254 ANALYSIS of a BLACK SAND 



rate. But after all that can be attracted by the magnet is re- 

 moved, the greater part of the black powder ftill remains. This 

 refidue is indeed attracted by a powerful magnet, but fo very 

 feebly, that it is not poffible by means of it to feparate it from 

 the grains of fand with which it is mixed. Thus we learn, that 

 the black matter confifts of two diftind fubftances ; one of 

 which is powerfully attracted by the magnet, the other not. 

 As this fecond fubftance was obvioufly fpecifically heavier than 

 the grains of fand with which it was mixed, I placed a quanti- 

 fy of the powder on an inclined plane, and by expofing it cau- 

 tioufly, and repeatedly, to a jet of water, I fucceeded in warning 

 away mofl of the grains of fand, and thus obtained it in a flate 

 of tolerable purity. 



The firft of thefe minerals we may call iron-sand, and the 

 fecond iscrine, as they belong to mineral fpecies which oryc- 

 tognofts have diftinguifhed by thefe names. 



r 



I. IRON-SAND. 



i 

 The iron-fand is much fmaller in quantity than the iferine, 

 and does not exceed one- fourth of the mixture at mofl. Its co- 

 lour is iron-black. It is in very fmall angular grains, common- 

 ly pretty fharp-edged, and fometimes having the fhape of im- 

 perfect; octahedrons. The furface is rough ; the lullre is feebly 

 glimmering and metallic ; the fracture, from the fmallnefs of 

 the grains, could not be accurately afcertained, but it feemed to 

 be conchoidal. Opake, femihard, brittle, eafily reduced to pow- 

 der. Powder has a greyifh-black colour ; powerfully attrac- 

 ted by the magnet j fpecific gravity 4.765. 



I. As acids were not found to act upon this mineral, 100 

 grains of it were reduced to a fine powder, mixed with twice 



its 



