vin OTHER PHYSICAL PROPERTIES OF ALBUMINS 335 



albumins of forming permanent emulsions with finely divided fat- 

 droplets : on precipitating the casein the whole of the emulsified fat 

 also separates out. An explanation of the formation of the haptogen- 

 membranes has been given by Jamison and Hertz, who worked under 

 Ramsden. 1 They showed that the film or skin on milk is not peculiar 

 to caseinogen or lactalbumin, as similar films are produced on warming 

 any albuminous solution containing emulsified fat or paraffin. In the 

 case of non-coagulable albumins at any temperature, and in the case of 

 heat-coagulable albumins at a temperature beneath that of heat- 

 coagulation, the film is probably formed of unchanged dry albumin. 

 If a coagulable albumin is coagulated by heat, then the film is com- 

 posed, at any rate partly, of coagulated albumin. Drying is therefore 

 one essential condition for the formation of a film, which latter, 

 in addition to dried albumin, contains also, entangled in the film, 

 globules of fat or of paraffin. 



7. Power of clarifying Solutions 



The very opposite of the phenomena described in the previous 

 paragraph is the following one : When albuminous substances are 

 either precipitated, or when they otherwise come into contact with 

 substances which are in solution along with themselves, they carry these 

 other substances down with them by enclosing them, or condensing them 

 on their own surfaces by surface attraction. To this special power 

 used to be attributed the precipitation of ferments, but Jacoby 2 has 

 shown that ferments, as regards precipitation, are subject to the same 

 conditions as are albumins, and that surface attraction only comes into 

 play when ferments are precipitated on fibrin. The dye-stuff's, salts, 

 etc., which albumin-crystals imbibe, according to Wichmann, 3 "like a 

 sponge," are certainly held by chemical forces (Mann) ; 4 and the same 

 holds good for the ash constituents (Kossel 5 and Harnack 6 ), which, so 

 far, it has been impossible to completely remove from albumin. Even 

 the most "ash-free" albumin of Hofmeister 7 contained traces of 

 inorganic constituents, and it is nothing uncommon for pure albumin 

 to contain O'5-l per cent of ash. Compare also the views of Ramsden 

 on mechanical conglutination, p. 274. 



1 K. Jamison and A." F. Hertz, Journal of Physiol. 27. 26 (1901). 



2 M. Jacoby, Zeitschr. f. physiol. Ghem. 30. 135 (1900) ; Arch, fur experiment. 

 Path. u. Pharmak. 46. 28 (1901). 



3 A. Wichmann, Zeitschr. f. physiol. Ghem. 27. 95 (1899). 



4 Mann, Physiological Histology, 1902, pp. 289, etc. 



5 A. Kossel, Zeitschr. f. physiol. ^hem. 3. 58 (1879). 



6 E. Harnack, ibid. 19. 299 (1894). 



7 F. Hofmeister, ibid. 16. 187 (1891). 



