936 Tj?axsacttoxs of the American Institute. 



Canada, had found that when tlie sand was poured in a thin stream 

 upon the apex of a cone, and suffered to flow down its surfoce, the 

 lighter particles of sand would drop from the lower edge in a nearly 

 Tertical direction, while the ore grains, having a much greater 

 specific gravity, and requiring a much quicker velocity in passing 

 downward upon the surface of the cone, would pass from the latter 

 in lines more directly in line with the surface thereof; the two 

 materials being thus made to diverge in leaving the cone, and conse- 

 quently being separated. In order to carry out the idea broached 

 by Mr, Holmes, and with his cognizance and approval, he (Mr. W.), 

 had devised a system of ore separating mechanism. It involved a 

 vibrating chute of sheet metal, heated by a furnace to dry the sand 

 passing over it. A conical guide to conduct the stream of sand from 

 the chute to the apex of the uppermost cone, and a series of cones 

 and funnels or guides placed one over the other, in such a w^ay that 

 the ore extracted from the sand in passing over an upper cone would 

 be conducted to a lower one, where remaining sand would be sepa- 

 rated, and so on over a succession of the cones until the whole of the 

 sand had been eliminated. As an illustration of the manner in which 

 the same thing is frequently invented by different persons, wholly 

 independent of each other, he mentioned that within tlie past few 

 months a patent has been granted in England upon a machine appa- 

 rently identical in principle with that just descril)ed. 



Mr. T. D. Stetson remarked that he was familiar with the history 

 and modus operandi of this machine, and thought Mr. Krom was 

 entitled to credit for the patience and persistence with which he had 

 brought the principle into practical working form. The separation 

 of particles of different specific gravity by an air current, as for 

 instance, in winnowing grain, is different from the same process car- 

 ried on by nie;ins of water, us in ordinary ore separations, in which 

 the material moves slowly through a long vat. In this case the 

 coarser particles settle first, and the separation is more by size than 

 weiirht. These are, indeed, the two conditions which determine the 

 assortment ; one is specific gravity, and the other is size. If the 

 grains are all of a size and form, as a very slight difference in the 

 gravity may assort by ordinary winnowing ; but if, as is always the 

 fact in practice with crushed and broken grains, there are an indefi- 

 nite variety of sizes, then the finer of the heavy particles will go 

 •over and lodge with the light, and the coarse of the light material 

 vwill fall with the heavy. Mr, Krom's machine embodies a very 



