208 CYANOGEN COMPOUNDS. 



and potassium salts of gummic acid. The latter is 

 obtained from this pure,&quot; by precipitating its solution, 

 containing hydrochloric acid, with alcohol. A white, 

 amorphous, easily soluble mass separates, which is 

 vitreous after being dried at 100 ; has the composition 

 QejjioQs _j_ iH 2 0, and does not lose its water under 120- 

 130. 



A solution of gum rotates the plane of polarization 

 to the left. &quot;When boiled for a long time with dilute sul 

 phuric acid, it is converted into sugar (grape-sugar?). 

 Nitric acid oxidizes it, forming mucic, saccharic, tar- 

 taric, and oxalic acids. 



19. Vegetable Mucus (Bassoriri), C 6 H 10 5 . Is very 

 widely distributed in the vegetable kingdom, as a solid 

 mass deposited on the cell-walls, or in a condition simi 

 lar to solution as a glairy mass. The following sub 

 stances are richly supplied with vegetable mucus: 

 Tragacanth (the spontaneously exuded sap of Astragalus 

 varieties) ; gum of Bassora, cherry-tree gum, plum-tree 

 gum, salep (from different Orchis varieties), caragheen 

 moss ; further, linseed, Semen psyllii, quince seeds, the 

 root of Althcea officinalis, and Symphytum officinale, etc. 

 Colorless or yellowish, translucent thick mass, inodorous 

 and tasteless. Swells up with water, forming an 

 exceedingly voluminous mucus, without dissolving. 

 Yields, with nitric acid, the same products as gum. 



NINTH GROUP. 

 CYANOGEN COMPOUNDS. 



Cyanoen. 



C 2 N 2 



Formation. Cyanogen compounds are produced from 

 carbon and nitrogen, which unite at a high temperature 

 in the presence of metals ; by the distillation of a great 



