Intelligence and Miscellaneous Articles. 311 



not. — Separate impression from the XX. Ber. der Oberh. Gesellsch. f. 

 Natur- u. Heilkunde. 



Giessen, Dec. 8, 1880. 



RESEARCHES ON THE SPECIFIC MAGNETISM OF OZONE. 

 BY M. HENRI BECQUEREL. 



Iii the course of my researches on the magnetic rotatory powers 

 of the gases*, oxygen presented some remarkable anomalies, which 

 have induced me to resume the study of the magnetic properties of 

 that gas, discovered by my fathert, and to evaluate the specific mag- 

 netism of ozone. 



For that purpose I fixed above the large electromagnet of the 

 Museum a torsion balance enclosed in a vertical test-tube of glass, 

 in which a vacuum can be produced and into which various 

 gases can be introduced. The torsion-thread employed was a 

 very fine gold wire 32 centims. in length, sustaining a small 

 glass bar consisting of a tube filled with air, and closed at both 

 ends. A microscope was directed towards a mark traced upon the 

 bar, and permitted the latter to be at any time brought back to a 

 fixed position, at about 45° from the line of the poles of the elec- 

 tromagnet. 



When this was magnetized, the small bar was attracted ; and by 

 a suitable torsion of the gold wire the attraction was balanced, so 

 as to restore the bar to its initial position. We know that in these 

 circumstances, in virtue of a principle analogous to the principle 

 of Archimedes, the attraction measured is the difference between 

 the action exerted upon the bar and that exerted upon an equal 

 volume of the ambiant gas. On measuring the attraction in vacuo 

 we have the effect produced on the bar alone ; and the difference 

 between the torsion thus obtained and that which is observed in 

 different gases measures the action exerted by the magnet upon 

 the gas. It was moreover verified repeatedly, by determining 

 the periods of the oscillations of the small bar under the influence 

 only of the torsion of the thread, that the elasticity of the latter 

 had not changed during the experiments. 



The ozonized oxygen was prepared by passing pure and dry 

 oxygen through an effluvia-apparatus like that prepared by M. 

 Berth elot ; and the gas was collected over sulphuric acid under a 

 glass bell furnished with a glass cock. Thence it passed, through 

 pipes entirely of glass, into the test-tube, in which a vacuum had 

 been previously made. 



Notwithstanding these precautions, perhaps by reason of the 

 presence of traces of organic matters (grease, resin), the ozone in 

 the test-tube was rapidly decomposed, and it was not possible to 



* Annates de Cliimie et de Physique, serie 5, t. xxi. p. 289 (1880). 

 t Ibid. ser. 3, t. xxviii. p. 323 (1850). 



