OQ fiLACK SAND ON THE BANKS OF THE DON. 



cal chemistry, to manage an analysis of any considerable 



difficulty, 

 mixed with tha The black powder is mixed with a good many small, 

 detritus of gra- ^^j^i^i^j,^ reddish, and brownish grains, which, when exa- 

 nite or gneiss, • , , r i ^ i • r * 



mined by means ot a glass, prove to be pieces ot quartz, 



felspar, and mica. From this it would appear, that the 

 sand of the river Don consists chiefly of the detritus of gra- 

 nite or gneiss. 

 and consisting When a magnet is passed over the sand, some of the 

 stance-: black grains adhere to it, and are by this means easily ob- 



tained separate. But after all that can be attracted by the 

 magnet is removed, the greater part of the black powder 

 still remains. This residue is indeed attracted by u power- 

 ful magnet, but so very feebly, that it is not possible by 

 means of it to separate it from the grains of sand with which 

 it is mixed. Thus we Itarn, tjhat the black matter consists 

 of two distinct substances; one of which is powerfully at- 

 tracted by the magnet, the other not. As this second snb- 

 stance was obviously specifically heavier than the grains of 

 sand with which it was mixed, I placed a quantity of the 

 powder on an inclined plane, and by exposing it cautiousl}', 

 and repeatedly, to a jet of water, I succeeded in washing 

 away most of the grains of sand, and thus obtained it in a 

 state of tolerable purity, 

 iron-sand and The first of these minerals we may call iron-sand^ and the 

 iseri e. second iserinei as they belong to mineral species, which 



orjTtogi.osts have distinguished by these names, 

 'i hf iron-sand The iron-sand is much smaller in quantity than the ise- 

 *^" * * rine, and does not exceed one fourth of the mixture at 

 mo&t. Its colour is iron-black. It is in very small angular 

 grains, commonly pretty sharp edged, and sometimes hav- 

 ing the shape of impeifect octaedions. The stirface is 

 rough; the lustre is feebly glimmering and metnllic; the 

 tVaclvire, from the smallness of the grains, could not be ac- 

 curately ascertained, but it seemed to be couchoidal. 

 Opake, semihard, brittle, easily reduced to po\vder. Pow- 

 . d^^r has a grayish black colour; powerfully attracted by the 

 inagn«»t; specific gravity 4*7G5. 

 Ait-lyiis of it. ; !• Ab Qcids were not found to act upon this mineral, 100 

 grains of it were reduced to a tine powder, mixed with 



twice 



