Power of Crystalline Ovalbumin and Serum Albumin. 19 



Table III. 



Crystallisation. 



Second. 



Third. 



Fourth. 



Fifth. 



Average. 



Concentration (per cent.) — 



(1) (NH 4 ) 2 S0 4 method ... 



(2) Buffer method 



Ph 



M» 



M« 



9 -87 

 9-89 

 5-4 

 -11 -96° 

 -14 -66 

 - 30 -26 

 -37 09 



10 '95 

 10 -96 

 5 4 

 -13 22° 

 -16-12 

 -30 -17 

 -36-79 



15 -43 

 15 -42 

 5-3 

 -18-52° 

 -22 -58 

 -30 -02 

 -36 -61 



12 -64 

 12 -66 



5-3 

 -15 -22° 

 -18 -57 

 -30-10 

 -36-70 



-30 -14 3 

 -36 -80 



salt from that obtained previously. This possibility, more fully discussed iu 

 the notes on the method of preparation, suggested the desirability of 

 studying the variation of the specific rotation in relation to the hydrogen 

 ion concentration of the solution. 



The Influence ofYn on Rotatory Power. 



The condition in which the protein molecule is isoelectric to the electric 

 current has such a profound influence upon its physical properties that it 

 was thought that a study of the relation of this condition to the optical 

 rotation might yield an explanation of the divergent values recorded in the 

 literature. For the purpose of experimentation, crystalline material, which 

 had been crystallised four to six times, was used. The last precipitate of 

 crystals was centrifuged at high speed from its mother liquor and redissolved 

 in distilled water. The resulting solution thus contained a small amount of 

 (ISTEU^SO,!. The changes in hydrogen ion concentration of the solution were 

 followed by means of various indicators, using the standard buffer mixtures 

 devised by Clark and Lubs (1917). A series of reagents was prepared by 

 the use of material which had been purified to the standard required and 

 dissolved in water which had been twice distilled in glass, firstly from 

 KMn0 4 and H 2 S0 4 , and secondly from Ba(OH) 2 . All test-tubes employed 

 were of uniform diameter, of clear, colourless glass, and had been steeped in 

 dichromate cleaning mixture for 24 hours, and then steamed in superheated 

 steam for 1 hour. 



After some experimentation, the following series of indicators was selected 

 as most suitable for use in solutions containing both protein and salt : — 

 P H range. Indicator. 



1-2— 2-8 

 44— 6-0 



6- 4— 7-8 



7- 8— 8-4 



8- 4—10-0 



Thymol blue. 

 Methyl red. 

 Neutral red. 

 Phenol red. 

 Phenolphthalein. 



c 2 



