during the Year 1828. 427 



tried to find the law of these modifications, and arrived at this 

 remarkable result. " When two colours, A and B, are seen 

 simultaneously, the complementary colour of B is added to A, 

 and the complementary colour of A is added to B." The 

 colours appear quite different, and besides, as white appears 

 more brilliant, and a light colour becomes lighter, when seen 

 simultaneously with a dark colour, which in such a case itself 

 acquires intensity, it results, that the contrast takes place in 

 the colour, and in that which dyers call depth of tone. M. 

 Chevreul remarks, that in explanations which several natural 

 philosophers have given of accidental colours, two very differ- 

 ent cases have not been sufficiently distinguished. The first 

 is that in which the eye, for instance, having long looked at a 

 little square of red paper, placed on a white ground, suddenly 

 moves to a part of the white ground. It then sees a little green 

 square, which is. the complementary colour of red. We can 

 very well conceive, with M. S. Scherffer, in this case, how that 

 part of the retina, on which the image of the red square is 

 painted, being fatigued with this sensation, ceases to look at 

 it, and still seeing the white, that part of the retina fatigued 

 with the red must receive a much stronger impression of the 

 complementary colour of the red, and thus must se© a green 

 square. But in a case where M. Chevreul has studied acci- 

 dental colours, there are two equal zones, contiguous, and dif- 

 ferently coloured, which are seen simultaneously, and the 

 complement of one of the colours acts, not on that part of the 

 retina which sees this colour, but on the part which sees the 

 other colour. The learned author intends to return to the 

 study of these phenomena, to the consideration of which he 

 has been led by accident. 



M. Fourrier read a memoir, entitled " Experimental Re- 

 searches on the Conducting Faculties of Thin Bodies exposed' 

 to the action of Heat, and a description of a new Thermometer 

 of Contact." 



The literary undertaking of the Baron de Ferussac, which 

 has now existed for five years, is still continued, and, by beings 

 in general circulation throughout France, greatly contributes 

 to the endeavours which are constantly making towards the 

 perfection of science. The object of this work is to publish 

 " A Universal Bulletin of Science and Useful Arts;" and 

 the different subjects contained in it are indicated by the fol- 

 lowing titles: — 



Mathematical, Astronomical, Physical and Chemical 

 Sciences. Geology and Natural Sciences. Medical Science, 

 Anatomy, and Physiology. Agriculture and Economy. 



F F 2 



