vin THE DENATURALISATION OF ALBUMINS 341 



on drying casein at 1 00, observed that it is disintegrated into phosphoric 

 acid and at least two albuminous substances which differed from one 

 another and from the original casein. It is uncertain as to whether 

 this great susceptibility is due to want of purity or due to the 

 peculiar constitution of casein. 



Alcohol. Salt-free albumin is precipitated by alcohol only with 

 difficulty ; and such alcohol-precipitated albumin is at first still soluble, 

 but on the addition of a trace of salt the precipitate becomes very 

 abundant, and this precipitate quickly loses its colloidal nature 

 (Aronstein, 1 Harnack, 2 Alexander Schmidt, 3 Kiihne, 4 v. Furth, 5 and 

 Spiro 6 ). According to Kiihne and Chittenden, 7 albumoses and 

 peptones are also precipitated much more completely if salts are 

 present, but in this case a possible error may have crept in owing to 

 the presence of alcohol-soluble acid-albumins. 



Lilienfeld 8 in 1893 observed that albumin fixed in absolute 

 alcohol has no affinity for either acid or basic dyes. Mathews 9 has 

 also pointed out that egg-white, coagulated by heat or by alcohol, does 

 not stain in neutral solutions of either colour-acids or colour-bases. 

 " It is true it will imbibe a certain amount of colour and will appear 

 stained, but this colour is easily and quickly removed by washing in 

 water." . . . "A most striking contrast is shown by two pieces of 

 coagulated albumin, one of which has been immersed in a neutral, the 

 other in an acid solution of acid fuchsin. After washing, the former 

 will be found to be colourless, the latter a brilliant red." . . . "If two 

 pieces of (alcohol-) coagulated egg-albumin be brought, the one into 

 slightly acid and the other into alkaline solutions of thionin, the stain 

 poured off after a few seconds, and the albumin washed in water, the 

 piece that has been in the alkaline solution will be an intense purple, 

 the other barely tinged with colour." ..." These reactions clearly 

 indicate that the staining of coagulated albumin depends on chemical 

 combinations similar in all respects to those which the albumoses enter 

 into with the same stains. In neutral solution, neutral coagulated 

 albumin combines neither with acid nor with basic stains ; in alkaline 

 solutions it combines only with the basic ; in acid solutions, only with 



1 B. Aronstein, Pftiiger's Arch. f. d. ges. Physiol. 8. 75 (1874). 



2 E. Harnack, Ber. d. deutsch. chem. Ges. 22. VI. 3046 (1889). 



:! Alexander Schmidt, Zur Blutlehre, Leipzig, 1892 ; Weitere Beitrdge zur Blutlehre 

 Wiesbaden, 1895. 4 W. Kiihne, Zeitschr. f. Biol 29. 1 (1892). 



5 0. v. Furth, Arch./, experiment. Pathol. u. Pharmakol. 36. 231 (1895). 



6 K. Spiro, Hofmeisters Beitrage, 4. 300 (1903). 



7 W. Kiihne and R. H. Chittenden, Zeitschr. f. Biol. 19. 188 (1883). 



8 Lilieufeld, Arch. f. Anat. u. Physiol. 1893, p. 391, and in Zeitschr. f. physiol. 

 Chem. 18. 473 (1894). 9 A. Mathews, Amer. Journ. of Physiol. 1. 445 (1898). 



