54<6 Intelligence and Miscellaneous Articles. 



the Rev. W. R. Dawes, I feel a little more confidence in giving the 

 result of ray own observations. 



Since November 1861 I have most carefully searched for Mr. Nas- 

 myth's "willow-leaves" under various circumstances. 



From November 1861 to April 1862 I was engaged in astrono- 

 mical pursuits at Nice, and on every fine day I examined the sun 

 with one of three equatoreals — a 4-inch, a 6-inch, and an 8-inch 

 (belonging to Mr. Coventry), with powers from 40 to 500. In the 

 summer of 1862 I examined the sun at Paris with another 8-inch 

 object-glass of exquisite definition. In November of the same year 

 I revisited Nice; and until my return, in April 1863, I omitted no 

 opportunity of searching for the "willow-leaves," but never have I 

 seen the slightest trace of "willow-leaves," "rice-grains," or 

 " thatch." 



During this spring I have also examined the sun with a small 

 telescope, fitted with a binocular eyepiece belonging to a first-class 

 microscope, and without any greater success, though the spots are 

 clearly shown as funnel-shaped depressions or holes : all that I see 

 on the sun is merely a difference of greater or less luminosity. 



A remark was made at our last meeting that perhaps these ap- 

 pearances depend on focus, and the examination of Diatomaceae out 

 of focus was given as an instance. When I returned home I ex- 

 amined several specimens of Diatomaceae, both easily resolvable and 

 tests (Navicula cuspidata), with various powers of from 3 -inch to a 

 |--inch, in and out of focus ; and I could compare them to nothing 

 but diatoms out of focus ; there was not the least resemblance to 

 anything I have ever seen on the solar disk. — From the Monthly 

 Notices of the Royal Astronomical Society, May 13, 1864. 



ON THE YELLOW COLORATION OE FADED PHOTOGRAPHIC PRINTS. 

 BY M. CAREY LEA. 



Everything connected with the permanence of photographic pro- 

 ducts has an interest so vital to photography, that nothing connected 

 with it can be considered as trivial. We are yet groping in the dark 

 as to the causes of failure. " Sulphuration " is a convenient word, 

 but it would be more satisfactory if we had some idea as to the nature 

 of the obnoxious insoluble sulphur compound. 



The hypothesis which has for some time past become current is, 

 that the fading depends upon the presence in the print of some sul- 

 phur compound, which with time acts upon the silver, converting it, 

 as is said, into sulphide. Sulphide of silver we know as a jet-black 

 substance, and we habitually convert the reduced silver of negatives 

 into sulphide when we wish to intensify them. Why then should 

 the production of sulphide of silver strengthen a negative and de- 

 stroy a print ? 



MM. Davanne and Girard answer as follows. Sulphide of silver 

 prepared by itself is, they say, black ; but formed in presence of 

 organic matter, the organic matter enters into the composition and 

 the compound is yellow. To prove this, they precipitate a solution 

 of silver with sulphuretted hydrogen, and find it violet- black. They 



