1 12 Mr. Smithson on the colouring 
This matter heated in a platina spoon over a candle, tume- 
fied considerably, as much as starch does, became black and 
smoked, but did not readily inflame, nor did it burn away till 
the blowpipe was applied. It then burned pretty readily, 
leaving a largie quantity of a white saline matter. This saline 
matter saturated by nitric acid afforded crystals of nitrate of 
potash, and some minute crystals like hydrous sulphate of 
lime. 
Is this potash merely that portion of this matter which 
exists in all vegetable substances ? or is the colouring matter 
of turnsol a compound, analogous to ulmin, of a vegetable 
principle and potash ? Its low combustibility gives some 
sanction to this idea. 
Of the colouring matter of the violet. 
The violet is well known to be coloured by a blue matter 
which acids change to red ; and alkalies and their carbonates 
first to green and then to yellow. 
This same matter is the tinging principle of many other 
vegetables : of some, in its blue, state ; of others, made red 
by an acid. 
If the petals of the red rose are triturated with a little 
water and carbonate of lime, a blue liquor is obtained. Alka- 
lis, and soluble carbonates of alkalis, render this blue liquor 
green ; and acids restore its red colour. 
The colouring matter of the violet exists in the petals of 
red clover, the red tips of those of. the common daisy of the 
fields, of the blue hyacinth, the holly hock, lavender, in the 
inner leaves of the artichoke, and in numerous other flowers. 
It likewise, made red by an acid, colours the skin of several 
