1911-12.] Absorption of Light by Inorganic Salts. No. V. 49 
The sulphates were chosen for examination in the case of each of the 
five alkali metals because I wished to examine the effects due to the base, 
and our experience with cobalt sulphate and nickel sulphate showed us 
that the S0 4 exerts no appreciable absorption. It will be seen from the 
table that the absorption in the ultra-violet due to the alkali metals is very 
small, and in some cases it could just be measured. It is confined to the 
end of the range. They appear, however, to have all a band just off* the 
range below 235/x, which was the smallest wave-length I could reach with 
my apparatus. 
The expense of the investigation was defrayed by a grant from the 
Carnegie Trust for the Universities of Scotland. 
{Issued separately March 20 , 1912 .) 
VOL. XXXII. 
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