81 



J 



that principle ; its fibrous texture and coherence are 

 preserved ; it is rendered perfectly insoluble in water, 

 and is no longer liable to putrefaction : in short, it 

 becomes a substance in chemical composition pre- 

 cisely analogous to that furnished by the solution of 

 jelly and the solution of tannin. 



In general, in this country, the bark of the oak 

 is used for affording tannin in the manufacture of 

 leather ; but the barks of some other trees, particu- 

 larly the Spanish chesnut, have lately come into use. 

 The following table will give a general idea of the re- 

 lative value of different species of barks It is founded 

 on the result of experiments made by mysSlf. 



Table of Numbers exhibiting the quantity of Tannin af- 

 forded by 480/bs. of different Barks, which express 

 nearly their relative values. 



The quantity of the tanning principle in barks 

 differs in different seasons j when the spring has been 



M 



