Magnetism — Meteorology, ^c. 16^ 



ends of a straw, suspended by its middle with a silk fibre without torsion. 

 The two poles of the needle are placed so as to render the earth's action 

 upon it almost nothing, M. LebaillifF has modified the apparatus in va- 

 rious ways, as M. Becquerel has remarked its extreme sensibility de- 

 pends on the length of the arm of the lever, at the end of which the mag- 

 netic action is exercised, and on the neutralization of the earth's action. 

 This apparatus has led to the following curious discovery. 



4. Singular Magnetic Property of Bismuth and Antimony. — When 

 either bismuth or antimony is brought near the poles of M. Labailliffs 

 needle, above described, they exert upon both poles a very decided repul* 

 sion. M. Becquerel, who mentions that he saw this experiment with asto- 

 nishment, remarks that this doubly repulsive property has been recogniz- 

 ed only in these two metals. An account of this curious fact was laid be- 

 fore the Philomathic Society of Paris on the 31st March 1827.— Xe Globe, 

 Avril 3, 1827. 



METEOROLOGY. 



5. Hourly Meteorological Observai inns on the 17 th July. — Those me- 

 teorologists who have hitherto made the hourly meteorological observations 

 in pursuance of the recommendation of the Royal Society of Edinburgh, 

 are earnestly requested to continue them on the seventeenth of July. In con- 

 sequence of a typographical mistake in the notices to Correspondents in our 

 last Number it was called the 15 th June. 



6. Luminous Spots near the Horizon* — M. Atwater in a memoir on the 

 climate of Ohio, in Dr Silliman's Journal^ remarks that, before a storm, he 

 has often noticed in an evening of the latter part of autumn, and some- 

 times in the winter, a phenomenon which he never saw on the east side of 

 the Alleghanies. Some one spot or spots near the horizon in a cloudy night 

 appeared so lighted up, that the common people believed there was some 

 great fire in the direction from which the light came. He had seen at 

 once two or three of these luminous spots not far from each other ; gene- 

 rally there was but one, and a storm, invariably proceeding from the same 

 point near the horizon, succeeded in a few hours. 



II. CHEMISTRY. 



7. N^ew compound of selenium, and oxygen. — Professor Mitscherlich has 

 discovered a new acid of selenium, consisting of one atom of selenium and 

 three atoms of oxygen, and consequently analogous in composition to sul- 

 phuric acid. Its appropriate name will of course be selenic acid, since it 

 contains more oxygen than the compound hitherto known by that name; 

 while to the latter, the composition of which is similar to that of sulphu- 

 rous acid, the term selenious acid must hereafter be applied. The isomor- 

 phism of selenium and sulphur is already known, and principally esta- 

 blished from the identity of form of the compounds, which they produce 

 with lead, — sulphuret of lead, or galena, and seleniuret of lead, both of 



