Ray Stannard Baker.

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peratures, from about 30 degrees below zero to 350
degrees above zero Centigrade, with an error rarely
greater than one-tenth of a degree, the staff of the
Reichsanstalt proceeded to make extensive experi-
ments in the determination of temperatures lower
than 30 degrees and higher than 350 degrees.
Mercury boils at 350 degrees C, but if it is placed
under the pressure of gas within the thermometer
tube liquid, it can be kept up to 550 degrees. Pro-
fessor Holborn, with Dr. Day, who, by the way, is
an American, and the only foreign member of the
Reichsanstalt staff, has worked with these gas ther-
mometers for over three years with excellent results,
obtaining a standard thermometer with a range much



A Typical Scientific Institution 179



wider than any heretofore produced, — from 30 de-
grees below zero to 550 degrees above zero. This
thermometer would



measure temperatures
still higher than this
were it not tor the tact
that at this point the
glass begins to soften.
Beyond 550 degrees,
then, other means
must be employed,
and extensive experi-
ments have been made
with what are known
as thermo-electric
junctions. A thermo-
electric junction, such
as is used in the Reich-
sanstalt, is a very sim-
ple contrivance of two
fine wires about four
feet long, fastened to-
gether at one end.
These wires are of

different metals ; in Dr. Dny Experimenting n.vilh

older experiments rhermometers

copper and German silver were used, but more recently
platinum, iridium, and rhodium — the most infusible




i8o Seen in Germany

of all metals — have been substituted. When the
point of connection of these wires is heated, an electric
current is set up, the more heat the more current ; and
by measuring this current the temperature at the point
of junction may be closely calculated. The Reichs-
anstalt has successfully used the thermo-electric junc-
tion for measurements as high as 1,775 degrees C.
with greater accuracy than ever before. Higher than
this the platinum begins to melt, thus putting an
end to the experiment.

In the same way that high temperatures have been
invaded and subjected to measurement, thermometers
have been constructed for measuring low tempera-
tures. Dr. Day showed me a thermometer filled
with clear petroleum ether, the first result of the dis-
tillation of petroleum, — a waste product, by the way.
As a result of testing many different substances, the
capacity of this liquid for resisting great cold was
discovered. It will not freeze even at the tempera-
ture of boiling liquid air, although it becomes
molasses-like a few degrees further down. By
means of this thermometer fairly accurate determina-
tions of heat can be made at a degree of cold hardly
conceivable, — at least 190 degrees below zero- Centi-
grade or over 300 degrees below zero Fahrenheit.

By these various means the range of temperature be-
tween that of liquid air, 192 degrees below zero Centi-
grade, which is nearly at the bottom of the ladder ot



A Typical Scientific Institution i8i

temperature, to 1,775 degrees, where platinum melts,
has been thoroughly explored. Beyond the melting-
point of platinum, and up to the temperature of the
sun itself, the Reichsanstalt has made probably the
best-existing estimates. Indeed, its determinations
of the melting-point of various metals — an investi-
gation of the utmost importance to science and me-
chanics, and as difficult as it is important — are
standard the world over. Some of these tempera-
tures, recently announced, may give an idea ot the
ranges of temperature covered in the Reichsanstalt
investigations.

Centigrade Scale,

The sun, estimated 4,800 degrees

Arc light 3.750 to 4,200

Platinum melts i>775

Argand lamps 1,700 to 1,900

Gold melts 1,065

Mercury boils 350

Water boils 100

Water freezes o

Liquid air boils 192

The history of the scientific attempts to determine
the exact melting-point of gold would fill a good sized
volume. Seven years of investigation have been given
to it at the Reichsanstalt alone, and the figure above
given nearly approaches absolute accuracy.

The work of the second department in testing
thermometers and other heat-measuring devices will



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Seen in Germany



show what a practical hold the Reichsanstalt already
has on the manufacturers of Germany and of the




Professor Hagen, Director of the Technical Department of the Reichsanstalt

world. Director Hagen, who was for years an asso-
ciate of von Helm hoi tz, told me that in 1899 the



A Typical Scientific Institution 183

Reichsanstalt tested over 77,000 physician's thermom-
eters, sent to them by thermometer manufacturers,
17,000 at the home institute and 60,000 at a branch
in Ihiienau. Thousands of other thermometers of
various kinds were also tested. The work consists




