as a substitute foi- Tea or for the Coffee-bean, 23 



and that tea contains 2 per cent, of the same principle." " And 

 the nitrogen in coffee-beans (see page 27 of the same Report) 

 lies between 2^ and 3 per cent." 



By a recent determination I found that 1000 grains of a good 

 black tea gave 21 '3 grains of theine =2*13 per cent. 



1000 grains of a black tea grown in the East India Company's 

 tea plantations at Kemaon on the Himalayas, gave 19'7 grains 

 = 1'97 per cent. 



0*4705 grm. of the same Kemaon tea gave 0'1175 platinum 

 = 3'5 per cent, nitrogen. 



Many years ago I detected the existence of theine in what is 

 called Paraguay tea, the dried leaves and twigs of the Ilex para- 

 guayensis, but I neglected to detex'mine its amount. I have 

 recently found that 1000 grains of Paraguay tea yielded 12'3 

 grains of theine =1*23 per cent. 



II. 1000 grains ditto gave 11 grains =1'1 per cent. 



1-748 grm. gave 0-1865 platinum =1-51 nitrogen. 



1-031 grm. gave 0'123 platinum =1-70 nitrogen per cent. 



From these results it is clear that dried cofiee-leaves are some- 

 what richer in theine than the coffee-bean, and contain, as nearly 

 as may be, the same amount of that principle as Paraguay tea. 



From the violent roasting to which the coffee-leaves had been 

 subjected, I feel convinced a portion of their theine has been dis- 

 sipated; and were they only dried at a moderate tempera- 

 ture, I confidently expect that they would yield 1^ per cent, of 

 theine. The theine obtained from the coffee-leaves was not 

 subjected to analysis. This I considered unnecessary, as it pos- 

 sessed all the well-known properties of ordinary theine, cry- 

 stallizing in fine silky crystals, which readily sublimed when 

 heated ; and when digested with nitric acid and cautiously eva- 

 porated to dryness, they gave when treated with ammonia the 

 characteristic red coloration so closely resembling that from uric 

 acid when acted on by the same reagents. 



With regard to caffeic acid, the other characteristic proximate 

 principle of coffee, the leaf of the coffee plant contains it also in 

 larger quantity than tlie berry. Caffeic acid is precipitated of a 

 deep yellow colour by acetate of lead, but is apparently uncry- 

 stallizable ; at least the numerous attempts which I have made 

 to obtain it in u crystalline state have hitherto proved unsuc- 

 cessful. Caffeic acid docs not prcci})itate solutions of gelatine, 

 and it is therefore not a sj)ccies of tannin, as has been sometimes 

 asserted. The most remarkable property of caffeic acid is that 

 first stated at the 34th page of the joint lleport on the adultera- 

 tion of coffee already quoted. " Caffeic acid appears to be ana- 



tion," drawn up by Professor Grahiun, Dugsild Canii)bell,',Esq. and myself, 

 for the British Government, and communicated to it in December 1862. 



