102 Experiments on a Substance ji'hkh possesses 



ounces. I am convinced that much more might have been 

 obtained from the residuum of the peat, had I thouglu proper 

 to have repeated the operation 5 and I am also certain tliat 

 less nitric acid would have been sufficient, had the process 

 been conducted in close vessels, and with other oeconomical 

 precautions, which at that time were, tor the sake ot" expe- 

 dition and convenience, omitted. 



§ VI. 



It has been generally stated, even by modern chemist?, 

 tl)at the acids act but little, it' at all, upon resinous sub- 

 stances. 



The contrary has, however, been proved, not only in the 

 three papers upon the present subject, but also in some others 

 which I have formerly had the honour to lay beibre this 

 learned society. 



In my experiments on lac, printed in the Phil. Trans, 

 for 1804, p. iiOS, I have particularly endeavoured to show 

 how powerfullv the acetic acid acts upon resin, gluten, and 

 some other substances ; so that it may justly be regarded 

 as a valuable agent in tiie chemical analvsis of vegetable 

 bodies. In this point oi view, it is as a solvent to be the 

 more highly appreciated, because it appears to dissolve the 

 resins, &,c. witliout aflecting their respective qualities; and 

 thus, by proper prccipitants, these substances may be sepa- 

 rated from it pure and unaltered. 



I am induced, therefore, to consider acetic acid to be the 

 true acid solvent of the resinous substances, as it dissolves 

 them speedilv, without producing anv apparent subsequent 

 change in their natural properties. 



Sulphuric acid, also, almost immediately dissolves the 

 resins, balsan)s, 8cC. and forms transparent brown or some- 

 times crimson solutions, the latter colour being most com- 

 monly characteristic of the bal^auis. 



These solutions, however, are ditlerent from those made 

 in the acetic acid, bv mn being permaneul; for, from the 

 monient when the solu:;()n is completed, pro2.rcrisivc altera- 

 tions appear to be produced in the body which is dissolved ; 



thus 



