PHYSICS AND NATURAL HISTORY, OF GENEVA. 265 



which M. Chaix has added his experiraeuts upon the proportion of solid, 

 matter contained in the water of the Arve. 



On the 27th of jSIovember of last year occurred that remarkable rain 

 of meteors, which seemed to confirm the hypothesis that shooting stars 

 are produced by the disintegration of comets. M. Plantamour gave to 

 the society the data for the solution of 1 he question, to which the attention 

 of the society w<is again directed by M. E. Gantier, in the coarse of a 

 notice of the presumed discovery of the comet of Biela by an astronomer 

 of Madras. 



I complete the notice of astronomical researches by mentioning the 

 remarkable instance communicated by M. Thury of astronomical visibility. 

 He observed, by means of his small refractor, with great clearness, on 

 the night of the loth to IGtli of June, the star Antares and the small 

 blue star near it. 



Want of space permits me merely to recall to your memory, without 

 analyzing it, the communication of M. Soret in regard to his compara- 

 tive researches between thermal solar radiation and that of a body 

 heated in the oxyhydric flame. These researches, which modify the 

 assertions of P. Secchi in regard to the temperature of the sun, have 

 been published. I would say here, that it is our custom, in our annual 

 account of the proceedings of the society, to confine ourselves almost 

 exclusively to communications which have not been laid before the 

 public. I give, once for all, this explanation, to account for the more or 

 less brief notice of some of the subjects which have been discussed at 

 our sessions. 



M. Wartmann discussed the theory of the perception of color, which 

 admits three systems of nerves, corresponding to the three fundamental 

 colors, and opposed to this theory certain observed facts; in particular, 

 the fact that certain Daltonians do not perceive color, but only a con- 

 trast of light and shade of different intensities. 



Information in regard to the aurora borealis has, from time to time, 

 been sent to me by observers of this phenomenon and by savaus 

 interested in the subject. I have communicated to the society the 

 principal inferences drawn from a work of M. Boue, upon the concord- 

 ance of austral and boreal auroras which he sent me in a letter, and 

 also those from the researches of M. Lovering, who has united in a 

 catalogue more than 12,000 observations of auroras. 



M. Marignac has given us the result of his experiments upon the 

 identity of the heat of fusion and the heat of solution. The tem- 

 perature of solution of a body whose point of fusion is very low was 

 observed during the cooling, and particularly as it passed the point of 

 fusion. There was no sudden change, nothing anomalous, as it passed 

 this point ; and M. Marignac therefore concluded that the heat of fusion 

 is identical with that of solution. For this experiment a solution of 

 spermaceti in alcohol was used; the point of fusion was at 48^ C. The 



