Chemistry. Ixxuil 
precipitate in aqueous solution of carmine if no animal substance 
be present. It is, therefore, a useful reagent to enable us to 
discover the presence of animal matter in this colouring principle. 
Iodine acts in the same way as chlorine, but with less rapidity. 
When the alkalies are poured into a solution of carmine, they 
give it a violet colour. If the alkali be saturated immediately, 
the original colour appears, and of course the carmine remains 
unaltered, or at least only slightly modified ; but if the action of 
the alkali be prolonged, or if it be augmented by the application 
of heat, the violet colour is dissipated, the liquid becomes first 
red, and then yellow. The nature of the colouring matter is now 
completely altered. 
- Lime-water occasions a violet-coloured precipitate when drop- 
ped into the aqueous solution of carmine. Barytes and strontian 
occasion no precipitate, but produce the same change of colour 
as the alkalies... Alumina has a very strong affinity for carmine. 
When newly precipitated alumina is put into an aqueous solution 
of carmine, the liquid is totally deprived of its colour, and the 
alumina converted into a beautiful lake. If a few drops'of acid 
be added to the aqueous solution before adding the alumina, the 
lake obtained has a fine red colour as before; but it becomes 
violet upon the application of the least heat. The same effect is 
produced by adding to the liquid a few grains of an aluminous 
salt. 
Most of the saline solutions alter the colour of the aqueous 
solution of carmine ; but few of them are capable of producing a 
precipitate in it. The salts of gold alter the colour merely ; 
nitrate of silver produces no change whatever ; the soluble salts 
of lead render the colour violet ; and acetate of lead occasions a 
copious violet precipitate. By decomposing this precipitate by 
means of a current of sulphuretted hydrogen, we may obtain the 
carmine dissolved in water in a state of purity. 
Protonitrate of mercury throws down a violet precipitate. 
Peritrate of mercury does not act so powerfully, and the colour 
of the precipitate is scarlet. Corrosive sublimate produces no 
effect whatever. ‘ 
Neither the salts of copper nor of iron occasion any precipitate ; 
but the former changes the colour of the liquid to violet, the 
latter to brown. 
Protomuriate of tin throws down a copious violet precipitate. 
The permuriate changes the colour to scarlet, but produces no 
precipitate. When gelatinous alumina is added to the mixture, 
we obtain a fine red precipitate, which is not altered by boiling. 
None of the aluminous salts occasion a precipitate, but they 
change the colour to carmine. ‘The salts of potash, soda, and 
ammonia, change the colour of the liquid to carmine red. 
From the action of the different salts upon this colouring mat- 
ter, Pelletier and Caventon have drawn as a conclusion that the 
metals susceptible of different degrees of oxygenation act like 
