208 VEGETABLE MUCILAGE. 



It is characterized by crystallizing in spharo-crystals, by its be^ 

 haviour to water and alcohol (dissolves in 27 parts of cold, and 

 easily in warm water, in 1040 of cold 96 per cent, spirit, and 

 800 of boiling 98 per cent.), by its power of dissolving oxide, of 

 copper, and by yielding leucic acid when acted upon by nitrous 

 acid. 



I have already directed attention to the identity of the chem- 

 podiTie obtained from decomposing yeast with leucine.'- G*nip 

 Besanez has made the same assertions of the chenopodine from 

 Chenopodium album. 



Tyrosine, as well as leucine, has lately been detected in plants, 

 especially in germinating seeds. ^ Aqueous extracts of the material 

 imder examination are concentrated, precipitated with alcohol^" 

 iiltered, freed from aicoholby distillation, evaporated to .a eyrup, 

 and allowed to stand, when the tyrosine separates out in groups 

 of warty crystals. By recrystallization from ammoniacal alcohol 

 it may be obtained in acicular crystals. Solutions of the latter, 

 develop a rose-colour with mercuric nitrate' and a little nitrous 

 acid. Warmed to 50° with concentrated sulphuric acid (half-hour), 

 and saturated .with carbonate of barium, it yields a mass which 

 assumes a fine violet with ferric cMoride. 



BatcmMn agrees with tyrosine in most of its reactions, especially 

 the two just described. It is almost insoluble ia cold water, 

 alcohol and ether, sparingly soluble in boiling watier, but freely in 

 ammonia. Suspended in water, and then warmed with a little 

 nitric flcid, it dissolves, passing, as it doep so, from rose to ruby- 

 red and bluie, turning finally green with red fluorescence. ^ 



VEGETABLE MXTCILAGE. 



§ 193. Vegetable MucUage, Pectin, efc.— The substances desig- 

 nated by these names are a source of much inconvenience to the 

 analyst, due probably to their occurring in various modifications 



1 Compare Bergman, ' Das putride Gift,' Dorpat Glaser. See also Eeinsch, 

 N. Jahrb. f. Pharm. xxvii. 123, 1867. 



2 Compare Scbufee , and Barbieri, Ber. d. d. chem. Ges. x. 199, xi. 710 

 (Journ. Chem. Soo.xxiiv. 663). 



' It is notorious that ratanhin does not occur in rhatany-root, and that its 

 presence in certain samples of commercial extract of rhatanj is due to adultera- 

 tion. Compare also Exeitmair, Jahresb. f. Pharm. 136, 1874 (Tear-book 

 Pharm. 90, 187S). GintI believes ratanhin to be identical with angelin from 

 Ferreira spectabilis (Zeitschr. d. osterr, Apoth. Ver. 32, 1869). 



