Chemistry and Physics. 575 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Rate of Production of Helium from Radium. — Sir James 

 Dewae having succeeded, by the use of the radiometer, in 

 detecting a gas pressure of the fifty-millionth of an atmosphere, 

 and having definitely detected by this means the helium pro- 

 duced in a few hours from about ten milligrams of radium 

 bromide, has undertaken the direct measurement of the helium 

 produced by radium. For this purpose he employed 70 mg. of 

 radium bromide belonging to the Royal Society, which had been 

 used by Dr. Thorpe in his recent determination of the atomic 

 weight of radium. The apparatus employed for measuring the 

 helium consisted of a McCleod gauge in which no rubber joints 

 were used, together with ingenious arrangements for exhausting 

 the apparatus. Any traces of adventitious gases were absorbed 

 by an attached bulb containing charcoal and cooled in liquid air. 

 In one instance the pressure registered at the start of the experi- 

 ment was 0*000044 mm. The radium salt was occasionally heated 

 and the pressure of the helium was determined from time to time. 

 A steadily maintained helium increment was obtained of approx- 

 imately 0*37 cu. mm. per gram of radium per day. This result 

 agrees very closely with Rutherford's theoretical calculation, 

 which gives about 0*3 cubic millimeters per day. — Advance 

 sheets from author. h. l. w. 



2. Radium in Tufa Deposits. — Schlundt has examined a 

 number of these deposits from Hot Springs, Ark., and finds that 

 the amount of radium in them varies to a remarkable degree. 

 Some of the samples gave low results corresponding to 0*56, 0*72, 

 0-73, 1-18, 2-62 and 2-85 x 10 -12 g. of radium per gram of tufa, 

 while other samples gave such results as 26*7, 36*3, 156*0, 227, 

 1322 and 1900 X 10 -12 g. of radium. These deposits appear to 

 be derived from springs of similar character, and differences in 

 the physical character of the material gave no clue to their 

 radium contents. Boltwood had previously found considerable 

 variations in the radium in the water from different springs in 

 this locality, and it appears from a limited correlation of the 

 results that no correspondence exists between the radium contents 

 of the waters and of the tufas deposited by them. — Chem. JVews, 

 xcviii, 199. h. l. w. 



3. A Compound of Cobalt zoith Carbon Monoxide. — Mond, 

 Hirtz arid Cowap have succeeded in preparing cobalt carbonyl, 

 Co(CO) 4 , which corresponds in composition to the remarkable 

 nickel compound described by Mond and other co-workers in 

 1890. The cobalt compound was prepared by taking advantage 

 of a method of Dewar for facilitating the formation of nickel 



