242 THE CANADIAN NATURALIST. [Aug. 



per hour. The cost of feeding and attending the mill, and removing 

 the product, together with expenses of engine and fuel, would prob- 

 ably amount to $6.50 per day, or 8J cents per ton. The cost of 

 Whelpley and Storer's machine is somewhat more than that of 

 Blake's, and while nine horse-power only is required for the lat- 

 ter, fifteen is said to be necessary for the former. With these 

 data it may therefore be safe to estimate that the preliminary crush- 

 ing of the ore would cost 10 cts. per ton. The crushing by means 

 of ordinary rollers is here left out of consideration, as the ore must 

 be very much reduced in size (to two inches in diameter and less) 

 before it is possible to treat it by means of rollers. 



In reducing the ore to a finer powder than is possible by means 

 of any crusher, the choice lies between millstones, stamps, and 

 Whelpley and Storer's pulveriser. The operation of pulverising by 

 means of the first named is too expensive; and wet stamps, although 

 they do it cheaper, have this disadvantage that the drying of the 

 fine powder and the subsequent crushing of such parts of it as 

 might cake together would increase the cost materially. By far 

 the best pulveriser is undoubtedly that of Whelpley and Storer, 

 which with twelve horse-power reduces to a state of fine dust 

 from 1500 to 2000 lbs. of ordinary quartz or other stone per hour. 

 Assuming that this machine were driven by the same engine 

 which works the crusher, the cost of pulverising could not exceed 

 20 cents per ton. 



The pulverised ore, after having been mixed with the salt and 

 iron oxide, is next calcined ; and it would seem quite practicable to 

 effect this calcination in a semi-re verberatory furnace, the hearth 

 of which would consist of cast-iron plates heated by the . flame 

 from a furnace passing through flues beneath. The smoke, etc., 

 from the fire would be kept altogether, distinct from the gases 

 evolved by the ore and other ingredients during the calcination. 

 Since diligent stirring is rather injurious than otherwise, it fol- 

 lows that no great amount of labor is necessary ; and since the 

 temperature is to be kept as low as possible, it is also evident that 

 the expenditure of fuel will be inconsiderable. It is therefore 

 probably a reasonable estimate that $1 per ton would cover the 

 expense of calcination. 



The gases evolved during this operation are sulphurous acid 

 and chlorine in very nearly the proportions of their equivalents. 

 Partly to create a draft though the furnace and partly in order to 

 utilise these gases, it would be well to put into connection with 



