Evening star. [volume] (Washington, D.C.) 1854-1972, 1884-10-25
WATER, MEEK AND BUTTER.
work Done During the Year by the
District Chemist.

VARIATIONS IN TIE PURITY OF OUR WATER
sUPPLY-HOw THE CHEMIST TESTS MILK AND
BUTTER-ERRORs OF THE LACTOMETER-
THE WAY To DETECT oLEOMARGARINE
AND OTHER MISUNDERSTANDING PAVING
MATERIAL AND CEMENT.
Professor z. j. de Smedt. the District chem
ist in his annual report for the past fiscal year.
submitted to-day. enumerates the operations
analyses and examinations of the Office and lab
oratOry of the chemist during that period. At
the' request of the health officer 237 analyses
were made for his department to determine the
innocent or injurious qualities OF the samples
submitted and their usefulness and influence on
the sanitary condition of the city The analy-
ses wcfe II of water, SO of milk. 176 of butter Q
OF meat and each of vinegar buckwheat and sar-
dimes. During the past five years great many
analyses have been made Of the Potomac water
Great variations were found in the purity ofour
water supply. which are due to climacteric
causes; the principal changes happen after
heavy storms on the upper Potomac or during
long spells OF dry weather when the highest de-
gree OF purity Is reached The extreme differ
ence in the water after such seasons are shown
by tables furnished.
EXAMINATIONS OF MILK
The Importance of pure milk has attracted the
attention OF chemists and psychologists on &C
count Of its manifold uses. it being the main food
OF the infant the invalid and the old. and BEING
daily consumed in large quantities for drinking
and cooking purposes. Many methods have
been Indicated to distinguish the proportionate
quantities of the bodies Of which it il composed
In the analyseslot Prof De Sinedt preference is
given 10 the method adopted by Messrs Cheya-
Her and d Henry, which is as follows: Heat the
cd
acid diluted by two volumes of water: receive
the caseum on a filter, wash the precipitate with
pure water; after this treat the precipitate with
ether, which. after evaporation, gives the weight
or the butter; then the caseum is dried and
weighed The serum (''whey'O with the wash
water isevaporated over a water bath; this gives
the sugar of milk and soluble salts The sugar
can now be Quantitativey determined by the
cupro-potassia liquor or by the saccharimeter;
tne incarceration OF the caseine gives the weight
OF fhe insoluble salts. The difference between
the weight OF the milk and the substances TINS
found Dy the analysis gives the weight of the
water. The general average composition of
milk is as follows: Specific gravity. O3IS: dry
residue (belng casenm SO. butter 4C5, sugar
10 salts "a l2.1o; water, 1925; total 100 co.
The composition Of milk may change accord
ing to different influences. The diminution of
one body. however, necessarily causes the in
crease OF another. The principal correlation
exists between the sugar OF milk and the caseu,n
diminutIon OF sugar Of milk. it should also show
a corresponding increase of caseum and the ap-
pcarance of abUmen. In such case the natural
conclusion is that the alteration is due to a GER
tain patholOgic condition of the COW. or to the
influence OF bad food. But it, on the Contrary
a diminutiOn OF all the constituents of the milk
is found by the analysis. and there is an increase
oi the quantity of the water the adulteration is
evident. The microscope is also a great help in
the examination of milk.
taftnIupfpr N erals act of Ia L;
are0meter which serves to Indicate the quantity
OF water added TO pure milk. 1t also serves to
INDICATE If milk has been skinned or deprived
OF certain portion OF its cream; but the use of
THIS KIND OF instruments may lead to great
errors; for instance. the skinned milk or milk
deprived OF certain quantity Of its cream and
consequently in part OF its butter has greater
density. III, therefore, a certain quantity of
water lis added thereto. this skinned milk NAV
be brought to the density OF pure milk: and the
laetometer would Indicate pure milk, falling to
notice the two authorizations 1t had undergone.
hrst by abstraction Of quantity of its cream
and. afterwards, by addition of water In using
the iaetoneter it is. therefore, necessary to as
(''whey) which ought never to be less than
i-OSI. III less, 1t may be concluded that the
mix mas been watered- The analysis. however
is the only proper method to be applied where
correctness Is required Prof. De smedt sug-
gests that standard ought to be by law adopted
loT Tue quality OF milk. The New York stand
arc adopted by him in his analyses is 12 per
cent OF solid residue. OF which residue % Der
cent at least shall be butter.
DETECTING ADULTERATIoNs IN BUTTER.
The many authorizations Of butter and its
spurious limitations offered in market have led
to careful and extensive investigation thereof.
No less than 176 samples were examined by him.
principally by the aid OF microscope of high
power and one with polarized light The but
Ter examined, when pure, shows, through tho