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LXXVII. The Radioactive Properties of High Temperature 

 Flames. By H. Carter, A.R.C.Sc, B.Sc, Royal College 

 of Science, London*. 



Object of the Experiments. 



THERE is at the present time no well-authenticated case 

 where radioactivity is called into existence by any 

 artificial process. All the known phenomena in this branch 

 of science are due to the spontaneous atomic disintegration 

 observed in the naturally active substances. 



If such an atomic disintegration can, under any circum- 

 stances, be set going artificially, it seems likely that this 

 would occur in cases where large quantities of energy are 

 being set free in a small volume. Such cases are those of 

 the electric arc, the spark, and the oxyhydrogen and oxy- 

 acetylene blowpipe flames. 



It is practically impossible to test with any great refine- 

 ment for the emission of a radiation in any of these processes, 

 on account of the enormous ionization of non-radioactive 

 origin already present. Very searching tests can, however, 

 be made for $ radiation, which may be looked for at a 

 convenient distance from the place where energy is being 

 dissipated. Such tests form the subject of the present paper. 



General Descrijrtion. 



A gold-leaf electroscope was used throughout the tests, 

 the method of procedure, stated very generally, being to 

 compare the rate of leak of the electroscope when under the 

 inHuence of the source with the rate of leak obtained when 

 the electroscope was shielded from the action of the source. 



The cases investigated were the electric arc, the oxy- 

 hydrogen and oxyacetylene blowpipe flames, and the electric 

 spark. 



The chief difficulties encountered w r ere, practically speaking, 

 common to all the cases, and were : heating of the electro- 

 scope by the source, causing temperature variations through- 

 out a test, the presence of ionized air near the electroscope, 

 and, in the case of the spark, choice of a suitable cover for 

 the electroscope. 



The arrangement of the electroscope is shown in the 

 diagram attached (fig. 1), and this is, to a large extent, self- 

 explanatory. 



* Communicated by the Hon. Pt. J. Strutt, F.R.S. 



