70 STUDIES ON APPLES. 



Fromberg a corroborated some of Fremy's work. Beet marc was 

 boiled with dilute sodium carbonate in order to extract the pectin as 

 the sodium salt of pectic acid, and the acid was precipitated by addi- 

 tion of excess of hydrochloric acid to the solution. On boiling a 

 solution of pectic acid made faintly alkaline, a solution of the salt of 

 metapectic acid was usually formed, from which no precipitate formed 

 on acidifying. 



Chodnew b added materially to this literature of the pectin bodies. 

 He considered that little was established in regard to their properties 

 or constitution. 



Pectin was prepared from pears, which were ground up, boiled, and 

 the juice filtered first through linen, then through paper. The bright 

 filtrate was precipitated with alcohol, and the filtrate washed with 

 alcohol and ether and squeezed out, whereby it lost its gelatinous 

 character and became like wood} T fiber (Holzfaser). This pectin was 

 soluble, easily powdered, neutral in reaction, and gave no precipitate 

 with calcium or barium chlorid, or with ammonium hydroxid. Lead 

 acetate, basic lead acetate, copper sulphate, limewater, and potassium 

 hydroxid gave the gelatinous precipitates. This pectin contained 

 from 8.5 to 8. TO per cent ash. 



Pectin from apple juice was studied in a similar way. It was also 

 high in ash, but was largely freed from ash by precipitating by 

 alcohol from an acid solution. This pectin gave the combustion 

 figures: Carbon, 43.70 and 43.79; hydrogen, 5.63 and 5.41; oxygen, 

 50.67 and 50.80; and differed from pear pectin by not dissolving clear 

 in water. Pectin is given as C^H^O^. 



. Pectic acid was studied, the author first giving a resume of previous 

 work, particularly that of Fremy. It was prepared as follows, mostly 

 from white beets: The marc was boiled with dilute potassium hydroxid 

 for a quarter to half an hour, and filtered first through cloth and then 

 through paper, the last filtration being very slow. It was considered 

 better, after filtering through cloth, to precipitate the free acid and 

 dissolve in ammonium hydroxid, which yields easily filterable solu- 

 tions. The pectic acid was precipitated by hydrochloric or nitric 

 acid washed with acidulated water, then with water containing alcohol, 

 and finally with alcohol, and pressed out by hand. Alcohol is neces- 

 sary in the wash water, for as the mineral acid diminishes in concen- 

 tration, the pectic acid begins to stop up the pores of the filter. With 

 alcohol the precipitate gradually lost its gelatinous property and 

 became like woody fiber. It was colorless and easily powdered. By 

 long drying at 120^ C. it became } T ellow-colored. It was obtained 

 nearly free from ash by repeatedly precipitating with alcohol from 

 water solution made slightly acid with nitric acid. So prepared it 

 burned without swelling, yielding 1 per cent of ash, which consisted 



Ann. Chem. (Liebig), 1843, 48 ; 56. &Ibid., 1844, 51: 355. 



