VISCOSITY OF ALBUMINOUS SOLUTIONS 19 



deducing the viscosity of water from the relative rates of flow of it and of 

 glycerine gave a value for water at 18 C. of 0-0025, which is the viscosity 

 of a 7-2 per cent, solution of Na 2 SO 4 at o C., whereas the real value for 

 water is 0-010672, or less than half that found by comparison with glycerine. 



In an experiment with water and egg-albumin the relative times of 

 flow were 118 sees, and 648 sees, at 18-5 C., which gave a value for egg- 

 albumin of 77 =0-057. Owing to the slower flow of the albumin its viscosity 

 will, however, appear to be less in comparison with water than it really is. 



The viscosity of aniline at 20 C. is 0-04467 and hence its rate of flow 

 should not differ very much from that of the egg-albumin. The average 

 time of flow of aniline was 232 sees, at i8C. and of albumin 377 sees. 

 Their densities being 1-039 and 1-042 respectively a value for r; of 0-073 is 

 obtained. Another set of experiments at 18-5 gave a value of 77 = 0-0701. 



The times of flow of various samples of egg-albumin containing 

 89 to 91 per cent, of water lay between those of solutions of sugar of 

 38 to 41 per cent, strength at i8C. Allowing for the respective densities, 

 this gave values for 77 lying between 0-06 and 0-07. It follows, therefore, 

 that the viscosity of an albuminous solution is much higher than that of 

 saline or sugar solutions of the same concentration. 



The addition of sufficient dilute saline solution to reduce the quantity 

 of albumin to 5 per cent, lowered the viscosity to 0-042, while the viscosity 

 of a solution containing 72 per cent, of water rose to 0-292 1 . Similar 

 experiments with defibrinated blood-plasma (serum-albumin and salts) 

 of the rabbit and sheep gave viscosities lying between to of those of 

 egg-albumin containing corresponding percentages of water. In solutions 

 containing 5 per cent, of serum-albumin 77 = 0-022 ; with 18 per cent, of 

 serum-albumin 77 = o-i9 2 . 



Living protoplasm may contain from 10-30 per cent, of solids, the 

 percentage probably lying near the lower limit in the endoplasm of 

 rotating cells. In all cases, however, solid floating particles are present, 

 and the influence of these upon the viscosity cannot be directly determined. 

 We have, however, weighty reasons for considering the viscosity of the 

 main bulk of the streaming protoplasm to lie within the limits 77 = 0-04, 

 and r] = 0-2 at i8C. 



1 Perfect accuracy and constancy is not claimed for these numbers, but it is useless to introduce 

 small corrections when dealing with a material whose viscosity varies according to its origin and 

 previous treatment. 



2 Few or no data on the viscosity of solutions of serum-albumin or of blood-plasma are given in 

 textbooks of animal physiology, although this is a factor of the utmost importance in determining the 

 resistance offered to the circulation of the blood, and hence the work done by the heart. In the case 

 of poikilothermic animals the viscosity of the blood-plasma will be largely influenced by the tempera- 

 ture of the surrounding medium, whereas in mammals and birds the temperature effect will be constant 

 except in cases of heat-pyrexia. The nature of the containing walls does not affect the resistance to 

 flow, so long as the lining epithelium is relatively smooth. 



C 2 



