135 



rliombic prisms of glass lustre, is permanent at the air, neutral, 

 has a refreshing bitter taste, dissolves readily in water, decomposes 

 in aqueous solutions and in the presence of myrosin (emulsin of 

 the white mustard) into KO + 2 SO3 + HO, C« H5 NS2 and 

 into C12 H12 Oio, the latter body being identical with grape-sugar. 

 From the Älyronate of potash the Myronic acid is obtained by 

 removing the potash with tartaric acid, or by converting the 

 ])otash-salt into the baryta compound, and decomposing the 

 latter with sulphuric acid. — The Myronic acid forms a colourless 

 and inodorous syrup-like licpiid, has a bitter taste and an acid 

 reaction; decomposes readily with heat; dissolves readily in 

 water and in alcohol, scarcely in ether, forms with potasli, soda, 

 ammonia and baryta crystallisable, with lime, oxyd of lead and 

 oxyd of silver amorphous salts of bitter taste. 



Myrosin. The albuminous or emulsin-like constituent of the 

 black and white mustard seeds, Brassica alba and B. nigra, and 

 which gives rise to the formation of volatile mustard oil from the 

 myronate of potash, contained in black mustard seeds, and l)y the 

 concurrence of watei*. From the black mustard it cannot be 

 obtained, as it is instantly decomposed through the myronate of 

 potash when brought into contact with water. From the \\'hite mus- 

 tard seeds it is obtained by treating with cold water; the filtered 

 liquid is evaporated to the consistence of syi-up at a tem^terature 

 not exceeding 40° and mixed with alcohol; the Myrosin, precijji- 

 tated thereby, is redissolved in water, and the solution brought to 

 dryness with a gentle heat. — It is in physical properties very 

 similar to emulsin of almonds; yields with water a slimy solution 

 which coagulates at 60°, and likewise readily through alcohol and 

 acids. It has not been possible as yet to separate it from 

 albumin. 



[According to Will and Koerner, Myronate of potash (Sinigrin)r 

 when dissolved in water and brouglit into contact with myrosin, 

 splits into Sulphocyanide of Allyl (mustard oil), Bisulphate of 

 potash, and grape-sugar.] 



Ill5TOXOCari)ill=C4s II35 Oc. Peculiar, crystalline matter of the 

 white balsam of Peru, the latter being obtained by pressing the 

 inner parts of the fruit and the seeds of Myroxylon Pereirse. 

 Digest the balsam with alcohol of moderate strength, and leave 

 the clear liquid to evaporate; the crystals which have formed are 

 purified by animal charcoal and by recrystallising. — The crystals 

 are coloui'less, inodorous, and tasteless, hard, glossy, flat, thin, 

 moi'e than one inch long, insoluble in water, soluble in alcohol 

 and in ether, neutral, fusible at 115°, and mostly decomposing 

 in higher temperatui'es. Acids and alkalies have scarcely any 

 effect; nitric acid converts it slowly into oxalic acid and an amor- 

 phous resin. 



