CHAP. III.] PRECIPITATION OF BASES BY PHOSPHOTUNGSTIC ACID. 255 



through his pupils Ernst Fischer 1 , Max Siegfried 2 , T. G. Hedin 3 and 

 T. R. Kriiger 4 ,,have led to results of the deepest interest which have 

 already thrown great light on the important question of the origin of 

 a part of the urea formed in the organism. 



Pure casein was the body first investigated by Drechsel, and he sub- 

 jected it to decomposition by the method employed by Hlasiwetz and 

 Habermann, adding however to the contents of the flask metallic zinc, so 

 as to keep up a constant evolution of hydrogen, the apparatus being 

 arranged so as to exclude atmospheric oxygen. 



Employment When the decomposition of the proteids had been 



of phospho- completed, the contents of the flask were somewhat diluted 

 tungstic acid and freed from tin by the action of H 2 S. Having been 

 to precipitate evaporated to the original volume, the hot solution was 

 treated with a hot saturated solution of crystallised phos- 

 photungstic acid 5 . This reagent produces a precipitate in which all the 

 bases are contained, whilst the filtrate contains all the amido acids. 



The precipitate was then washed with water containing five per cent, 

 of sulphuric acid and an equal quantity of phosphotunsgstic acid, until all 

 traces of chlorine had disappeared ; it wasHhen suspended in boiling water 

 and decomposed by the addition of a slight excess of baryta water. The 

 fluid having been boiled, to expel ammonia, was then filtered, and from the 

 filtrate the excess of barium precipitated exactly by sulphuric acid. The 

 Itrate from the barium sulphate precipitate was then saturated with HC1 

 and concentrated on the water bath. The thick syrup thus obtained when 

 )laced over sulphuric acid gradually became converted into a crystalline 

 By treating this with spirits of wine, from the already almost 

 )lidified syrup a beautifully crystalline hydrochlorate was obtained, which 

 is found to be readily soluble in water, but insoluble in absolute alcohol, 

 proved to be the hydrochlorate of the new base lysine, CH 4 N 2 O 2 . 

 In the mother liquor the hydrochlorate of lysatinine is contained. In 

 subsequent researches the latter part of the process was somewhat modi- 

 fied. Thus the syrupy liquid containing the hydrochlorate of lysine was 

 >lved in 50 per cent, alcohol, and treated with alcoholic solution of 

 )latinum chloride. This reagent precipitated, in the first instance, some 

 >tassium platinochloride. After separation of the latter, the further 

 addition of alcohol caused the separation of a platinochloride, which after 

 being crystallised repeatedly, presented the appearance of beautiful yellow 



1 Ernst Fischer, 'Ueber neue Spaltungsproducte des Leimes,' Du Bois' Archiv. 

 pp. 265269. 



2 Dr Max Siegfried, ' Zur Kenntniss der Spaltungsproducte der Eiweisskorper,' 

 Ber. d. deutschen chemischen Gesellschaft. Vol. xxiv. p. 418, and Du Bois' Archiv, 

 1891, pp. 270273. 



3 Dr S. G. Hedin, ' Zur Kenntniss der Producte der tryptischen Verdauung des 

 Fibrins,' Du Bois' Archiv, 1891, pp. 273278. 



4 E. Drechsel und Th. R. Kriiger, ' Zur Kenntniss des Lysins,' Ber. d. deutsch. 

 chewiach. Gesellschaft. Vol. xxv. (1892), p. 2454. 



5 This reagent had been long employed as a general precipitant of vegetable bases, 

 being known as ' Scheibler's reagent ' ; it had been used by Korner (Pfliiger's Archiv, 

 Vol. n. p. 226) as a precipitant of creatinine, and had been employed by Dr Franz 

 Hofmeister for the separation of kynuric acid from the urine of dogs ; this author 

 shewed that besides creatinine, it precipitated xanthine (F. Hofmeister, 'Ueber die 

 durch Phosphorwolframsaure fallbaren Substanzen des Harns,' Zeitschr. f. phys. 

 Chem., VoL v. (1881), pp. 6774). 