'Testing T/iermometers

in careful and accurate comparisons of thermometers
submitted for examination with two or more standard
thermometers, the observations being calculated by
an assistant. When the comparisons are finally made,
the letters P. T. R. (Physikalisch Technischer Reichs-
anstalt) with the number of the instrument is etched



184 Seen in Germany

on the glass, and a certificate is provided giving the
corrections necessary to make accurate readings. All
this is done for a fee of from 60 pfennigs to one mark
(14 to 24 cents) for each thermometer, — merely a
nominal charge compared with the value of the in-
struments. As a result of this certification and the
prestige which it has given to German instruments
for heat-measurement, the annual export of physician's
thermometers from Germany has increased more than
threefold since the Reichsanstalt was organized. It
is significant that the certificates furnished with the
thermometers are printed in nine different languages,
— certainly an evidence of the world-wide influence
of this almost unknown German institution.

Another important work of the Reichsanstalt is the
effort to establish new or more accurate units of meas-
urement. For instance, physicists say that the unit for
the measurement of temperature, one degree, shall be
the degree of heat required to expand a certain amount
of hydrogen gas ^js o^ its volume. This is as close
an approximation to an absolute unit as science can
make, for, having hydrogen gas and the necessary in-
struments, the unit can always be obtained. But in
measuring light there is no such satisfactory scientific
method of measurement, and Professor Lummer has
been engaged in trying to establish one. His ex-
periments are as interesting to the scientist as they are
complex to the layman. Briefly, he has attempted



A Typical Scientific Institution 185

to measure the heat radiated by one square centi-
meter of pure platinum, — platinum being the most
nearly perfect metal, — when heated just to the melt-
ing-point. But platinum is a very hard metal to melt,
and when it does reach the melting-point, it is still




Measuring the Candle-Po-xver of Electric Lamps

more difficult to measure its radiation. As yet, there-
fore, the question is unsolved.

The second department, on the other hand, has so
improved the existing means of measuring light that
its work is accepted the world over. As I have al-
ready mentioned, our own government, through its war



1 86 Seen in Germany

department, has submitted electric lamps to be tested
here and American manufacturers have repeatedly had
standard lamps sent from the Reichsanstalt to furnish a
basis of measurement tor their own product. Indi-
rectly, therefore, the Reichsanstalt assures the accu-
racy of the candle-power on many incandescent lamps
as they come from the American dealer.

The old way of measuring light was to compare
it with an actual candle of a certain size made of
certain fixed materials. At best this process was ex-
ceedingly uncertain, as any one may conjecture who has
seen a candle puffed about by every wave of air. So
Hefner, a German scientist, invented a lamp having
a certain kind of wick and burning amylacetate. When
the flame was 40 millimeters high it was said to equal
one candle-power. The Hefner lamp, being the most
accurate standard now at the disposal of scientists, is
the present standard of measurement; but the Reichs-
anstalt, finding that the burning of this lamp was uncer-
tain and likely to be affected by drafts, devised a small
electric lamp of exactly the same power. This, with
proper control of the electrical current, burns steadily
and continuously, — a nearly perfect unit for meas-
urements. To the Reichsanstalt also the manufac-
turers mav send their lamps to ascertain at what
strength of current they will burn longest, and at the
same time give the most light, to see what kind of
filaments are best, and so on, — all facts of great prac-



A Typical Scientilic Institution 187

tical importance if the manufacturer would make his
wares perfect.

In this connection Professor Lummer has made a
series of determinations of the cost per candle-power
of the various kinds of light in common use (see
table on following page). The results obtained are
of great practical and economic value, inasmuch as
every one is a light- user. Here are his determina-
tions, the unit candle-power being the Hefner lamp.

When the price of materials or energy is cheaper
or dearer than indicated in the table, the price per
hour for candle-power would of course be cheaper or
dearer.

Another series of inquiries, while having great
practical value, leads the way to the solution of
some of the deepest and most interesting problems of
science. These are experiments in the conductivity
of heat and electricity by various metals. In the first
place the Reichsanstalt secured rods of the metals
which by chemical and other methods had been
wrought to a condition approximating absolute purity.
I saw these rods of gold, platinum, silver, and so on,
— the purest metals, probably, in the world. They
were cylindrical in shape, about three-quarters of an
inch in diameter and over a foot long. They will
probably long remain the standard of purity. Begin-
ning with these pure metals, the experimenters sought
to learn all they could about the effect of heat and



i88



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Online LibraryRay Stannard BakerSeen in Germany → online text (page 9 of 15)