a mineral Substance from North America. 57 
with great difficulty, when it was again digested with muriatic 
acid. 
3. Prussiate of potash changed the colour of the muriatic 
solution to an olive-green ; the liquor then gradually became 
turbid, and an olive-coloured precipitate was obtained, similar 
to that which has been lately mentioned. But, 
4. If some nitric acid was previously added to the muriatic 
solution, then the prussiate changed the liquor to a grass-green, 
but did not produce any precipitate. 
5. Tincture of galls, in a few minutes, formed an orange- 
coloured precipitate, like that which has been mentioned ; but, 
if the acid was in too great an excess, it wa? necessary to add a 
small quantity of lixivium of potash or soda, before the preci- 
pitate could be obtained. 
6. A small quantity of phosphoric acid, being added to the 
muriatic solution, in a few hours formed a white flocculent 
precipitate. 
7. Potash, soda, and ammonia, also produced white floccu- 
lent precipitates, which were not redissolved by an excess of 
the alkalis, unless the liquors were heated ; and, in that case, 
part was dissolved by the fixed alkalis, but not by ammonia. 
8. The muriatic solution did not yield any precipitate, when 
the muriates of lime, magnesia, and strontian, were added ; but 
muriate of barytes formed a slight cloud. 
9. When a piece of zinc was immersed in the muriatic so- 
lution, a white flocculent precipitate was obtained.* 
This appears to indicate the obstinacy with which this substance retains a certain 
portion of oxygen ; lor we here see that zinc does not precipitate it in the metallic 
state, but only reduces it to an insoluble oxide. 
MBCCCIL I 
