206 H. C. Bolton—Action of Light on Uranium. 
small speck of perchlorate of potassium was added to the acid- 
ated mixture of starch and iodid. 
January, 1869, 
action of nitric acid and chlorate of potassium, and that the 
arsenic acid thus formed may be precipitated without incon- 
venience in the form of arseniate of magnesium and ammonium. 
Boston, May 20, 1869. 
Art. XXII.—On the Action of Light on Uranium; by H. 
Carrineton Boiron, Ph.D. 
Compounps of uranium were found to be sensitive to the 
sun’s rays at a very early period in the history of the element. 
Klaproth, who discovered uranium in 1789, makés no allusion 
to the property in question, but Bucholz in 1805 remarked the 
effect of light on solutions of the sulphate and nitrate. Since 
Bucholz’s discovery seems to have escaped the observation of 
most chemists, I may be allowed to quote from his communi- 
pda rl ac a in the “ Annales de Chimie et de Physique,” 
D 
Bucholz remarks in another paragraph: “Nitrate of uranium 
is very soluble in ether, and the yellow solution exposed to the 
sun’s rays becomes green, an odor of nitric ether is developed, 
and a black substance is precipitated.” Chemists added little 
to these facts for many years ; Gehlen observed that the oxy- 
chlorid was sensitive to the light, when in a solution contain- 
ing alcohol ; Berzelius states, in his “ Lehrbuch,” that the pre- 
cipitate formed in the solution of the sulphate is a basic proto- 
salt, and adds that the precipitate produced by the reduction 
_ of the nitrate has not been examined. 
_ In 1841, Ebelmen* made a complete investigation of the 
decomposition of the oxalate of the sesquioxyd, He writes 12 
* Ann. Ch. Pharm., xliii, 286. 
pea ci ea a eee PSE ie ee Oe RN ne ey i a SR a a cea rie 
