v ALBUMOSES AND PEPTONES 175 



Ferrocyanic acid, used generally in the form of acetic acid + 

 potassium ferrocyanide, precipitates all albumoses, but the presence of 

 peptone may interfere with the reaction. On heating, the precipitate 

 disappears, while it reappears on cooling. Nitric acid precipitates the 

 primary albumoses even in the absence of salts, the deutero-albumoses 

 only in the presence of sodium chloride, and the lowest members of 

 the deutero-albumoses only if the solution be saturated with salt. The 

 precipitate is soluble in an excess of nitric acid, especially on heating, 

 but it returns on cooling. This last reaction Kiihne held to be 

 characteristic of albumoses, but it is also given by histones (see under 

 Histone). 



Albumoses are completely precipitated by the following alkaloidal 

 reagents: Phosphotungstic-, phosphomolybdic-, picric-, tannic-, tri- 

 chlor-acetic-, and metaphosphoric acids. The tannic acid precipitate of 

 prot-albumose is, however, soluble in an excess of the acid. Some of 

 the precipitates dissolve on heating and re-form on cooling, while 

 others are permanent when heated. Albumoses are also precipitated 

 by bin-iodide of mercury dissolved in potassium iodide, bismuth iodide 

 dissolved in potassium iodide and potassium iodide + hydrochloric 

 acid, but the precipitates of the deutero-albumoses are partly soluble 

 in an excess of hydrochloric acid. Bang l has further found amongst 

 .the albumoses certain substances which must be preponderatingly 

 basic in their nature, because they are precipitated by alkaloidal re- 

 agents even if the reaction be neutral, and also by alkalies. As 

 ' acro-albumose,' Kiihne 2 and Folin 3 have described an acid albumose 

 which is precipitable by acetic acid ; it occurs occasionally in Witte's 

 peptone, and belongs, if judged by its solubility, to the primary 

 albumoses. Albumoses are laevorotatory, but so far no determinations 

 have been made with chemically pure preparations. 



The primary albumoses, but not the deutero-albumoses, give, 

 according to Kossel, 4 precipitates with protamins and histones as do 

 the natural albumins. Kutscher, 5 reversely, obtained precipitates 

 when sodium salts of the acid albumins globulin, myosin, syntonin, 

 etc. were allowed to drop into deutero- albumose solution. He 

 explains this phenomenon by assuming the formation of the slightly 

 soluble globulinates of deutero-albumose, but it is possible that the 

 deutero -albumose withdraws the sodium from the normally very 



1 J. Bang, Zeitschr. f. physiol. Chem. 27. 463 (1899). 



2 W. Kiihne, Zeitschr. f. Biol. 30. 221 (1894). 



3 0. Folin, Zeitschr. f. physiol. Chem. 25. 152 (1898). 



4 A. Kossel, Deutsche tried. Wochenschr. 1894, p. 146 ; Zeitschr. /. physiol. Chem. 

 22. 176 (1896). 



5 F. Kutscher, ibid. 23. 115 (1897). 



