268 
made from the butter fats. Below 40° the particles of fat are so 
hard that they do not readily adhere to each other when brought in 
contact, so that they retain their original size, but may become 
somewhat distorted and angular from ‘the blows received. Above 
the melting point of the fat in any emulsion, the globules become | 
more and more divided by agitation, so that they are continually 
going farther and farther from the state of butter, but in this case 
the globules always retain their spherical form. The following 
experiment shows that milk behaves in the same way. 
The number of globules in a sample of new milk was determined 
and found to be 159 in .0001 eubic millimeter. ‘This milk wasthen 
thoroughly stirred with an egg beater for several’ minutes, it being 
kept at 100° F, or several degrees above the melting point of its fat. 
The number of globules was ‘then determined again and found to be 
174 in the same volume. The stirring was repeated twice more 
under the same circumstances as before, the globules after each 
churning being respectively 231 and 283 in 0001 cubic millimeter. 
Another experiment of the same nature as the above, but in which 
the number of globules whose diameters were greater than one divi- 
sion of the micrometer: scale (.0024 millimeter), was also deter- 
mined, gave the following results: 
The total number of slobules in .0001 cubic weflHthetae of the 
milk was found to be 284, and the number in the same volume hay- 
ing diameters above 0024 millimeter, 136. After churning for 'sev- 
eral minutes at 100° F. there were found 350 globules in .0001 ¢.mm. 
and of these onlv 125 had diameters above .0024 mm., showing 
clearly that the number of small globules had been increased, and 
the larger ones diminished, % 
The microscopical examination of the milk in both of these exper- 
iments, before and after the several churnings, showed no difference 
in the appearance of the globules except that the number of small 
ones was largely increased. The globules were not distorted in the 
least, nor were any broken membranes discovered, although in the 
first case the number of globules had been nearly doubled by the 
churning. 
4. Action of ether. Probably the argument most often advanced 
in favor of a membrane has been that ether shaken up with milk 
fails to remove the fat, unless a little alkali or dilute acid be added, 
the veason assigned being that the membrane enclosing the fat pre- 
vents the ether from coming in contact with it, but that this mem- 
brane is dissolved by the alkali or acid and the fat set free. This is 
decidedly a misinterpretation of the fact, which could scarcely have 
been made by one who had tried the experiment, for while it is true 
that ether thoroughly incorporated with milk by shaking does not 
remove the fat, it is no less true that the ether itself is not separated 
but remains incorporated with the milk as an emulsion, and there 
is evidence that it is in combination with the fat. For while 
the butter globules of milk as seen in the microscope are highly 
refractive and have the peculiar appearance described before, the 
drops of this emulsion are nearly colorless, and in refractive power 
differ little from the surrounding liquid, none of them having the 
characteristic appearance of the fat globules of milk. Besides arti- 

