For this reason those barks which, like C. Calisaya, C. officinalis, and C. Ledgeriana, contain but little colouring matter are preferred, the quinine being more easily extracted from them in a colourless form.
I'll keep that in mind the next time the sergeant barks at me.
Commercial sulphate of quinine frequently contains from I tc 10% of cinchonidine sulphate, owing to the use of barks containing it.
The first importation from India took place in 1867, since which time the cultivated bark has arrived in Europe in constantly increasing quantities, London being the chief market for the Indian barks and Amsterdam for those of Java.
Some years ago it was discovered that a bark imported from Colombia under the name of cuprea bark, or "hard" bark, and derived from Remijia pedunculata, Triana, and other species, contained quinine to the extent of 4 to 22%, and in 1881 this bark was exported in enormous quantities from Santander, exceeding in amount the united importations of all the other cinchona barks;: and by reason of its cheapness this has since that date been largely used for the manufacture of quinine.