of Colour in Mineral Cameleon. 293 
eolour;: and afterwards, on saturating the alkali added by the 
carbonic gas, the red colour is reproduced, accompanied with a 
deposition of a little of the oxide. In the last place, I have ob- 
served that precipitating by the water of barytes a part of the 
carbonic acid from a red solution of cameleon, changes it into 
green cameleon*, 
7. Cameleons which become blue, violet, indigo, and purple, 
by the action of carbonic acid, appear to me to be mixtures of 
green and red cameleon. In proportion, accordingly,as we add 
more and more considerable quantities of green cameleon, we 
obtain successively purple, indigo, violet, and blue liquids. It is 
easy from this to conceive, how by adding at intervals to a green 
eameleon some small quantities of earbonie acid or carbonate of 
potash, blue, violet, indigo, and purple liquids will be obtained ; 
and again, how the liquids may be obtained in the inverse series, 
by adding, at intervals, to a red cameleon sinall quantities of 
potash. 
8. Let us now endeavour to prove by analysis the nature of 
the intermediate cameleons between green and red. If we filter 
some green cameleon a certain number of times upon a filtert of 
sufficient size, the cameleon will be deeomposed into potash, 
which will remain in the water, and into oxide of manganese of 
a brownish yellow, which will attach itself to the slips of paper, 
in virtue of an affinity analogous to that which occasions the 
combination of cloths with the mordants employed in dyeing. 
A similar decomposition will take place, if we introduce a piece 
of paper into a solution of green cameleon, separated from all 
contact with the air;—the reswits are the same with red cameleon. 
The chemical action of paper on solutions of cameleon being 
thus demonstrated, the possibility may be conceived of reducing 
by filtration a liquor containing the two cameleons to a simple 
solution of one of them, provided there exists always a difference 
in the tendeney which the oxide of manganese of the green 
combination and the carbonated combination have to unite 
with the paper; and so in fact we find the case to-be: for if we 
filter blue, violet, indigo, and purple eameleons, the red cameleon 
is decomposed, while the green cameleon passes to the side of 
the filter. 
9. The preceding explanation is applicable to changes pro- 
* It is not necessary to use as much of the barytes as will saturate all the 
earbouic acid; for it would precipitate with it a rose-lilac combination of 
the oxide of manganese and barytes. ‘Uhis combination, which is a species 
of cameieon, may perhaps be spoiled by the submixture of acetic acid of 
cartionate, which there is no doubt exists in compounds of this sort, 
¥ Which ought to be washed with hydrochloric acid, to prevent any 
foreign matters from attaching to 4 slips of paper, 
7 
duced 
