The Saint Paul globe. (St. Paul, Minn.) 1896-1905, 1897-07-25

true, but that needles and such objects
could be made to keep upon the sur
face of the water with comparatively
little effort. I was really astonished, for
no matter how much a man may be-
neve in a theory, it always astonishes
him to hear that he is right, as he,
like every one else, is always consider
ing the difficulties, the obstacles which
stand in his way.
AT the time of my first experiments
I saw little prospect of succeeding in
floating a ring with clean surface,
for all the treatises on physics [ had
read state that to float a metal on
water it's surface must be coated with
a film of grease. A ring of aluminium
seemed the more likely to float, be-
cause this metal has a peculiar repel-
liant action on melted alloys, like or
binary soldiers. made a ring of alumni
mum fifty millimeters in diameter, out
of wire l millimeter thick. 1t fioated on
water. AS gradually added weight to
the ring it sank deeper and deeper in
a depression in the water, till having
reached a depth of five millimeters it
broke through the water Surface. The
total weight required to make the ring
break through the surface was 2.6
grams.
In subsequent experiments 1 floatad
a ring of els millimeters In diameter
made of aluminium rod 81 millimeters
in diameter. This ring weighed So
grams. To float this ring requires a
steady hand and patience; but a ring
made of aluminium rod 3.15 millimeters
In diameter is easily floated. With this
ring may be made an interesting ex-
pertinent A ring with fine wire yoke
and cup weighs ABS grams. One gram
added to the ring causes it to sink,
giving 5.435 grams as the breaking
weight. The unloaded ring therefore
weighs 10 per cent less than the break
ing weight. If from any cause, such
as the gathering of dust on the water,
or the contamination of it's surface
from the vessel holding it, the surface
tension should be weakened 10 per cent
then the unloaded ring will sink. This
weakening of the surface tension is
readily and rapidly brought about bv
pouring Vapor Of ether on the water
When this vapor reaches the water the
ring moves to and fro in a tremulous
manner and then sinks.
I'm my ignorance, saw in these ex-
periments a property Of f1otation pecu-
liar to aluminium. Experiment, how
ever, soon showed me that all metals,
with clean surfaces, from platinum of
density Of IL, float on water When
and with whom originated the erroneous
statement, that metals to float must
have their surfaces creased, L have not
been able to discover; but this error has
been copied from one treatise on ply
sizes into another for about a century
IF the platinum ring be loaded to,
say, one-tenth of the weight required
to make it sink and then fioated on
freshly distilled water, it will sink
when, from any cause, the surface ten
sion OF the water has been lessened
10 per cent. The duration Of fiatation
Of the ring is variable. On one day it
hoated only during two hours; on an
other day it f1oated for nine hours: on
another day five hours The same ring
loaded so that it lacked 80 per cent Of
the breaking weight f1oated during
sXty-siX hours. The contamination Of
the water seemed more rapid during
dry, windy and dusty weather than
during, or just after a rain. The con-
tamination, however, also proceeds
from the vessel, either Of glass or of