Evening star. [volume] (Washington, D.C.) 1854-1972, 1884-10-25

micrpscepe. the fatty giobules only When it
is falsifled article feather-ke crystalizations
are observed among these fatty gtobules. which
under the polarized light produce the coIors of
the rainbow. This is true, however, as far as
pure butter is concerned when it has not been
melted before the examination, as it also when
melted will show the crystals of margarine and
stearine and in the examination of such case
an erroneous conclusion would apparently be
arrived at. In commerce, however butter is
not submitted to fusion. Many other tests have
been proposed for it's analysis for instance as to
its density, its fusion point. its solubility In
ether and other solvents; different acids, princi-
paliy nitric and sui huric have been proposed,
but none of these tests are reliable and they are
subject to all kinds of error. The only methods
therefore, adopted by the District chemist were
the microscope and, in case of any doubt the
ascertainment OF the proportions of the fatty,
inSOlub!e acids. By saponiticatiou of the butter
by aid of solution of caustic potash in alcohol
adding distilled water as soon as the saponifi-
cation IL complete. the fatty acids are then pre-
cpitated by hydrOchloric acid and received on a
filter, where they are washed with water dried
and weighed Pure butter Yields from Sc to IS
per cent OF fatty acids, while pure "oleomar-
garine," tallow or lard yield 95 per cent of
these insoluble, fatty acids. thus showing a
difference OF from to 8 per cent.
EXAMINING PAYMENTS AND CgMENTs.
The principal labors in the chemists labora-
tory were in connection with the public works
OF the District Daily analyses were made and
reported of the mixture Of the asphalt pave
ments, of hydraulic cement, sand, stone and
all other materials used in all kinds of paveme nt
laid, and on the sewers in process of building.
The tables accompanying the report show the
tensile strength of the various classes and
brands of hydraulic cement used here. The
analyses OF the different brands show their
chemical composition. The report concludes
with the reteraton from former reports that
the cements made in this vicinity are superior
in quality and cheaper than the Rosendale aud
other domestic cements imported from New
York and that by active efforts of the manu-
facturers here these brands of hydraulic cement
are continually improving and rising in quality.
During the year he received from the Post
master General an official appointment as in
spector and superintendent, at stated COM
pensation, OF the concrete pavements being laid
on the ground floor of the general post Office
building. the work to be done after his regular
office hours. After the work had been done
and the compensation paid him the first con-
troller OF the Treasury notified the District
Commissioners that under misconstructiOn of
the law by the Postmaster General the profess
sor had been Illegally paid for the above work.
and they were directed to withhold the amount
from his regular pay. To prevent any embar-
rassment to the Commissioners he at once paid
the amount into the Treasury. where it was
received and placed to the credit of the Dis
trict, though paid him by the Post Office de-
partment.