PHYSICS AND NATURAL HISTORY OP GENEVA. 239 



enon of the coloration of the waters of the Rhone, but, as was objected 

 at the time, will not suffice for a complete explanation. 



An interesting communication was received from M. Mousson, of 

 Zurich, through M. Soret, the object of which was to show that, in 

 the phenomenon of water- spouts, a superior degree of validity must 

 be conceded to the theory which refers them to the meeting of two 

 currents of air exerting a gyratory force over that which makes them 

 depend on an attraction produced by the electric tension of a cloud. 

 M. Mousson has succeeded in calculating what force of aspiration is 

 to be supposed in the case of a water-spout, and does not find it out 

 of proportion with what is possible upon his own theory. 



It is to M. Mousson that we are also indebted for some curious 

 experiments on the effect of strong pressure in hindering water from 

 solidifying even at very low temperatures, such as 20° below 0°. 

 These experiments, communicated first to the Helvetic Society of 

 Natural Sciences, were imparted also to our own. 



Here, then, we find ourselves on the confines of physics, properly 

 so called, and we enter completely upon them in recalling the com- 

 munications of M. Soret and M. De la Rive on the remarkable facts 

 respecting the congelation of water observed by M. Forbes, M. Tyn- 

 dall, and M. Faraday — facts which prove the error of considering only 

 the influence of temperature to be concerned in the solidificatiom of 

 water, without taking cognizance of that of the molecular attraction 

 which plays so important a part in this as well as in other crystalliza- 

 tions. 



It is to electricity above all that the greatest number of communi- 

 cations this year relate in what concerns physics, properly so called. 

 First come those of M. Volpicelli on the electrostatic induction, made 

 one by himself in person, the other through the medium of M. Soret. 

 A great number of experiments, conducted under varied conditions, 

 and subjected to different modes of proof, seem to have uniformly 

 strengthened the confidence of M. Volpicelli in his ideas on the theory 

 of induction; but, without entering into details, we here merely re- 

 mark that it has been objected that these experiments may be also 

 interpreted in a sense favorable to the older theory, so that, although 

 very well performed, they cannot be deemed perhaps as conclusive 

 as he maintains, at least in that relation. 



Professor Wartman favored the society with an account of some 

 attempts he had made, on occasion of the transatlantic cable, to deter- 

 mine the effects of pressure on electric conductibility. In submitting 

 a copper wire covered with gutta percha to a pressure exceeding 

 thirty atmospheres, he observed a small diminution of conductibility,. 

 recovering, however, its primitive value when the pressure ceases. 

 He has also observed that strong compression on any member — an 

 arm, for instance, of a person conveniently seated for the purpose — 

 determines a slight but sensible current to a galvanometer of 2-1,000 

 coils, in a contrary direction to that of the current which would be 

 due to the contraction of the same member. 



M. Tirtoff, a learned foreigner, who was present at one of our ses- 

 sions, communicated some experiments made with a view to ascertain 



