326 Scientific Intelligence. 



5. Method for the Determination of Carbon in Steel. — As a 

 solvent for steel when carbon is to be determined, G. W. Sargent 

 recommends the use of potassium ferric chloride, since it has the 

 advantage of being less strongly colored than the usual reagent, 

 potassium cupric chloride. A solution containing 26 7 g of com- 

 mercial, chemically pure ferric chloride and 130 # 7 g of potassium 

 chloride in a liter is equivalent to the cupric solution commonly 

 used. It should contain l cc of free hydrochloric acid in 225 cc in 

 order to prevent the formation of basic ferric salts, but a greater 

 quantity of acid than this is liable to cause the evolution of 

 hydrogen and hydrocarbons. The reaction corresponds to the 

 equation, 



2FeCl 3 + Fe = 3FeCl 2 . 



The liquid which has been used can be brought to its original 

 condition by chlorinating and adding the proper amount of potas- 

 sium chloride. — Jour. Amer. Chem. Soc, xxiv, 1076. h. l. w. 



6. Physical Chemistry for Physicians and Biologists ; by Dr. 

 Ernst Cohen. Authorized Translation by Martin H. Fischer, 

 M.D. 8vo, pp. 343. New York, 1903. Henry Holt and Com- 

 pany. — This book is made up of fifteen lectures by a physical 

 chemist, which serve as a satisfactory introduction to the subject 

 in general, and which deal especially with the application of this 

 science to medical and biological problems. The topics discussed 

 are well chosen, the explanations are clear and satisfactory, and 

 it is believed that the book will be very interesting and useful to 

 those for whom it is intended. h. l. w. . 



7. The Bunsen Flame of Radium. — F. Giesel has shown that 

 a very small amount of radium bromide gives a characteristic 

 color to the Bunsen flame. He describes the spectrum as one 

 consisting of two red bands and a bright blue line. He also saw 

 feeble lines in the violet. C. Runge and J. Precht have investi- 

 gated this spectrum with the aid of a Rowland grating of one 

 meter radius. They found the spectral lines very transitory. 

 The line in the blue at wave length 4826 remained the longest. 

 It seemed of the same character as the barium line 5536 ; the 

 strontium line 4607, and the calcium line 4226. A table of wave 

 lengths is appended to their article. — Ann. der Physik, No. 3, 

 1903, pp. 655-657. J. T. 



8. Interference of light by means of a Plane-parallel Plate. — 

 O. Lummer and E. Gehrcke discuss the various methods in 

 interference spectroscopy and describe a method which resem- 

 bles Michelson's echelon spectroscope ; but which the authors 

 think is simpler. It consists in the use of only one plane parallel 

 plate. The method shows that many lines considered as consist- 

 ing of a few components are far more complicated than has gen- 

 erally been supposed. The authors remark that Michelson's 

 value for the red cadmium line A = 643,847 cannot be considered 

 a definite wave length measured to the given decimal place ; nor 

 a certain mean wave length of a continuous region ; it is rather 

 the center of gravity, so to speak, of a complicated system of 



