224 PREPARATION OP OUTCn AND KklTttAi 



and, therefore, money, but also give only the purest products nl 

 the largest quantity obtainable. Dr. Warth recommends the 

 following process : — Shave the wood fine (about one-sixteenth of 

 an inch thick) on a lathe, steam the shavings in special copper 

 pans and boilers, cool the extract to precipitate the catechin, get rid 

 of the liquid portion in a filter press, and finally dry, in vacuum 

 pans, both the filtrate and what remains on the filter, the former 

 yielding the tannin, the latter the catechin. 



Dr. Warth has proved that catechin is very quickly decomposed 

 when in a state of solution. Even pure catechin, dissolved in 

 water and at once recrystallised, loses, on an average,' 32 per 

 cent, of its original weight. Dr. Warth has also shown that cate- 

 chin is soluble only in hot water, whereas tannin is soluble at all 

 temperatures ; and that whereas, when in solution by itself, cate- 

 chin separates from the liquid without any delay if the solution is 

 cooled down suflBciently, it takes days to be precipitated, under 

 mere exposure to air, if tannin is also in solution with it. This 

 demonstrates the necessity of shortening the process of manufac- 

 ture as much as possible. Hence the necessity of steaming instead 

 of boiling, and of the filter press and vacuum pans instead of slow 

 precipitation and evaporation in open vessels or moulds. Bazar 

 kattha made in Oudh, analysed by Dr. Warth, yielded on recrystalli- 

 sation an average of only 36 per cent, of catechin, whereas by Dr. 

 Warth's process the extract would be pure, or very nearly pure, 

 catechin. 



Although catechin decomposes so easily in solution, yet in its 

 crystallised form it will keep unchanged for years. Hence the 

 practice of selling it in the bazars in a liquid form is a bad one. 



The market for both cutch and kattha being, in comparison with 

 our forest resources, practically unlimited, there is no reason, with 

 fairly high ruling prices, why in one and the same forest both 

 cutch and kattha should not be made together, as suggested by 

 Dr. Warth. By this means, all the khair trees of a coupe would 

 be utilized, instead of, as at present in the case of kattha manufac- 

 ture, only those which exhibit numerous white markings. In this 

 way, the present enormous waste of khair trees would be stopped 

 and the value of the khair forests at once increased two to ten-fold. 



In Dr. Warth's experiments well-marked Oudh wood yielded 9 

 per cent, of catechin and 15 per cent, of tannin, while wood re- 

 jected by the kattha boilers contained 3-7 per cent, of catechin and 

 12 per cent, of tannin ; on the other hand, of the Burmese wood 

 the unmarked variety gave only 2 per cent, of catechin and 14 per 

 cent, of tannin, while the most conspicuously marked specimens 



