FAT. 5 



which was freshly drawn, and cooled simply by radiation. Under 

 these conditions the author has obtaine;d evidence that the fat 

 globules are liquid. Storch gives no indication as to the con- 

 dition of the milk used by him, but it is the common practice 

 in Denmark to cool all milk to a very low temperature with ice 

 immediately after milking. These conditions, according to the 

 author's experience, facilitate the solidification of the fat. It is 

 not improbable that the apparent discrepancy between Bechamp 

 and Storch is due to a difference of conditions. 



In concluding that the staining of a layer round the fat globules 

 proved the presence of a solid membrane, Storch appears to have 

 overlooked the surface energy of small particles, which would 

 cause a layer composed wholly of liquid to be formed round 

 <'ach globule. The appearance noticed by Storch is quite explic- 

 able without the assumption that a membrane exists, and, 

 indeed, is somewhat at variance with this view. If there were 

 a solid or mucoid layer it should have a sharply defined outer 

 edge. According to Storch's description this is wantins; ; the 

 staining is deepest nearest to the globule, and fades imperceptibly 

 away, an appearance quite compatible with the view that a 

 condensed liquid layer is present. 



Though data do not exist for calculating the force with which 

 .1 semi-solid layer would be held by surface energy, it appears 

 leasoiiiible to suppose that it would be impossible to remove this 

 liy churning — i.e., friction between globules — therefoie butter 

 could not be made were Storch"s hypothesis correct. 



By homogenising cream — i.e., breaking up the fat into ver}- 

 minute globules — it is found that it is impossible to ihurn the 

 fat into butter ; this operation woald certainly remove a mem- 

 brane, and accordinn to Stoich's theory should facilitate churning. 



If Storch's view were correct, it would be expected that the 

 membrane would bear such a proportion to the smallest fat 

 globules that their density would be eijual to that of the milk 

 serum, and the last traces of fat could not be removed by centri- 

 fugal tone. Bv means of an efficient separator it is possible, 

 on running milk twice, to obtain samples of separated milk in 

 which the percentage of fat is so small that it does not reach 

 the second place of decimals per cent. ; this fact, while not 

 definitely disproving Storch's view, is further evidence agamst it. 



The following facts seem to definitely disprove Storch's view- :— 



(1) The ratio of the milk-sugar and protein in cream is the 

 same as in the separated milk. 



(2) When milk or cream is stained no layer can be detected 

 round the globules until the aqueous portion is washed away. 

 There are. however, many stained particles (probably mucoid 

 protein) quite independent of the fat globules. 



