296 Chronicles of Science. [Apyril, 
descends towards the horizon. These bands, considered as to their 
real constitution and origin, have been the subject of long and 
persevering researches by the author, the principal results of which 
are contained in the memoir submitted. The bands have been 
resolved into fine and well-defined lines, visible in different degrees 
at all heights of the sun. A variety of proofs allow of distinguishing 
with much probability these particular or tellwrie lines from the 
lines pre-existing in solar light. Lastly, if the whole of these lines 
appear to have the terrestrial atmosphere for a common origin, a 
certain number of them would appear to be caused by the presence 
of the vapour of water in the atmosphere. The memoir gives a 
special account of the author’s experiments on the Faulhorn—that 
is to say, at a height of 2,683 metres—where he found that these 
telluric Imes were much less visible than in the plain. It contains 
also an account of an experiment made at Geneva, which seems to 
show more conclusively that the cause of these lines resides in the 
atmosphere. The author made a large bonfire at night, and 
examined the light first close by, and then at a distance of twenty- 
one kilométres. In the first case the spectrum remained continuous ; 
but at the distance just mentioned the telluric lines were clearly 
geen. 
In a memoir by M. J. Nicklés, “On the Effects of Colouration 
and the Extinction of Colours produced by Artificial Lights,” the 
author has suggested a good lecture experiment. With the following 
pigments he paints a spectrum, which shows all the colours either 
by gas or candlelight, but shows only black and white with a soda 
flame (alcohol and salt). 
Colour by daylight. Pigment. Colour by Soda flame. 
Red Ochre Black. 
Orange Biniodide of mercury : 
Yellow Chromate of lead } White. 
Green Manganate of baryta 
Blue Aniline blue } tia 
At a recent meeting of the Chemical Society, Mr. C. R. Wright 
read a paper, entitled “Contributions to our Knowledge of the 
Chemical Action of Sunlight upon Sensitive Photographic Papers.” 
Following the method adopted by Mr. McDougall, and described in 
his paper (‘Journal of the Chemical Society,’ vol. i., p. 183), the 
author proposed to determine the relative degrees of sensitiveness 
exhibited by papers coated with the chloride, bromide, and iodide of 
silver, and mixtures of these, in the proportion of single equivalents, 
in the presence of a constant excess of nitrate of silver. The con- 
clusions established by the author’s experiments are stated in the 
form of eight propositions ; but the general nature of the results 
may be gathered from the subjoined table, which describes the rela- 
a a 
