132 



the alembic. The air from the apparatus was expelled by hydrogen, 

 desiccated by passing through the chloride of calcium and quick-lime 

 in the adopter. The distillation was conducted by applying heat 

 principally to the upper part of the amalgam, to prevent an explosive 

 ebullition. The mercury being distilled off, which requires a bright 

 red heat in expelling the last portions, the metallic radical remained 

 in the crucible. 



The metals oxidize rapidly in water; are brittle, fixed, and require 

 a good red heat for fusion. They sink in sulphuric acid. By keeping 

 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 

 impairing its metallic character. 



Professor Bache, Reporter, informed the Society, that No. 7 

 of the Society's Proceedings, was now printed. 



Professor Bache, in behalf of Professor Alexander, of Prince- 

 ton, 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 

 the horizon, 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, except within about 

 thirty degrees of the true (or, it might be, magnetic) south. 



A corona was soon formed, which was at first quite indistinct, and 

 was not continuous for any great length of time, during the existence 



*Two arches, it is believed, were at this time formed, and either separated 

 throughout their entire extent, or united only near their extremities; but this 

 my notes do not explicitly state. 



