50 ANNUAL OF SCIENTIFIC DISCOVERY. 



which is, of course, greatest at the ]ioint of the intersection of the 

 ra3S, which is the centre of the tower' 



If the oi*e to be worked be a sulpiiide of copper or iron, for ex- 

 ample, coutaininj^ sulphur suHieient for its own comi)lete combus- 

 tion, the supply of pulverized fuel is now cut oil', and the ])ulver- 

 ized ore fed into the furnace by tlie second fan-blower. Falling 

 into the focus of radiation, with a sullicient supply of oxygen from 

 the fan-blower, the oxidation of each element of the ore is almost 

 instantaneous. 



Most of the ore falls at a bright red or white heat into the water 

 of the tank. 



Many ores furnish their own fuel in the sulphur they contain. 



When ores containing but little sulphur are to be burned, the 

 supj)ly of i)ulverized fuel nuist be constant. 



in working ores containing copper, this metal is founil in solu- 

 tion with some iron, as a soluble salt, the nature of which will be 

 according to the character of the l)ath. 



We have introduced important economies over the ordinary 

 methods of separating the two metals, and obtaining the precip- 

 itates. The separation and refining of the metal is eilected in the 

 solution. 



In working the mixed ore of sulphides of lead and zinc, the 

 lead is found as a sulphate in the bottom of the water-tank, and 

 the zinc as sulphate in scdution. 



Not the least interesting ieatures in oxir system ai'e the applica- 

 tion of the pulverized fuel and its economies. There is not only 

 a large economy of heating force, but other consequences which 

 are found to be valuable. 



It is a fair estimate, that, in working copper ores, this method 

 requires not more than one-eighth as much fuel as is required by 

 the so-called English or (ierman methods. 



The eftect of the spray-wheel, which should perhaps be called a 

 water-pulverizer, in wetting down or couilensing dust and fumes 

 that would otherwise escape, should not be overlooked. The 

 general use of it will convert many losses into profits, — the 

 losses made in the ordinary methods of working copper, zinc, 

 and antimony ores for instance, — and by it many serious nuisances 

 will be abated. 



HORSE-POWER. 



Horse-power is a unit of force introduced by Watt, to enable 

 him to deteiTuine what size of engine to send to his customers, to 

 supersede the number of hoi'ses which the new power (steam) 

 was to replace. He ascertained, at a London brewery, that the 

 average force exerted by the strongest horse was sufficient to 

 raise 33,000 j^ounds one foot high in a minute ; thus, an engine 

 of 200 hoi'se-power would be a force equal to that of 200 horses, 

 each lifting 33,000 pounds one foot high per minute. Watt had 

 two methods of estimating and comjjariug his engines, viz., by 

 the poAver, and by the duty. By the jjower is meant the quantity 

 of work which an engine can etieet in a given time ; by the duty 

 is meant the quantity of work which it can etfect by a given ex- 

 penditm-e of fuel. Now, it is evident that, without any change in 



