( 276 ) 



ing is a description : — Suppose a cylinder to be formed of bars of iron 

 longitudinally placed, and nailed to circles of wood, open at each 

 end, and suspended on two centres, one about sixteen inches higher 

 than the other. At the highest end the cascalhao is to enter by being 

 put into a hopper which communicates with it. The bars must be 

 nailed almost close to each other at the upper end, gradually widen- 

 ing to the lower end, where they should be about half an inch asun- 

 der. The cylinder ought to be from ten to fifteen feet long, and a 

 stream of water conducted to fall upon it length-wise : it should be 

 inclosed, like a dressing-machine in a flour-mill, and be subjected to 

 a very quick motion. The portion of cascalhao containing the most 

 gold will by gravity fall through near the upper end ; the other parts, 

 according to their comparative fineness, gradually descending until 

 nothing but the pebbles fall out at the lower end. The earth and 

 ferruginous oxide, falling into partitions or troughs below the cylin- 

 der, would be ready for being purified or separated from the gold by 

 hand, which might be done with very little trouble. — Machines of 

 this kind might be made on any scale, and, if generally known and 

 adopted, would save the labour of the negroes in a ten-fold degree. 

 The one constructing in Cerro do Frio will, when complete, do more 

 work than a hundred negroes in the same space of time. A considerable 

 improvement might yet be made in this useful apparatus ; for, if the 

 gold, &c. washed from the machine were to fall upon troughs placed 

 in an inclined position, having a channel across about a yard from 

 the upper end*, all the gold would precipitate into it, and, if a negro 

 were to be continually employed in agitating the water, the earthy 

 matter would run off, leaving only the gold and the ferruginous par- 

 ticles, which might be easily separated by mercury The utility of 

 machinery of this kind is too obvious to need pointing out. 



* If necessary, another channel might be made at a convenient distance from the first. 



f It cannot be too much recommended to Government to introduce the process of amal- 

 gamation generally throughout the mines. 



