S]6 REDDENING OF LITMUS BY RESINS. 



This water has a blackish brown colour, is not precipitated 

 by acetate of lead, and does not alter the colour of litmus ; 

 but alcohol throws down a copious precipitate from it, 

 which proves, that this substaiice is composed of gum and 

 resin. 



The alcoholic tincture strongly reddens that of litmus. 

 If the resins that have most action on thecolour of litmus 

 be heated with all due precautions on u sand bath, no acid 

 sublimes. 



Treated with lime, according to Scheelc's process, no 

 calcareous benzoates are formed. 

 Various other 4, Lastly, the gum resin ammouiacum, myrrh, elerni, 

 staiiceiu ^ ' ^^^^^> galbanum, tacamahacca, resin of jalap, both pre- 

 pared by ourseli'es and that of the shops, Venice turpentine, 

 oil of turpentine, and several other resinous and gum- 

 resinous substances, afforded the same results as those ob- 

 tained from soaniniony, sandarach, and olibanum. From 

 these facts it appears still difficult to solve the question, 

 whether the reddening of litmus by resins be owii^.g ta the 

 presence of an acid in them. 

 No proof that If acids alone had the property of reddening vegetable 



tbisisocca- blues, we should not hesitate to admit their existence in 

 sioned by an . , , i_ ■ j i i 



a^,;^}^ resms, though not yet otherwise demonstrated by experi- 



ment. As to the infusion of violets not being reddened by 

 resins, this property occurs in the sublimed acid of benzoin, 

 which strongly reddens infusion of litmus, but does not 

 alter the colour of violets. Has this acid, notwithstanding 

 Benzoic acid its solubility in water, some analogy to resins ? On this 



pethripscom- r ■ ,• • ■ i -j i • • 



billed uirh ^'^ retrain from givuig a decided opinion; yet we are m- 

 some resin. dined to believe, that this Substance is a compound of a 

 vegetable acid and a small portion of resin, to which per- 

 Probnblv it is haps its solidity is owing. Finally, as all the vegetable 

 a char-icter of ;>cids are soluble in water, it is difficult to ascribe to an acid 

 renins tii , . . • r> i i ■ t^ t^. 



redden litmus, t^his property in resins ot reddening htmus. It appears 

 more proper therefore, to consider the reddening of litmus 

 as a character of resins- till fresh experiments have proved 

 the contrary. 



sl:IE^TIF^c 



