292 On the Cause of the Changes 
3. I have prepared the cameleon of which I have made use, 
by exposing in a crucible of platinum to the action of a red heat 
for twenty minutes, a mixture of a gramme (about a scruple) of 
oxide, red-brown, obtained by the calcination of the carbonate 
of pure manganese with eight grammes of potash. The green 
mass produced by this operation was twelve hours afterwards 
immersed in water. Whatever was the proportion of water em- 
ployed, there was always a large enough quantity of the oxide 
which did not dissolve. I do not think that the whole of the 
oxide has ever been separated by the action of the water; I be- 
lieve that there is a portion of it, which, after being incorporated 
with the alkali, separates itself from it upon the solidification of 
the cameleon by cooling. ‘This last portion appears often under 
the form of little brilliant spangles, similar to the sulphuret of 
molybdenum. 
4. When the cameleon dissolved in water passes to blue, it is 
not by depositing from the oxide of iron yellow ; for cameleon 
which has been prepared with the pure oxide of manga- 
nese yields a similar deposit, and the liquid when perfectly 
clear, being evaporated to dryness, leaves a residue, which takes, 
when it is exposed to a red‘heat, a beautiful green colour, and 
communicates the same to water when immersed init. Now, if 
the colour of cameleon was naturally blue, it ought to be ob- 
tained of that colour, upon dissolving with potash the oxide 
which has been deprived of its pretended oxide of iron. Either 
then the colour of cameleon is not blue, or the observation of 
Scheele is not proved. 
5. When cameleon passes more or less slowly from green to 
red, it presents a series of colours in the order of the iris ; viz. 
green, blue, violet, indigo, purple, red. Not only cold water, 
but even carbonic acid, carbonate of potash, subcarbonate of 
ammonia, and lastly hot water, when added to cameleon, pro- 
duce these colours. It is observed that the latter even produce 
them with more rapidity than cold water. 
6. According as it appears to me, the green solution of came- 
leon is the combination of caustic potash with the oxide of man- 
ganese, and the solution which becomes red by carbonic acid 
(of which alone I at present speak) is a triple combination of 
potash, the oxide of manganese, and carbonic acid. It may be 
also necessary to take account of the water which holds these. 
combinations in solution; but the proportion of water does not 
seem to me to have any sensible influence on their coloration ; 
for if we saturate with carbonic gas, a green solution, formed of 
one part of cameleon and ten parts of water, it will pass to red, 
depositing at the same time a little of the oxide; then on putting 
into this red liquor some dry caustic potash it resumes the green 
colour ; 
