OVOMUCOID. 603 



HALDEN and PREGL l on the hydrolysis of ovalbumin do not show any- 

 thing of special interest. 



As in the past certain doubts have existed as to the purity and chem- 

 ical unity of the ovalbumins or also of the crystalline ovalbumin, so now 

 this doubt has become still stronger since ovalbumin has been prepared 

 partly free from phosphorus and partly with a variable phosphorus 

 content of 0.1-3.06 per cent (KAAS, WILLCOCK and HARDY 2 ). 



In preparing crystalline ovalbumin, mix, according to HOFMEISTER, 

 the beaten white of egg free from foam with an equal volume of a saturated 

 ammonium-sulphate solution, filter off the globulin, and allow the nitrate 

 to slowly evaporate in thin layers at the temperature of the room. After 

 a time the masses which separate out are dissolved in water, treated 

 with ammonium sulphate-solution until they begin to get cloudy, and 

 allowed to stand. After repeated recrystallization the mass is either 

 treated with alcohol, which makes the crystals insoluble, or they are 

 dissolved in water and purified by dialysis. From these solutions the 

 proteid does not crystallize again on spontaneous evaporation. (See also 

 page 602, foot-note 2, for the HOPKINS and PINKUS method.) WILL- 

 COCK 3 has recently found that magnesium sulphate can also be used in 

 the crystallization of ovalbumin. 



Conalbumin can be removed from the filtrate, after the complete 

 crystallization of the ovalbumin, by removing the sulphate by means of 

 dialysis and coagulating by heat. 



GAUTIER 4 found a fibrinogen-like substance in the white of the egg, which 

 was changed into a fibrin-like body by the action of a ferment. 



Ovomucoid. This substance, first observed by NEUMEISTER and 

 considered by him as a pseudopeptone and then later studied by SALKOW- 

 SKI, is, according to C. TH. MoRNER, 5 a mucoid with 12.65 per cent nitro- 

 gen and 2.20 per cent sulphur. Ovomucoid exists in hen's eggs to the 

 extent of about 10 per cent of the total solids. 



A solution of ovomucoid is not precipitated by mineral acids nor by 

 organic acids, with the exception of phosphotungstic acid and tannic 

 acid. It is not precipitated by metallic salts, but basic lead acetate and 

 ammonia render it insoluble. Ovomucoid is thrown down by alcohol, 

 but sodium chloride, sodium sulphate, and magnesium sulphate give 

 no precipitates either at the ordinary temperature or when the salts are 

 added to saturation at 30 C. Its solutions are nolj precipitated by an 



1 Zeitschr. f. physiol. Chem., 46. 



2 Kaas, Monatsh. f. Chem.. 27; Willcock and Hardy, cited from Chem. Centralbl., 

 1907, 2, 821. 



3 Journ. of Physiol., 37. 



4 Compt. rend., 135. 



5 R. Neumeister, Zeitschr. f. Biologic, 27; Salkowski, Centralbl. f. d. med. Wis- 

 sensch., 1893, 513 and 706; C. Morner, Zeitschr. f. physiol. Chem., 18. See also Lang- 

 stein, Hofmeister'p Beitrage, 3 (literature). 



