168 Intelligence and Miscellaneous Articles, 



know : as regards glass, Knapp's ' Chemical Technology ' contains 

 remarks from a professional point of view. Whether the explosive 

 force of the bursting tears is a direct action of the tensions arising 

 from sudden cooling, or whether the glass particles loosened by a 

 wave of agitation impinge against each other like elastic bodies and 

 are immediately repelled, is a further question the decision of which 

 is closely connected with a clear view of the nature of hardened 

 glass. More competent physicists may perhaps find themselves 

 incited by my communication to devote their attention to the matter. 

 • — Poggendorff's Annalen, March 1867. 



Tubingen, February 4, 1867. 



EXPERIMENTS ON THE MAGNETISM AND DIAMAGNETISM OF 

 GASES. BY M. J. CHAUTARD. 



All physicists are aware with what success the question of the 

 magnetism and diamagnetism of gases has been treated and solved by 

 Messrs. Faraday, Pliicker, and E. Becquerel. My reason for advert- 

 ing at present to a well-established scientific point is, that it has not 

 entered into the course of instruction ; and there are not, as far as I 

 know, experiments which can be shown to a numerous audience, 

 these phenomena being somewhat difficult of execution, while, on 

 the other hand, they are never sufficiently marked to strike persons 

 unfamiliar with these delicate investigations. 



The use of soap-bubbles produced at the end of tubes of pipeclay 

 lias been successful, and in the case of oxygen has enabled me to ob- 

 tain an energetic action which could be converted into a considerable 

 oscillatory motion, by the successive magnetizations and demagneti- 

 zations of an electromagnet. I used Ruhmkorff's large electromag- 

 net arranged for Faraday's experiments, and worked with a battery 

 of twenty- five to thirty elements. The solution of soap is mixed with 

 a certain quantity of glycerine (the proportions are the same as for 

 Plateau's experiments) ; the tube of pipeclay is fixed in a clamp of 

 such a height that the bubble formed at one end is above the poles 

 of the magnet, and at a distance of 2 or 3 millims. ; at the other end 

 of the same tube is a caoutchouc tube connected with a bladder filled 

 with oxygen : the experiment being ready, the bubble is illuminated 

 by means of an oxyhydrogen light. A sort of magnetic gas-pendu- 

 lum is thus formed, the movements of which in a large lecture-hall 

 are as visible as those of the small iron pendulum. 



Another perfectly easy experiment may be made with magnesium 

 vapours, or rather the white cloud from burning magnesium. By 

 burning the metal just below the conical polar extremities of the 

 electromagnet, as soon as the current passes, the column of smoke 

 divides laterally and takes the shape of a well-marked U. It is a very 

 curious and easy lecture experiment. — Comptes Rendus, June 3, 1867. 



u\ jo^*7 



-• 



