184 An Analysis of two Mineral 
with the manganese, as might be expected from the 
affinity between the oxyds of these metals: for, by 
fusing the precipitate with nitre, green spots were 
formed on the sides of tie crucible. 
Tartrite of potash decomposes likewise salts of 
lime, as is well known; but the tartrite of lime is 
precipitated in the form of a white powder which is 
not sensibly crystalline. But, as there is a great 
abundance of lime in this water, (xiv.) it seems 
probable that it had entered into the composition of 
these crystals. 
Manganese has been but rarely noticed as enter- 
ing into the composition of mineral waters, The 
reason, perhaps, is, that it has been seldom looked 
for, rather than that it seldom exists; since it is now 
known to be a substance very abundantly diffused 
through the earth. The waters of Astrop, which I 
have mentioned above (111. 2.), decompose tar- 
trite of potash and form a crystalline precipitate, 
when its carbonat of lime has been thrown down by 
boiling. This water, in ese circumstances, hardly 
affects either tincture of galls or prussiat of potash. 
Every chalybeate spring may be suspected to con- 
tain some manganese likewise; and should, there- 
fore, be examined accordingly. 
VI. TESTS OF MANGANESE AND IRON, 
As I shall have frequent occasion to mention 
this mixture of the oxyds of manganese and iron, I 
