GUARANA 155 



discharge the ripe seeds they are collected, and the seeds, which 

 resemble small horse-chestnuts in shape and colour, are separated by 

 shelling. They are first washed and then roasted to loosen them 

 from a papery shell, from which they are freed by beating. The 

 broken kernels are made into a dough with water ; this is then divided 

 into masses of varying size and shape, sometimes representing a fish 

 or other animal, which are finally dried at a gentle heat by means of 

 a slow fire. From the hard mass thus obtained portions are grated 

 off with a large file and served in glasses of water, forming a refreshing 

 drink. 



Description. Guarana commonly appears on the market in the 

 form of extremely hard, heavy, sausage-shaped masses, varying 

 from 10 to 30 cm. in length and from 2'5 to 4 cm. in thickness. The 

 outer surface is dark chocolate brown in colour, and would be smooth 

 and uniform were it not that small angular fragments, often of lighter 

 colour than the rest, project slightly ; these fragments are evidently 

 the larger pieces of the broken seed. The fractured surface, smoothed 

 with a knife, is reddish in colour, and exhibits, like the outer surface, 

 small paler irregular fragments embedded in a darker reddish mass, 

 but no definite structure is discernible. The powder, in which form 

 the drug is administered, is of a pale red colour ; it has a scarcely 

 perceptible Odour and slightly astringent, bitter taste. 



The student should observe 



(a) The extremely hard heavy masses in which the drug 



occurs, 

 (6) The presence of small, paler fragments embedded in 



them. 



Constituents. Guarana contains from 2-5 to nearly 5 per cent, of 

 caffeine, together with a little catechu-tannic acid. There is abund- 

 ance of starch present also, but only a little fat. 



Adulteration. The detection of foreign substances in such a drug 

 as guarana is attended with considerable difficulty. The amount of 

 caffeine should not be less than 2*5 per cent. Microscopical 

 examination has shown the presence of the seed-coats, which therefore 

 are only imperfectly separated, and frequently of foreign starches ; 

 the latter, according to Schar (1897), are regularly present. Thorns 

 (1894) found in guarana 8'63 per cent, of moisture, 1-68 per cent, of 

 ash, and 2-68 per cent, of caffeine, the seeds themselves yielding 

 closely concordant figures. 



Uses. Guarana is employed as a nervine stimulant in the same 

 way that tea and coffee are, and produces similar effects. It has 

 been long in common use in Brazil. 



