364 Miscellanies. 
The metals oxidize rapidly in water ; are brittle, fixed, and require 
a good red heat for fusion. They sink in sulphuric acid. y keep- 
ing in naphtha, they acquire a coating which renders them less active 
when exposed to water. 
Dr. Hare attempted to separate the mercury from the amalgams 
when solidified by the use of solid carbonic acid, by straining them 
through leather, but the result did not answer his expectations. 
By using solid carbonic acid and hydric (sulphuric) ether, Dr. Hare 
solidified a mass of the amalgam of ammonium. He considers that 
in this case a portion of ether combines with the alloy, without im- 
pairing its metallic character. 
Professor Bache, in behalf of Professor Alexander, of Princeton, 
made a verbal communication of a description of the aurora borealis, 
of September 3d, 1839, as it appeared at Princeton. - 
At about ten or fifteen minutes past eight, P. M. an ill-defined, but 
considerably bright light was seen to extend for some distance above 
e horizon, i in a direction nearly due east ; it was similar, in intensity 
and appearance, to a lunar twilight. Soon after this, a continuous 
arch or zone of light was manifest, extending from the same spot to 
the opposite, or nearly opposite portion of the western horizon. This 
soon separated into two parts,* and, after a short interval, beams of 
light shot up from the eastern portion of the arch, which were speedily 
multiplied in every direction around the observer, aioe within about 
thirty degrees of the trwe (or it might be magnetic) south 
A corona was soon formed, which was at first quite dedistinet, ad 
was not continuous for any great length of time, during the existence 
of the aurora, except at the period of its greatest brilliancy. Atabout 
twenty minutes past eight, this corona was situated in a line with, and 
about midway between @ Aquile and « Lyre. This may be consider- 
ed as a very tolerable approximation to its position, though, from the 
apparent intersection, or, as it might almost be termed interweaving 
of the beams which composed it, it was not often easy to fix upon the 
place of its centre with much precision, if indeed that which seemed 
its centre, did not really change its place; since, at times, it seemed 
to occupy a position very sensibly lower than that which the prece- 
ding observation would indicate. 
At about half past eight, the appearance of the aurora was superb. 
The radiations which extended from the corona, nearly reached the 
izon in every direction, with the exception of those which tended 
he southern space before-mentioned, which, it is believed, was 
