as a substitute for Tea or for the Coffee-bean. 35 



Cytisus labw-num, with tobacco, with Prunus spinosa, the sloe, 

 and others too numerous to mention. 



The kinone was only obtained in crystals from the coffee-bean, 

 from the coffee-leaf, and from the holly, the Ilex aquifolium. 

 In all the other cases its existence was detected by the deep 

 yellow liquid which distilled over at a comparatively low tempe- 

 rature, and which yielded the dark humus-like coloration with 

 ammonia, so characteristic of solutions of kinone. Kinone is so 

 exceedingly soluble in water, that unless a considerable amount 

 of it is evolved, and proper precautions are emploj'ed, a deep- 

 coloured solution of it only is obtained either from the coffee- 

 leaf, the berry or the leaves of the holly. The comparatively small 

 amount of the kinone yielding substance, or perhaps we should 

 say substances, present in such plants as the privet, the oak, &c., 

 is most probably the only reason why crystals of kinone have 

 not likewise been obtained from these plants. 



In order to assist in forming an estimate of the comparative 

 value of coffee-leaves as a beverage as compared with the bean, 

 I determined the amount of soluble matter which each of them 

 yielded to boiling water. 6*048 grms. of di'ied coffee-leaves and 

 6"038 grms. of roasted and ground coffee-beans were repeatedly 

 treated with precisely similar quantities of boiling water, till the 

 liquid which came oft' from them was nearly colourless. The 

 6'048 grms. coffee-leaves were found to have lost 2 •348 grms. 

 = 38*8 per cent., while the 6'038 grms. roasted coffee-beans had 

 lost 1'759 grms. =29"! per cent. From this determination it 

 is clear that coffee-leaves yield to boiling water nearly 10 per 

 cent, more soluble matter than the bean. In this respect, there- 

 fore, the coffee-leaf has an advantage over the berry. 



So far as regards the two characteristic principles of coffee, 

 viz. caffeic acid and theine or caffeine, these are common both to 

 the leaf and the bean, the leaf being decidedly richer in both. 

 In other i-espects, however, they differ considerably. The coffee- 

 leaf contains some tannin, and scarcely any sugar or fat. The 

 coffee-bean contains about 12 per cent, of fat and " 8 per cent. 

 of cane-sugar.'" (See Joint Report.) 



So far as I can judge, the infusion of the coffee-leaf has a 

 much greater resemblance to that of tea than to a decoction of 

 the coffee-bean ; so that should the coffcc-leaf ever come into 

 general use in European countries, it will be rather as a substi- 

 tute for tea than for coffee. If the coffee-leaves were only dried 

 at a somewhat lower and better regulated temperature, I have 

 little doubt tbat they would yield a much more agreeable beve- 

 rage than can be made with the present roughly-roasted and 

 partially emjiyreumatized product. 



Chemical Laboiatorj', St. Bartholomew's Hospital, 

 December 1, 1863, 



