)60 Experiments and Remarks on a Substance 



described with nitric acid, the quantity obtained of the tan* 

 ning substance was much less than when an equal quantity 

 of coal was employed, or even when these bodies had been 

 previously converted into coal in the humid way by sulphuric 

 acid. 



The cause of this seems to be, that a number of other 

 products are simultaneously formed, all of which require 

 more or less of carbon as a constituent ingredient, so that, 

 in consequence of the affinities which prevail under the 

 existing circumstances, some bodies by treatment with 

 nitric acid afford but little, and others none, of the tanning 

 substance. 



The greatest proportion of this substance was yi^'lded by 

 indigo, common resin, and stick lac. 



The quantity obtained from asa fcetida and gum ammoniac 

 \ras less. 



Benzoin, balsam of Tolu, balsam of Peru, and dragon's 

 blood, were inferior to the former in this respect ; so that 

 the development, or rather production of benzoic acid *, ap- 

 peared 



* The expression " production of benzoic acid" may appear objectionable, 

 and I shall therefore take this opportunity so observe, that I much suspect 

 the present established opinion respecting the balsams and benzoic acid to be 

 erroneous : for the balsams are defined as bodies composed of resin and ben- 

 zoic acid; consequently the latter, when obta'ned in a separata state, is consi- 

 dered as an orlgiiial ingredient or educt. 



I am, however, inclined to a contrary opinion ; for I consider the balsam* 

 as pecuhar substances, which, although nearly approaching to the nature of 

 resins, are nevertheless different in respect to the original combination of 

 their elementary principles; which combination, however, is with much faci- 

 Uty modified by various causes, and especially by a certain increase of tem- 

 perature, so that a new arrangement of the elementary principles takes place,, 

 part being formed into resin, and part into benzoic acid. 



Many facts appear more or less to support this opinion ; for whether ben- 

 zoic acid is obtained by simple sublimation, or by merely digesting benzoin 

 in boiling water, according to Geoffroy's method, or by the addition of lime, 

 as recommended by Scbcele, or by employing alkalis in a similar manner, 

 nothing positive can be inferred from any of these operations to prove that 

 benzoic acid is obtained as an educt, but rather the contrary, when we re- 

 flect on the-affinities which are most likely to prevail under the circumstances 

 of the different processes, and on the variable proportions of the benzoic 

 acid ; and although benzoic acid has been discovered in the urine of infants, 

 in that of mnny adults, and coiistandy in that of graminivorous quadrupeds, 



»uch 



