206 ALKALOIDS. 



Choline and amanitine are also tolerably strongly alkaline. The 

 double salt of platinum and choline is precipitated by alcohol 

 from aqueous solution (contains 31-75 to 33-27 per cent. Pt.); the 

 gold double salt is sparingly soluble in cold Avater, more freely in 

 boiling (contains 44-25 to 44-9 per cent. Au.). The gold and 

 platinum double salts of betaine are freely soluble in water, and 

 especially so in alcohol, but more sparingly in ether. 



§ 191. Asparagine. — This substance requires 40 parts of cold 

 and 4 of warm water for solution, and is insoluble in absolute 

 alcohol and in ether. It crystallizes in colourless rhombic prisms. 

 Boiling Avith hydrochloric acid resolves it into aspartic acid and 

 ammonia, a reaction upon which Sachsse^ based the following 

 method for the quantitative estimation: — 10 grams of the poAvdered 

 substance are boiled for a quarter of an hour with 200 cc. of a 

 mixture of equal volumes of alcohol and water, in a flask pro- 

 vided with an upright condenser ; 5 cc. of a cold saturated 

 alcoholic solution of mercuric chloride are diluted with 5 cc. of 

 water, and added to the mixture whilst still hot, the whole thrown 

 on a filter, and washed first "with hot 50 per cent, spirit, and 

 finally Avith cold water. The filtrate and washings are evaporated 

 to dryness, the residue redissolved in the smallest possible quan- 

 tity of water (not more than 50 cc), from which solution the 

 mercury is precipitated with sulphuretted hydrogen. The sulphide 

 of mercury is filtered off" and washed with hot Avater until filtrate 

 and Avashings measure 110 to 120 cc. This liquid is then mixed 

 with 10 cc. of hydrochloric acid and boiled for an hour (Avith 

 upright condenser), by Avhich the asparagine is decomposed into 

 ammonia and aspartic acid ; it is then cooled in an atmosphere 

 free from ammonia, and made slightly alkaline Avith pure potash. 

 The ammonia produced may be estimated gasometrically by 

 Knop's method ; 14 parts by weight of nitrogen indicate 132 of 

 anhydrous asparagine. For asparagine, see also §§ 97, 210. 



The microscopical detection of asparagine may be effected by 

 taking advantage of its insolubility in absolute alcohol. Crystal- 

 line deposits of that substance are usually formed Avhen fresh 

 sections of plants containing it are placed in alcohol. After being 

 dried they are insoluble in a cold saturated aqueous solution of 



Wochenschr. 1875 (Amer. Journ. Pharm. 209, 1875). Compare also Annal. 

 d. Chem. und Pharm. (Suppl.) ii. 383, iii. 245, 1864. 



1 Journ. f. pract. Chem. vi. 118, 1873 (Journ. Chem. Soc. xxvi. 652). 



