376 Dr. H. Garrett on the Mscos'ity and 



(5) The oscillating disk method gave much higher values 

 for ri than the transpiration method, although Konig found 

 close agreement, with the two methods, for homogeneous 

 liquids so long as the viscosity did not exceed 0'018 

 gr./cm. sec. 



(6) |3 gelatine, i. e. gelatine which has been boiled for some 

 time, does not show these results. 



With silicic acid the results obtained were these : — 



(1) No perceptible increase of logarithmic decrement 

 within a few hours but a marked increase of viscosity (by 

 both methods) within longer periods. Thus a 3*67 per cent, 

 solution showed an increase of about 200 per cent, in the 

 value of Tj in four months. Shaking a solution, whose vis- 

 cosity has thus increased, with air reduces the viscosity ; but 

 shaking it in a vacuum increases ?/. 



(2) A solution which has been raised to the boiling-})oint 

 and reduced to the original temperature shows increased 

 viscosity; if cooled and warmed to the original temperature 

 decreased viscosity. 



(3) In the case of silicic acid the log. dec. was not much 

 influenced by occasional disturbances. 



(4) The decrement measured after large swings was — 

 unlike gelatine — greater than without such preliminary 

 oscillations. 



(5) As the amplitude of swing became smaller the log. 

 dec. grew larger and attained a maximum after which it 

 again became smaller. 



(6) The oscillating disk method again gave considerablv 

 higher values for the viscosity than the transpiration method, 

 even when the viscosity was not much greater than that of 

 water. 



With alhumen solutions the following results were ob- 

 tained : — 



(1) Gradual increase of log. dec. similar to gelatine, the 

 decrement being again a linear function of the time during 

 which the disk was immersed in the liquid. 



(2) The decrements taken after one or two large oscillations 

 were — unlike gelatine but like silicic acid — larger than 

 ^^-ithout such swings. 



(3) Like silicic acid also the first decrement measured dimng 

 a series of oscillations is smaller than the next and here also a 

 maximum decrement is observed. 



(■4) The disk method gave much higher values for 77 than 

 the transpiration method, but what was most noticeable was 

 that boiling reduced ?; as got from the disk method but 



