H5 
matters of some vegetables. 
Sulphuric acid rendered all the above mixtures florid red. 
It is remarkable that the mixtures with ammonia, and carbo- 
nate of ammonia, which were become quite vinous red by 
standing, were made a perfect blue by the sulphuric acid 
before they were reddened by it. It would hence seem that 
the red colour, caused by these alkalis, was owing to an 
excess of them ; and that in a less quantity they would have 
produced a blue. 
The filter, into which the mixture of mulberry juice and 
chalk had been thrown, was become tinged blue. Water 
did not remove this colour. Sulphuric acid made this paper 
florid red. Caustic potash did not alter its blue colour ; but 
put on the places made red by sulphuric acid, it restored the 
blue colour, but did not produce green. 
Future experiments must decide whether this blue matter 
is the same as that of turnsol ; or as the blue matter which 
the experiments above have indicated in sugar-loaf paper. 
The juices of many other fruits, as black cherries, red cur- 
rants, the skin of the berries of the buckthorn, elder berries, 
privet berries, &c., seem to be made only blue by mild fixed 
alkalis, but green by caustic. Puzzling anomalies, however, 
occasionally present themselves, which seem to show a near 
relation between the several blue colouring matters of vege- 
tables, and their easy transition into one another. 
The corn poppy. 
The petals of the common red poppy of the fields rubbed 
on paper stain it of a reddish purple colour. 
Solution of carbonate of soda put to this stain occasioned 
but little change in it. 
