RADIATE APPEARANCES 41 



If one takes into regard the errors which necessarily 

 result from the somewhat irregular shape of the drops, the 

 agreement in the size of the drops with that which they 

 previously possessed in glycerine (see Table III.) is quite 

 striking. I have added to Table V. in square brackets the 

 differences of measurement as compared with Table III. 

 This reaches the maximum in one drop of 6 per cent. I do 

 not doubt that the repetition of the experiment would have 

 succeeded oftener still, but I had no occasion to continue it 

 further. 



If the demonstrable and indubitable fluidity of the froth- 

 drops be taken into consideration, the observations here set 

 forth upon the plasmolysis of the drops, as the process may 

 aptly be termed, may serve to remove all doubts which could 

 be raised, and which have already been raised by Frommann 

 (see further below), as regards the frothy nature of the drops 

 prepared by me. 



Since to many people the notion of a diffusion of watery 

 fluids through lamellae of oil is somewhat unusual, though the 

 experiments related here prove it occurs beyond a doubt, I 

 hare also performed some experiments on this point with 

 aniline colours. If the drops are brought into a moderately 

 concentrated solution of methyl green in water, they are 

 coloured strongly greenish blue after about twenty -four 

 hours, and after forty-eight hours the colouring had even 

 gone completely through the larger drop (diam. about 1*5 

 mm.), though after twenty-four hours it still showed a white 

 centre. By pressing the drops more strongly it could be 

 plainly made out that the contents of the alveoli were 

 coloured green, and hence the solution of methyl green had 

 penetrated into the alveoli. 



3. Radiate Appearances in the Drops of Oil -Foam 



In good froths, which have stood quietly for some time, 

 a more or less pronounced radial striation can be not in- 

 frequently observed, as well beneath the whole surface, as 

 round the larger vacuoles of the interior. This radiate 

 appearance can usually be increased, or even produced, if, 



