n oil, 26.5 per cent.; for the Washington
oil, 26.6 per cent.; and for the Middle District oil, 28.2 per cent.

The question now arises, What value has this determination of the
proto-paraffine which may exist in an oil? As before said, a portion
of the paraffine is always decomposed in distillation at temperatures
sufficiently high to drive over the paraffine oils, so the yield of
pyro-paraffine is always less than the proto-paraffine shown to be
present originally. Zaloziecki found this in the case of the several
Galician oils he examined. Corresponding to the 4.6, 5.8 and 6.5 per
cent. of proto-paraffine in the several oils he obtained 2.18, 2.65
and 2.35 per cent., respectively, of pyro-paraffine.

For the present, however, the extraction of proto-paraffine on a large
scale by means of such solvents as amyl and ethyl alcohols is out of
the question on account of their cost. A distillation, under reduced
pressure and with superheated steam, would, however, prevent much of
the decomposition of the original proto-paraffine and increase the
yield of pyro-paraffine.

This study of Zaloziecki's method and the examination of American oils
was suggested by Professor Sadtler and carried out in his laboratory.

* * * * *

TRANSMISSION OF PRESSURE IN FLUIDS.

By ALBERT B. PORTER.

The young student of physics occasionally has difficulty in grasping
the laws of pressure in fluids. His every day experience has taught
him that a push against a solid body causes it to push in the same
direction, and he often receives with some doubt the statement that
pressure applied to a fluid is transmitted equally in every direction.
The experiments ordinarily shown in illustration of this principle
prove that pressure is transmitted in all directions, but do not prove
the equality of transmission, and in spite of all the text books may
tell him, the student is apt to cling to the idea that a downward
pressure applied to a liquid is more apt to burst the bottom than the
side of the containing vessel.

[Illustration: Figs. 1. and 2.]

The little piece of apparatus shown in Fig. 1 was designed to furnish
a clear demonstration of the principle under consideration. It is
essentially an arrangement by which a downward pressure is applied to
a confined mass of air or water, and the resultant pressures measured
in the three directions, down, up, and sideways. By means of a broken
rat tail file kept we