

 ^27, i os., less ^7, i os. for acid, which leaves 20 for 

 labour, incidentals and profit. So that even under these 

 circumstances an outlay of ^80 to .100 for apparatus 

 would be a good investment. The necessary apparatus 

 comprises a boiler capable of containing 800 gallons of 

 liquor, saturator, acid tank, mother liquor or draining tank, 

 tipping board, lead-lined store, cooling coil and oxide 

 purifier. The boiler is usually a second-hand one, picked 

 up at a low price, mounted over a furnace with narrow 

 bars and plenty of air space, to admit of using ashes or 

 breeze as fuel, and the condenser may be made up out of 

 second-hand 3-inch or 4-inch pipe, while a heap of oxide 

 in a corner will serve as a purifier. I have also found that 

 where an excess of boiler capacity is available, excellent 

 results can be obtained on the small scale by the use of 

 wet steam, instead of direct firing. An inverted V, formed 

 by old purifier grids built up over the mouth of the pipe, 

 serves as a distributor. The saturator and other lead work 

 should be obtained from one of the firms that specialize in 

 this line, as there is no economy in trying to make this up 



