284 Intelligence and Miscellaneous Articles. 



back and sets continuously very near its position of rest. A small 

 but perfectly uniform stream of minute gas-bubbles still ascends 

 from the kathode, but the anode is covered with a thick bubble of 

 gas, and this only escapes every 10 to 20 seconds. As it escapes, 

 the current momentarily increases a little, and again decreases in 

 proportion as the neve bubble forms. In this condition the resist- 

 ance of the voltameter is of enormous magnitude ; but its polari- 

 zation does not exceed that obtained by introducing a large rheostat- 

 resistance, or by filling the voltameter with 40 to 45 per cent, acid ; 

 it is only the resistance, and not the polarization, of the volta- 

 meter which is of abnormal magnitude. On the other hand, in 

 what has been described above as the middle condition, both the 

 polarization and the resistance are of abnormal magnitude, the 

 former too large and the latter too small. I will, however, remark 

 that this middle condition is the less easy to obtain, the nearer 

 the concentration of the acid is to 60 per cent. The first condition 

 passes quickly into the third when the resistance of the rheostat 

 is diminished. 



PHOTOGKAPHY OF THE SOLAE SPECTRUM. 

 To the Editors of the Philosophical Magazine and Journal. 



Survey of India Offices, Calcutta, 

 Gentlemen, January 7th, 1889. 



With reference to the very interesting article on " Photo- 

 graphy of the Least Kefrangible Portion of the Solar Spectrum," 

 by J. C. B. Burbank, which appears in your Journal for October 

 last, will you kindly permit me to point out that my early 

 results in photographing the lines on the less refrangible side of A, 

 which the author attributes to the use of turmeric, were for the most 

 part obtained on collodio-bromide plates stained with a hlue dye, 

 (ordinary aniline blue), the lines in this part of the spectrum being 

 reversed, i.e. dark, on a clear ground. I found, however, at the same 

 time that some collodio-bromide plates, stained with the tincture of 

 the seeds of the annatto plant {Bixa orellana), not turmeric, were 

 unusually sensitive to the whole spectrum, so that I obtained the 

 spectrum up to A and traces of a line below it unreversed. Apart 

 from the reversing, the best results were secured with the blue-stained 

 plates. An account of these experiments was published in the 

 Proceedings of the Eoyal Society, No. 166 of 1876. 



I may take this opportunity of recommending the treatment of 

 cyanin proposed by Messrs. Wellington and Burbank. Plates 

 stained with the dye so treated are exceedingly sensitive in the red, 

 and work much cleaner than if stained with the ordinary cyanin. 

 On Wratten and Wainwright's ordinary plates so treated, I have 

 obtained very good small photos of the spectrum from C to A, but, 

 although there is a considerable extension of action below A, there 

 are only just traces of lines. 



I remain. Yours truly, 

 J. Wateehouse, Lieut.-Col. B.S.C. 



