St. Paul daily globe. [volume] (Saint Paul, Minn.) 1884-1896, 1884-04-09
ACADEMY OF SCIENCES.

An Interesting Paper by Prof. Dodge
analysts Of FILTERED Water.
A meeting Of the Academy of Sciences
was held last evening with rather small at
tendance. The president, DR.. Elliott, called
the meeting to order andsafter the reading Of
the minutes of the last meeting, which were
approved, paper on ''An Analysis of Fill
tered Water'' was read by Prof. Dodge, of
the state university. He said that the ques
ton of the ways and means of obtaining
sufficiently pure water for drinking purposes
and domestic use in this city is one that had
been several times discussed before the acad-
envy and elsewhere. All admit that it is a
question of importance. Sanitary authorities
had repeatedly informed us what the conse
quences of drinking impure water may be
what they undoubtedly have been
in some localities in this country and in Eu-
rope and what they may be here. Whatever
one source of supply, river water, lake water
well water, cistern water, we know that they
are all liable to contand Patton with impuri-
ties of various kinds, and that certain of
these impurities, especially human eXcreta,
introduce into the water an element of dam
ger, and throw upon those who partake of it
positive risk Of contracting disease. Now
here in Minneapolis, the greater number CT
US are personally concerned with the char
acter of the water of the river, as supplied by
the city water works. We are for the most
part willing to admit that there are worse
waters used than the river water, but at the
same time we are aware that
he river water is not up
to the standard of purity which an intelligent
and Clearly community desires. He has
been giving some attention of late to the
subject of the improvement of water by fl
tration, and more particularly by domestic
filtration. At his residence he has been
using for about year fltering apparatus
which he had applied to the publication of
water, supplied by the city works, and with
satisfactory results. The essentials of the
construction of the apparatus the professor
then represented in figure on the black
board The vessel is of stone ware and con-
sists of receptacle, holding about two gal
Ions, and into which is poured the water to
be filtered. The filtering medium is granu-
lated charcoal or bone black. Another
art of the machine holds the
water after filtration, delivering it from
faucet. The receptacle is emptied and clean
ed from time to time together with sponge
stuffed into cavity as represented in the
figure. 1t would surprise anyone not ac-
Quainted with the subject tie observe the vast
amount of dirt deposited in the receptacle
and sponge after q short time of us. The
results of the analytical tests were paced on
the blackboard. He had submitted the fl
tered water to two particular tests, which were
most important in the case, namely, the test
for ammonia free and albuminoid, and the
permanganate test. On the same day he
took quantity of the unfilterd city water from
the pipe and submitted it to the same analy-
sis and both analyses were con-
Quoted with the utmost care
and with every precaution to obtain correct
results. On comparing the results it was
found that the filtered water showed about
one-sixth the amount Of both free ammonia
| and albuminoid ammonia which was shown
by the water not filtered. The river water
does not show itself decidedly bad through
| the chemical tests, which are not perfectly
conclusive as to the real purity or impurity of
| a water, as they do not show all that is in
water, and hence they need to be supple
mented by other methods of examination,
according to circumstances. For compare
| tive purposes they are very good tests. By
the permanganate test still greater differ
ence between the unfiltered and the filtered
water was found. The filtered water by this
test appeared to be almost as free from or
ganic matter as the specially prepared dis
titled water which We use in connection with
our water analyses, and from chemical
standpoint we should be perfectly satisfied