Chemistry and Physics. 385 
slowly. When heated in a current of dry chlorine, the metal 
burns with great brilliancy, yielding white crystals of its chloride 
besides a small red sublimate of ferric chloride and a residue of 
undecomposed glucin This reaction indicates the nature of the 
mpurities, and analysis showed that the crude metal contained 
Silica 
Tron 2°08 
Glucina 9°99 
Glucinum 86°94 
\n accurate knowledge of the nature and amount of the impu- 
nities enabled the experimenters to deduce from the observed 
to exist. The specific heat of aluminum multiplied by its atomic 
weight gives the product 0:2143275=5'89, and if we assume 
e 
half that of aluminum, within the limit of uncertainty which still 
attaches to these values, 8 6. TR 
11. Photometric Measurements of Electric Lights.—Mr. W. 
ABNEY uses for this purpose the two shadows of a metal rod 
which 18 lem. in diameter, 7°5 em. long. The shadows are 7-2 
em. distant from one another and are thrown upon a screen 
d 
