Chemistry and Physics. 



ternal processes. He calls at 



large number of endothermic re 



in wlii.ii heat is absorbed — and promises a continuation of his i 

 •i.—Annalen der Physih und Chemie, No. 8, 1882, pp. 



2. Absorption of the Electric Light hy the Atmosphere.— Pro- 

 l<-ss..rs Aybton and Perry in using their Dispersion Photometer 

 Iiavi- been struck with the large percentage of absorption of the 

 rays of tin- electric light by the atmosphere. The green rays on 

 <'crtaiii ,];iyv. .j,v absorbed bv :hi atmosp here u li id i appears per- 

 fectly clear to the eye. The photon i. ter employed by them has 

 become simplified and they now use Rumford's method in prefer- 

 ence to other screen methods.— Ph. M. Mag., July, 1882, pp. 45- 



3. Tension of Mrrrnr>i Vapor at h>>r tnnperotores. — The ob- 

 servations of various observers have differed. Those of Regnault 

 have been generally accepted. Herr E. B. Ilagen has made a 

 '•aiviul investigation to reconcile the differences of various ob- 

 servers and is led to the conclusion thai Kegnault's results, which 

 are given ip most text-books, are too great. Hagen gives a table 

 "f comparison between his results and those of Regnault extend- 

 ing from 0° to 100° (for differences of 10°). At 0° Hagen ob- 



till "> "-"l "' and Regnault 0-0200""". At 100° Hagen gives 



0-2I ,nm while Regnault gives 0'7455. — Ann. der Phy&'tk and 



TZ 



of Carbon in Iron and Steel: 

 pothesis of the Hardening of Steel; 



of the different kinds of iron, known 



Undergoes nn being heated to redness and then suddenly cooled 

 by plunging it into water, mercury, or oil, and known as li.mh,,- 

 ">:/ ; also of the peculiar property known as tt i/i/» ring, by which 



After having passed in review the chief properties of the dif- 

 ferent kinds of iron, the paper goes on to discus- the different 

 theories that have been proposed to account for these properties. 



An objection is raised against the different theories which con- 

 sider the iron and carbon as chemically united together, on the 



