71 
great hilarity of spirits, and such an agreeable state of wake- 
fulness, that the Arabs who chew them are able to stand 
sentry all night long without feeling drowsy. 
As the properties of kat resemble so much those of tea, 
it appeared to me highly probable that they contain caffeine. 
My friend, Mr. H. Marshall Ward, was kind enough to 
apply to Professor W. T. Thistleton Dyer, F.RS., who 
supplied me in the beginning of December with fresh leaves 
of a plant growing in the temperate house at Kew Gardens. 
He also sent me a sample from the museum. He says 
“ The material in our museum is not very satisfactory, but I 
enclose a portion of an authentic sample. The leaves are 
different in form from those of the living plant, but I have 
ascertained that in this respect they are variable.” 
I first examined the fresh leaves ; not a trace of caffeine 
could be found, while its presence can be easily shown in 
three or four tea-leaves. The only crystalline compound 
which I could extract from Catha was a kind of sugar, 
apparently Mannite. The quantity was, however, too small 
for identifying it. 
No caffeine could be detected in the authentic sample, 
but it contained common salt, showing that it must have 
been in contact with sea water. 
As I fully expected to find caffeine and was disappointed, 
it occurred to me that possibly the leaves of tea and coffee 
grown at Kew might also not contain their characteristic 
principle. 
Professor Dyer kindly supplied me with the fresh leaves 
of several varieties and species in the middle of February. 
I found caffeine in green tea (Thea viridis ) and in Assam 
tea ( T . assamica). 
The leaves of Cojfea arabica, which is now fruiting in 
the gardens, contain it also, but much less in proportion 
than tea. 
