\70 Dr. Schunck on the Action of 



lead a pinkish-white precipitate, which seemed, however, to con- 

 sist principally of carbonate of lead, as on treating a small quan- 

 tity of it with nitric acid it dissolved with effervescence. This 

 precipitate being decomposed with sulphuretted hydrogen, and 

 the liquid being treated in exactly the same manner as that 

 resulting from the crude succinate of lead in the other experi- 

 ments, a syrup was obtained, which yielded, however, not a trace 

 of crystalline sublimate when heated in a tube. The formation 

 of the succinic acid, as well as of the alcohol and the gases, is 

 therefore clearly due to the decomposition of the sugar induced 

 by the action of the ferment. 



Since madder itself contains a considerable quantity of sugar 

 ready formed, and an additional quantity is always produced by 

 the decomposition of rubian, it was natural to suppose that 

 watery extracts of madder might be found to contain succinic 

 acid. For the purpose of ascertaining whether this was the case, 

 I took some of the brown syrup which had been obtained by 

 extracting French madder with boiling water, precipitating the 

 colouring matter, &c. with oxalic acid, neutralizing the excess of 

 acid with carbonate of lime, and evaporating the filtered liquid, 

 which had been standing in the state of syrup for several years. 

 A quantity of this syrup having been mixed with water, I added 

 to it acetate of lead, which produced a dark brown precipitate. 

 This preeipitatQ being treated in precisely the same manner as 

 the lead precipitate thrown down by sugar of lead from the solu- 

 tions of sugar fermented with erythrozym, yielded a small quan- 

 tity of a white crystallized acid, which, when heated in a tube, was 

 completely volatilized, giving a beautiful crystalline sublimate, 

 exactly resembling that produced by succinic acid. It is there- 

 fore very probable that succinic acid is either contained as such in 

 madder, or is formed during or after the process of extraction by 

 the action of the ferment on the sugar contained in the extract. 



A few years ago the only known sources of succinic acid were 

 amber, turpentine, and some species of brown coal and retin- 

 asphalt. Latterly it has been discovered in several plants, such 

 as the Lactuca saliva and virosa*, and the Artemisia Absinthiumf, 

 and it has been detected in the liquid extracted from cysts con- 

 taining Echinococci from the human liver J. It has moreover 

 been produced artificially by the action of nitric acid on different 

 kinds of fat and fatty acids, such as tallow, wax, spermaceti, and 

 stearic and margaric acids § -, and its formation during the fer- 



* Kohnke, Brandes Archiv, 2 aer. vol. xxxix. p. 163. 

 t Zwenger, Annalen der Pharmacie, vol. xlviii. p. 122. 

 j Heintz, Poggendorflfs Annalen, vol. Ixxx. p 114. 

 § Bromeis, Sthamer, Radcliffe, Ronalds, Annalen der Pharmacie,\o\. xxxv. 

 p. 90 J vol. xliu. pp. 346, 349, 356. 



