62 Scientific Intelligence. 
and became polar, but it was a much feebler magnet than the 
previous specimen. Demagnetization was afterward nerforinel 
more easily than at first. 
still more impure specimen was treated, but with the means 
at hand it was not perfectiy demagnetized, although so nana was 
this done that only traces of magnetism were i ati 
The result of our work can be stated as follow 
(1 pt heat developed by reversals of Slaghetiention is proba- 
bly due induction currents, and not to molecular vibrations; 
for socuieruble changes in the molecular structure of different 
specimens of ir so and steel fail to show differences in the amount 
of heat developed 
(2) The heating of iron cores o electro-magnets, which are sub- 
mitted to alternating currents, is — to the surface until con- 
duction equalizes the heat of the ¢ 
he musical note emitted By the core is the note of the coil, 
due to dies number of reversals of the machine, and is merely 
strengthened by the metallic core ya the electro-magnet. This 
note should not, therefore, be used as an argument in favor of 
molecular vibrations of magnetic gartinlee. 
(4) eased bs on demagnetization confirm what has long been 
known in regard to the effect of vibrations and shocks upon the 
magnetic condition of iron and steel. They do not invalidate our 
results upon the heat produced by reversals of magnetization; for 
a very slight change in position of the molecules might affect the 
magnetism of a bar, and yet be insufficient to produce the great 
es A observed in the armatures of dynamo-electric machines.— 
Proceedings American Acad, Arts and Sciences, May 29, 1883. 
11. On the properties of water and ice ; by Orro PErrersson. 
methods of jueswvidion In regard to the experiments with pure 
water, a series of tables gives the results of the experiments on 
the expansibility of pure water (ice) at the different iiss gee 
employed. The most important point brought out in them 
this : that the volume of ice, even the purest which can be cometh 
decreases with a rise in temperature when near the melting point 
and this is the more marked as the amount of salt contained in 
cee ater increases. In regard to this the author remarks that, 
“It is impossible to decide if absolutely pure water would be en- 
tirely free from this weakness or not, since we cannot assume that 
water, which has boiled for a quarter of an hour or more in @ 
