Minutes of Proceedings. xxxi 
the law y = X - 7 holds for all the phthaleins, the constant 7 representing 
the molecular volume of HoSOj^. 
" Colour and Chemical Constitution. Part YII : Inorganic Phenomena 
in Connection with Cobalt, Nickel, Manganese and Uranium." By James 
MoiE. 
" Colour and Chemical Constitution. Part YIII : Fluorescence and its 
Laws." By James Moie. 
On comparison of the spectra of dissolved (ionised) salts of these metals 
with those of the salts in the solid state, " loading " effects are observed 
similar to those shown by the phthaleins. The formation of blue cobalt 
compounds is ascribed to considerable increase of molecular weight due to 
cembination with environing molecules. In the case of cobalt halides the 
wave-lengths appear to be proportional to the eighth root of the molecular 
weight, and in uranyl compounds they are proportional to the sixth root. 
The coincidence of these numbers with the periodic place of the element is 
noted. 
Solid uranyl compounds fluoresce, and the emission-spectrum shows 4 or 
5 bands which are the absorption-bands of the same substances moved up 
from the blue into the green. The general law == 0']45 A f expresses the 
change of wave-length from absorption to fluorescence-emission ; thus an 
absorption-band at A 499 in any of these solid fluorescent substances is 
accompanied by a fluorescent band at a 574, which agrees with the above 
formula. This relationship between cube of fluorescent wave-length and 
fourth-power of absorption wave-length appears to hold for other fluorescent 
substances as well as for uranium compounds. 
Q 
