482 Scientific Intelligence. 



c 



l=^[logJ/+log(.'^*^"-l)] (3) 



When c/Ai® is very large the last equation reduces to 



i^i+^logi-^ (3) 



This amounts to using Wien's law instead of Planck's. 



7. Numerical Application: Solar Radiation. — To obtain an 

 approximate idea of the order of magnitude of the effects formu- 

 lated the author considers the sun as being a black body at 

 6000° absolute. The receiving body is assumed spherical 

 (7;=: 4) and the apparent diameter of the sun is taken as 32'', 

 so that log M = 12.1 c = 14,350 micron X degree. Under 

 these conditions equations (1), (2), and (3) lead to the follow- 

 ing results: 



K 



T 



Ai 



T 



OAfjL 



1980°abs 



5/x 



250° 



0.5 



1700° 



10 



130° 



1 



1000° 



black body 



280° 



2 



550° 







It is thus seen that a spherical body having a single absorption 

 band in the violet would attain a temperature approximately 

 equal to the melting point of platinum, when exposed to radia- 

 tion like that which is emitted by the sun and reaches the outer 

 limit of the earth 's atmosphere. This remarkable result is easily 

 explained qualitatively by considering the fact that the body 

 in question can only exchange energy under the form of violet 

 radiation; for, this radiation commences to be emitted to an 

 appreciable extent only at a very high temperature. Until then 

 the sphere absorbs energy without emitting any, and thus its 

 temperature rises. In conclusion it should be remarked that the 

 author touches upon the question of the temperature of space 

 and also gives a tentative explanation of the enhanced brilliancy 

 of comets ' tails when near the sun. — Jr. de Phys., v, 207 ; May- 

 June, 1916. H. s. u. 



8. Colored Flames of High Luminosity. — A by-product of 

 an investigation, by G. A. Hemsalech, on the spectrum of iron 

 was the invention of an assemblage of apparatus which produces 

 flames very intense in color and hence especially suitable for 

 lecture demonstrations. The apparatus comprises four essen- 

 tial parts, which are, the sprayer, the collector, the mixing 

 chamber, and the burner. 



The sprayer is made of an ordinary glass tumbler the upper 

 open end of which is fitted with a wooden cover sealed in place 



