INSOLUBLE CARBOHYDRATES OR MARC. ' 78 



Another paper by Fremy rt appeared in 184S. The facts contained 

 in the previous paper are retold, and new ones are given. The article 

 ignores the work of every other chemist working in the field, and 

 appears thirty-five years later, practically without change, in the 

 Encyclopedic Chimique. 



Neubauer* reported concerning arabin, precipitated by alcohol from 

 gum arabic solution (found by Scheibler to be identical with metapec- 

 tic acid). 



Fremy c obtained metapectic acid by boiling beet marc with milk of 

 lime. 



Stude d published work which was largely confirmatory of work 

 already done by others. The existence of pectose was denied, the 

 author believing that the pectin bodies in tissues existed as calcium n 

 pectate. No data of any kind are given in the paper. 



Scheibler * published two papers of much interest in which the for- 

 mation of sugar from pectin is described. Metapectic acid was pre- 

 pared from beet marc, and this by acid hydrolysis yielded a crystal- 

 lizable sugar which he called arabinose. This was followed in IHTS-^' 

 by a report of further work dealing with arabinose and metapectic 

 acid. The sugar was the same whether prepared from beet marc or 

 from gum arabic. The method of preparing metapectic acid used by 

 him was as follows: 



Beet pulp was repeatedly washed and macerated in cold 85 per cent 

 alcohol. The pressed-out residue was thrown into boiling water, 

 alcohol boiled out, potassium hydroxid added to a strong alkaline 

 reaction, and the solution heated for a long time on a water bath. 

 The product was then filtered, saturated with carbon dioxid, concen- 

 trated by evaporation, filtered, and the filtrate acidulated with acetic 

 or hydrochloric acid. The pectic acid was then precipitated with 

 alcohol and the crude product purified by repeated solution in water and 

 precipitation with alcohol. Finally, the concentrated aqueous solu- 

 tion was poured into a small high cylinder* a little alcohol was added, 

 and the mixture was allowed to stand several weeks. During this 

 time there was formed a precipitate which carries nearly all the ash, 

 and the filtrate yielded arabic acid of fine quality. 



Girard-' 7 determined the pectin in gum tragacanth. 



Kirchner and Tollens 7 ' hydrolyzed quince gum by boiling with 1.15 

 per cent of sulphuric acid for varying periods of time. In one exper- 



Ann. chim. phys., 1848, [3] 24: 5;. J. f. prak. Chem., 1848, 4-5: 385; Ann. Chem. 

 (Liebig), 1848, 07: 257. 



& J. prak. Chem., 1854, 62: 193. 



cCompt. rend., 1859, 40: 561. 



^Ann. Chem. (Liebig), 1864, 131: 241. 



*Ber. d. chem. Ges., 1868, 1: 58, 108. 



/Ibid., 1873, : 612. 



<7lbid., 1875, 8: 340. 



A Ann. Chem. (Liebig), 1875, 175:" 205. 



