548 Chronicles of Science. [Oct., 



has written very fully on those processes, and from his paper we 

 select the following paragraphs : — 



1. " The first step in the treatment of ores is their sub-division, 

 which is effected by two novel and ingenious machines, called 

 respectively the breaker and purverizer. The first of these consists 

 of a horizontal circular table of heavy iron, forty-two inches in dia- 

 meter, revolving about one thousand times in a minute, having 

 bolted to its upper surface four or more radial bars or blocks of 

 chilled iron, and surrounded by a fixed upright perforated screen. 

 The ore, in fragments not more than six inches in diameter, falling 

 into this aperture, is broken by the revolving bars into dust and 

 small grains, which are ejected through the perforated screen or 

 curb, from which the larger particles are thrown back to complete 

 the breaking. Such a machine with fifteen horse-power will break 

 to the size of sand and coarse gravel eighteen or twenty tons of 

 quartz or hard ore per hour. 



" The pulverizer is properly designated as an air-mill, and con- 

 sists of a horizontal shaft, furnished with arms or paddles, which 

 are made to revolve from one to three thousand times a minute, 

 within an inch of the inner surface of a steel-lined cylinder, varying 

 from eighteen to forty inches in diameter. The previously crushed 

 ore is introduced through an opening in the centre of a plate, which 

 covers one end of the cylinder, and is perforated with numerous 

 small holes. 



2. " The calcination of the pulverized ores is effected in what 

 Messrs. Whelpley and Storer call the Water Furnace. This con- 

 sists of a fire-tower, from twenty to thirty feet high, built of brick, 

 with double walls, and somewhat conical in form, being from three 

 to four feet in diameter at the top, and from four to six at the 

 bottom. Around its upper part are built four fire-boxes, opening 

 into the tower near its summit, which is closed and connected with 

 a large fan-blower. By means of this, besides an abundant supply 

 of air, more or less heated by passing between the two walls of the 

 tower, ore and fuel, in the state of dust, are carried downward into 

 the furnace. The effects obtained by the combustion of charcoal or 

 other fuel pulverized and borne in a current of hot air are very 

 surprising. The finely divided combustible being kindled by the 

 flame drawn from the fire-boxes, burns in the descending current 

 with great energy, and from the comparatively large surface exposed 

 to the action of the air, generates a great amount of heat, and, with 

 an excess of fuel, an intense light. The great fiery blast, nearly 

 filling the tower, can at pleasure be made oxydizing or reducing in 

 its action, by regulating the supplies of fuel and of air. I have 

 seen it at twelve feet from the top, so potent as to heat rapidly to 

 whiteness two feet of a wrought-iron bar an inch in diameter, and 

 cause it, though supported at both ends, to bend like wax beneath 



