154 Scientific Intelligence. 
organic substances, their grounds for this assumption being, as we 
have seen, Dulong’s oe deter 2 to - velocity of cooling at 
high temperatures t Dulong and Petit did not carry their in- 
vestigations pr soul besenia the siaenients of boiling mereury ; 
hence their formula relatin ng to high temperatures is mere theory, 
the soundness of which we have now been enabled to test most 
sodas by cern the radiant power of a mass of fused 
tal raised to a temperature of 3,000° F., 30 inches in ie 
qu 
me assumed by Pou a It may be pos itively asserted, more- 
over, that an increase of the dimensions of our radiator to any 
ettetit, laterally or saiesiy. could not augment the intensity or 
the dynamic energy developed by a given area. Again, Dulong’s 
formiila, as applied by omy hay shows that the emissive power of 
a metallic radiator, raised t a temperature of 3,000°, reaches the 
illet 
high temperature of 3,000°, we have only ‘6 ow in a similar 
manner the amount of energy develo apes: by a enetallie radiator of 
low temperature, to be enabled to ip — siden 
made for this purpose with a paratus of different foetal, the ; renalts 
having proved substantially alike. The device most readily de 
scribed keapacte! of a \ spherical vessel charged ~ Lords suspended 
within onstant tempera 
ture. Re seme pee show that, when by “aifferential tempera 
ture is 65°, the enclosure being maintained at 60°, while the § game 
is 125°, the dynamic energy transmitted to the enclosure 
tion is confirmed by the fact that, du uring the summer solstice at 
noon, when the sun’s differential radiant intensity is 65°, the so 
