Mr. J. T. Cooper on Catechuic Acid. 501 



it is nearly insoluble, until the water passes through colour- 

 less, or very nearly so, and then dried slowly by exposure to 

 a gentle heat; in this manner the specimen herewith presented 

 to the Society has been prepared, and which, if examined, will 

 be found to possess the properties described as appertaining 

 to catechine, catechuic, or tanningenic acids, namely, a white 

 substance with a light tint of reddish-brown, a glistening or 

 micaceous aspect when diffused in water, meagre to the feel, 

 something like alumina, insolubility in cold water, and ready 

 solubility, to a great extent, in hot water; forming a brown 

 solution of greater or less intensity in proportion to the quan- 

 tity dissolved ; readily soluble in alcohol and aether, and in 

 the weakest alkaline solutions, without the assistance of heat, 

 forming brown compounds ; and with the assistance of heat 

 becoming dark brown, or almost black, owing, it is said, to 

 the absorption of oxygen from the atmosphere, and its con- 

 version into what is called japonic acid, fusible per se into a 

 resinous looking substance by the cautious application of heat, 

 and if heated much beyond its fusing point becoming charred, 

 leaving a very bulky charcoal. 



If it be considered desirable to undertake the organic ana- 

 lysis of this substance, in all probability the specimen presented 

 may require further purification, and by adopting the process 

 recommended by Svanberg, namely, forming it into a cate- 

 chuate of lead, and decomposing this by sulphuretted hydro- 

 gen while warm, may in the hands of others be effectual for 

 the purpose, but I confess it has not succeeded well with me. 



Catechu. 

 12-3 Water. 

 62-8 Tannin. 



8 '2 Extractive or colouring matter. 



2* Resinous matter. 



8*5 Mucilaginous or gummy matter. 



4.'4 Insoluble matter. 



Cutch. 



12-8 Water. 



Mm a rr. • f41-5 tannin. 



47-7 Tannin | 6 . g aUered tannin> 



9*2 Extractive or colouring matter. 

 13*6 Mucilaginous or gummy matter. 



6-8 Resinous matter. 



9*4 Insoluble matter. 

 99^5 



