ACCOUNT OF A MINERAL SUBSTANCE. 177 



I. 



Before I conclude this fection, I muft obferve, that when The precipitates 

 the olive-green precipitates, obtained by pruffiate of potafti, ^g^ompoffd 

 weredigefted in an alkaline lixivium, they were decompofed ; by humid alkali, 

 for the alkali combined with the pruffic acid, and with afmall f lich tou }\ U P, 

 part of the white matter; but the greater part of the latter a |j tt ] e f the 

 remained undiilblved, in the fame white flocculent ftate which white matter, 

 was noticed when the alkaline combinations were mentioned. 



The orange-coloured precipitates, formed by tincture of 

 galls, were alfo decompofed when digefled in boiling nitric 

 acid ; and the white matter was recovered in its original ftate. 



§ III. REMARKS. 



The preceding experiments mew, that the ore which has Obf. The ore 

 been analy fed, coniifts of iron combined with aiv unknown ^ree^'arts of 

 iubftance, and that the latter conftitutes more than three- the white mat- 

 fourths of the whole. This fubftance is proved to be of a Jjf* . M . 



1 ... The latter is me- 



metallic nature, by the coloured precipitates which it forms tallic; for it is 

 with prufliate of potafli, and with tin6ture of galls ; by the P/ eci P- ^ P ruf * 

 eflects which zinc produces, when immerfed in the acid folu- g^^ an d by 

 lions ; and by the colour which it communicates to phofphate zinc > anJ itc p- 

 of ammonia, or rathor to concrete phofphoric acid, when melt- by f u f ion l 

 ed with it. 



Moreover, from the experiments made with the blow-pipe, It is of difficult 

 it feems to be one of thole metallic fubftances which retain redu " 10n > 

 oxigen with great obftinacy, and are therefore of difficult re- 

 duction. 



It is an acidifiable metal ; for the oxide reddens litmus and acidifiable. 

 paper, expels carbonic acid, and forms combinations with the 

 fixed alkalis. But it is very different from the acidifiable me- 

 tals which have of late been difcovered ; for, 



1. It remains white when digefted with nitric acid. Differs from all 



2. It is foluble in the fulphuric and muriatic acids, and able^meulT/in ' 

 forms colourlefs folutions, from which it may be precipitated, the properties 

 in the ftate of a white flocculent oxide, by zinc, by the fixed ^f^™™' 

 alkalies, and by ammonia. Water alfo precipitates it from the 



fulphuric folution, in the ftate of a fulphate. 



3. Pruiliate of potafh produces a copious and beautiful olive- 

 green precipitate. 



Vol II.— July, 1802. N 4. Tin&ure 



