244 



Mr. E. G. Young. 



The results obtained as shown in Table VII indicate very small changes. 

 It is well to point out that the amount of albumin undergoing change is very 

 small relative to the amount present. This I have repeatedly shown by heat 

 coagulation of the remaining solution at its isoelectric point. The arc light 

 was used in this experiment and the solutions exposed in glass spectroscope 

 boxes. 



Table VII. — Effect of Illumination on Viscosity and Surface Tension. 



Exposure time. 



Viscosity. 



1, x 10 3 . 



Surface tension. 



7- 



hours. 



seconds. 





drops. 









19 -80 



11 75 



39-00 



69 -74 



1 -5 



20 -60 



12 -23 



39-10 



69 56 



3-0 



20 -80 



12-34 



39-60 



68 -70 



4-5 



21-00 



12-47 



39-70 



68 -52 



Concentration of ovalbumin, 2 "10 per cent. 



There is thus a slight decrease in surface tension (y) and a slight increase 

 in viscosity (77), but the changes are so slight that as a means of following 

 the rate of reaction they are unsuitable. It is, however, significant that 

 such changes occur, indicating as they do underlying chemical changes while 

 the denatured particles remain dispersed. The work is being repeated with 

 serum albumin solutions. 



Experiment 4. — The Effect of various Substances on the Rate of Denaturation. 



For the following tests a solution of serum albumin, twice recrystallised, 

 was used. It still contained the mother liquor adherent to the crystals, so 

 that there was an appreciable quantity of (NH 4 ) 2 S04 present (about 1 per 

 cent.). This solution was quickly affected by sunlight, depositing a massive 

 precipitate in an hour if the sunlight were intense. It was denatured by the 

 arc light on 2 hours' exposure. The precipitate was found to be soluble in 

 excess water, acid or alkali. The solution in water or acid could only be 

 brought about with precipitates formed quickly and freshly deposited. This 

 observation is comparable with that of Michaelis and Eona (10) on heat 

 coagulation of serum albumin. If the precipitate forms slowly, its solubility 

 in both acid and water is lost. I am not able to say whether the resolution 

 is an indication of a truly reversible reaction, or whether it merely indicates 

 on the part of the colloid the ability to reassume a charge and disperse itself, 

 as is the case of pure gelatin, about its isoelectric point. Michaelis and Eona 

 state that in the case of heat coagulation it is a true reversion, but adduce 

 no evidence for their belief. In this connection it is interesting to recall the 



