166 GLUCOSIDES OTHER THAN TANNINS. 



by emulsin) into volatile oil of mustard (sulphocyanide of allyl, 

 29), characterized by its extreme pungency, glucose and bisul- 

 phate of potassium. A quantitative estimation might possibly be 

 made by freeing the finely-powdered seeds from oil, exhausting 

 with warm 85 per cent, spirit, and digesting the tincture for 

 some time with carbonate of barium. From the filtrate the 

 alcohol might be recovered by distillation, the residue dissolved 

 in water, and digested with myrosin at a temperature of about 40, 

 the barium being finally precipitated as sulphate by the addition 

 of hydrochloric and sulphuric acid. One molecule of sulphate of 

 barium indicates 6ne of myronic acid. 1 



White mustard contains no myronic acid, but in its stead 

 another glucoside, to which the name of sinalbin has been given. 

 Like myronic acid, it dissolves in boiling 85 per cent, spirit, 

 separating out again to a great extent on cooling. It is crystal- 

 line, insoluble in ether and bisulphide of carbon; sparingly 

 soluble in cold, freely in hot alcohol, and in water. Alkalies 

 colour it 'yellow, nitric acid transiently blood-red. It reduces 

 alkaline copper solution, and is precipitated by mercuric chloride 

 and nitrate of silver. Warm solution of caustic soda converts it into- 

 sulphate and sulphocyanide of soda; myrosin into glucose, acid 

 sulphate of sinapine and sulphocyanate of acrinyl (C 7 H 7 0, NCS). 



Sulpliocyanate of sinapine, which also occurs in white mustard, is 

 not glucosidal, and differs from sinalbin in being more easily 

 soluble in cold alcohol, and in yielding the sulphocyanide reaction 

 directly with ferric chloride. 2 



Ericolin and menycmthin 3 are glucosides containing no nitrogen, 

 but yielding easily volatile decomposition products. The former 

 has been described in 155. Menyanthin is freely soluble in 

 warm water and in alcohol, but insoluble in ether. Cone, sul- 

 phuric acid dissolves it with the gradual production of a reddish- 

 violet colouration. Warming with dilute sulphuric acid resolves 

 it into glucose and menyanthol, the latter possessing a penetrating 

 odour. Menyanthin is precipitated by tannic acid, but not by 

 acetate of lead. 



1 Compare Will und Kiirner, Annal. d. Chem. und Pharm. cxxv. 257, I860. 

 (Am. Journ. Pharm. xxv. 323.) 



2 Compare Will und Laubenheimer, Annal. d. Chem. und Pharm. cxcix. 

 150, 1879 (Pharm. Journ. and Trans. [3], x. 918). Babo und Hirschbrunn, 

 ibid. Ixxxiv. 10, 1852. 



8 Compare Kromayer, foe. at. ; Liebelt, Jahresb. f. Pharm. 119, 1877. 



