1907.] On Globulins. 419 



conductivity of the salt used to dissolve it. The conductivity of the salt " is the same as 

 that of a similar solution in pure water/' This statement is directly contrary to my own 

 •observations. It leads me to add a few words as to the precautions which are necessary 

 in dealing with proteid solutions. 



Electrodes coated in the ordinary way with platinum black are quite useless. The 

 proteid in their immediate neighbourhood is changed very rapidly and very drastically. 

 An instance selected at random will show the magnitude of the effect. 



18°. Globulin dissolved by dilute NaOH. 3*3 per cent, globulin. Eeadings at 

 intervals of two minutes approximately : — 



2560 ohms. 

 2542 „ 



2537 „ 

 2530 „ 

 2522 „ 



2538 „ 



The rise in the last observation followed upon slight shaking of the cell to wash the 

 changed portion of the solution away from the electrodes. Platinum grey electrodes, 

 prepared as Whetham directs, give no trouble. Eeadings with globulin solutions of all 

 kinds remain quite constant after being for 48 hours and longer in contact with them. 



Even with platinum grey electrodes, however, it is necessary so to adjust the cell that 

 the observed resistance does not fall under about 50Q ohms. With a lower resistance, and 

 therefore a larger current, the readings become unsteady and too low.] 



On the assumption that the whole of the drop in electric conductivity is 

 due to association of the salt with the globulin, the above figures show that, 

 at the particular concentration and temperature, 1 gramme of dry globulin 

 combines with 33 x 10~ 5 gramme equivalent of NaCl and 26 x 10~ 5 gramme 

 equivalent of K 2 S0 4 , while to dissolve 1 gramme of dry globulin 10 x 10~ 5 

 equivalent of alkali, or 18 to 36 equivalents of acid are needed. The 

 figures for salt and acid are of the same order of magnitude, and this is what 

 might be expected if salt and acid combine in the same way with the proteid. 



Appendix. 



(Added December, 1900.) 



Viscosity of Solutions of Globulins. — The measurements of this value, very 

 briefly touched upon in the lecture, have been amplified. They show the 

 following interesting features : — 



In dilute solutions of globulins the viscosity, as measured by the rate of 

 flow through a capillary tube, is of the same order of magnitude for each of 

 the three types — acid, alkali, and salt globulin. 



With increasing concentration the viscosity increases, but the increase is 

 much greater for alkaline globulin than for acid globulin, and for acid globulin 

 than for salt globulin. The difference is very striking ; thus, at a concentra- 



