Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed
År: 1909
Sted: Kjøbenhavn
Sider: 185
UDK: 6201(09)
Emne: Trykt hos J. Jørgensen & Co. (M. A. Hannover)
On the development of testing of materials in the north and on the work of the danish states testing laboratory in Copenhagen (english translation)
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The Clay-Laboratory has, of course, on a large scale dealt
in researches on the applicability of clay and other raw-materials
for the producing of bricks.
The first greater research of this kind treated on:
metrical Examinations of some Danish
of Clay (Report VII of the Laboratory).
To make these researches with sufficient accuracy
necessary to procure a furnace by means of which not only the
sufficient temperature could be reached but also be regulated
and especially kept constant over a longer period. On this proving
very difficult with the existing gas-furnaces it was resolved to
construct an electric furnace.
For some former experiments made for the Danish States
Testing Laboratory Mr. Absalon Larsen, then M. A., now Pro-
fessor of the Royal Polyt. Institute, had for another purpose em-
ployed as an electric furnace an externally screwcut chamotte-
cylinder with a winding of nickel wire inlaid in the screw-
worms, which was run through by electricity. The Laboratory
being still in the possession of this furnace, it was decided to
employ it for the chamber itself of the new electric furnace.
During the said experiments, however, no higher temperatures
than about 1000° Centigrade had been attained, wherefore it was
resolved to try first how high temperatures could be reached
on the cylinder being well isolated.
The cylinder was then inwrapped with a double nickel wire,
the diameter of each wire being 1 mm. The inwrapped cylinder
was put down into a cesspool of salt glazed clay in the bottom
of which was a layer of sand, then asbestos flakes and finally
a layer of kaoline. The cylinder was then imbedded in a layer
kaoline separated by an asbestos cylinder from an outer layer
asbestos flakes. The* temperature was observed by means
Le Chatelier’s pyrometer the junction of which was placed
the middle of the chamotte cylinder. At the top the cylinder
was shut with a chamotte stopper in the middle of which was
a hole through which the pyrometer could come down.
At a temperature of about 1400° Centigrade reached after
about 2 hours the wire was burnt over, but it appeared clearly
from the table drawn up of the rising of the temperature, that
if the winding had been platinum, a considerably higher tem-