onsiderable extent during the
reaction.

_Acetic acid_ and _benzene_ are both decomposed with violence, their
cold vapors burn in fluorine, and when the latter is bubbled through
the liquids themselves, flashes of flame, and often most dangerous
explosions, occur. In the case of benzene, carbon is deposited, and
with both liquids fluorides of hydrogen and carbon are evolved.
_Aniline_ likewise takes fire in fluorine, and deposits a large
quantity of carbon, which, however, if the fluorine is in excess,
burns away completely to carbon tetrafluoride.

Such are the main outlines of these later researches of M. Moissan,
and they cannot fail to impress those who read them with the
prodigious nature of the forces associated with those minutest of
entities, the chemical atoms, as exhibited at their maximum, in so far
as our knowledge at present goes, in the case of the element
fluorine.--_Nature._

* * * * *

APPARATUS FOR THE ESTIMATION OF FAT IN MILK.

By E. MOLISABI.

[Illustration]

The author, after criticising the various methods for estimating fat
in milk which have been proposed from time to time, agrees with Stokes
(_Analyst_, 1885, p. 48), Eustace Hill (_Analyst_, 1891, p. 67), and
Bondzynsky (_Landwirth Jahrb. der Schweiz_, 1889), that the method of
Werner Schmid is the simplest, most rapid, and convenient hitherto
introduced. The conditions tending to inaccuracy are: The employment
of ether containing alcohol; boiling the mixture of milk and acid too
long, when a caramel-like body is formed, soluble in ether; the
difficulty of reading off the volume of ether left in the tube, owing
to the gradations of the instrument being obscured by the flocculent
layer of casein; when only a portion of the ether is used, fat may be
left behind in the acid mixture, as shown by Allen (_Chem. Zeit._,
1891, p. 331). The author believes that by the invention of the simple
apparatus represented in the accompanying figure, he has rendered the
process both accurate and convenient. This consists of a flask B of
about 75 c.c. capacity, which has a glass tap fused on, with two
capillary tubes attached, the one passing upward, the other downward.
The neck of flask B is ground into the neck of flask A, which holds
about 90 c.c. Either of the flasks can be placed in communication with
the external air by the opening _a_. The ether must be previously
washed with one or two tenths of its volume o