100 ' Anahjsis of a Black Sand^ 



ceparate a reddish -brown matter, which had been precipi- 

 tated. The clear hquid which passed through the filter 

 was mixed with a solution of sal ammoniac. A soft white 

 matter slowly subsided. It was alumina, and, after being 

 heated to redness, weighed half a grain. 



8. The brown -coloured matter which had been precipi- 

 tated by the potafh, when dried upon the steam-bath, 

 weighed 20*2 grains. It dissolved with effervescence in 

 muriatic acid. The solution had the appearance of the yolk 

 of an egg. When boiled for some time, and then diluted 

 with water, it became white, and let fall a curdy precipi- 

 tate, which weighed, when dry, 4*6 grains, and possessed 

 the properties of oxide of titanium. 



9. The residual liquor being mixed with an excess of am- 

 monia, let fall a brown matter, which, after being dried, 

 drenched in oil, and heated to redness, weighed six grains. 

 It was strongly attracted by the magnet, but was of too 

 light a colour to be pure oxide of iron. I therefore dis- 

 solved it in muriatic acid, and placed it on the sand-bath, 

 in a porcelain capsule. When very much concentrated by 

 evaporation, small while needles began to make their ap- 

 pearance in it. The addition of hot-watei made them dis- 

 appear j but they were again formed when the liquor be- 

 came sufficiently concentrated. These crystals, when se- 

 parated, weighed 1'3 grains, and proved, on examination, 

 to be white oxide of arsenic. During the solution of the 

 six grains in muriatic acid, a portion of black matter sepa- 

 rated. It weighed 0*2 grains, and was totally dissipated 

 before the blow- pipe in a white smoke. Hence, it rausi 

 have been arsenic. These 1'5 grains are equivalant to ra- 

 ther more than one grain of metallic arsenic. Thus, it ap- 

 pears, that the six grains contained one grain of arsenic, 

 •which explains the whiteness of their colour. The rest was 

 iron. It can scarcely be doubted, that the proportion of 

 arsenic present was originally greater. Some of it must 

 have been driven ofi' when the iron oxide was heated with 

 oil. 



10. Th« insoluble residue (No. 4.) was with great diffi- 

 culty dissiolved in sulphuric acid. When the solution was 

 mixed with ammonia, a white powder fell, which weighed 

 0*8 grains. It was accidentally lost, before I examined its 

 properties. But I have no doubt, from its appearance, that 

 It was oxide of titanium. 



11. Thus, from the 100 grains of iron-sand, the follow* 

 ing constituents have been extracted by analysis ; 



Black 



