340 Extract from the third Volume of 



When wa^^hcd with water and liUered, the liquor became 

 brown, and contained sulphate of magnesia. 



A liundred grair.s ot un)ber earth reduced to fine powder, 

 and digested with boiling muriatic acid, left a residuum 

 which ^\ eighed 19 grams: The solution when filtered w&i 

 condensed by evaporation, and mixed with a concentrated 

 solution ot tai trite of potash; but the mixture remained 

 clear. M. Klaproth then endeavoured to obtain a precipi- 

 tate by the solution of caustic soda, but did not succeed : he 

 even did net cbserve any cloud, and the saturated soluiiou 

 assumed a reddish browi^ colour. Ke poured into it mu- 

 riatic acid, and the colour of the solution was heightened : 

 he then tried, but without success, to precipitate it by am- 

 monia; ibr the mixture reappeared with the brownish red 

 colour before indicated, and without any cloud. 



M. Klaproth's object was to separate the manganese 

 from the iron by means of these reagents ; but this trial 

 only confirmed a peculiar property of the tartareous acid, 

 which is, that by its presence it renders iron soluble in alka- 

 line solutions. 



A hundred grains of pulverized umber earth were mixed 

 with a solution of 200 grains of caustic soda, then desic- 

 cated to dryness, and exposed in a crucible to a moderate 

 fire for half an hour. Tlie mass dissolved in the water ga\-e 

 "it a beautiful dark emerald green colour, which became of 

 an amethyst red by the addition of muriatic acid. This 

 acid added to saturation dissolved completelv, and the li- 

 quor had acquired a red colour inclining to yellow. There 

 were disengaged at the same time vapours of oxvgenated 

 muriatic acid. The solution, when evaporated alniost to 

 dryness, assumed at last the form of a jellv : diluted with 

 new water, it left on the filter silex, which when well dried 

 weighed 13 grains. 



2d. AI. Klaproth poured into the liquor a solution of 

 caustic soda, which he added in ex'cess, and the brown oxide 

 of iron precipitated by it was washed. The ren>aining so- 

 lution was precipitated by sulphuric rcid, and neutralized by 

 carbonate of potash: alumine was-<lepositcd, which when 

 dried weighed .5 grains. 



3d. The oxide of iron after beincj dried was black and 

 br lliant,andreseml)k'd a piece of coat: it weighed 68 grains. 

 R. dissolved in muriatic acid added onlv to the point of sa- 

 t-iration, it was precipitated from it by the succinate of am- 

 monia. The rest of the solution become colourless, mixed 

 with the abundant water arisino; from the washino; of the 

 tiaUy deposit of non_, was again precipitated by that ot 



3 caustic 



