CHAPTER TX 



EFFECTS OF A RADIOACTIVE ATMOSPHERE ON 

 PLANT GROWTH 



The fact, pointed out in Chapter II, that the earth's atmosphere 

 normally contains the emanation of radium and possibly of other 

 radioactive substances, makes it desirable to ascertain the effect of this 

 factor of environment on plants. Such an experiment was rendered 



Fig. 28. Experiment 40. Apparatus for growing Plants in an Atmosphere con- 

 taining the Emanation of Radium. The inner Surface of the Tube ( T) is coated 

 with Lieber's Radium Coating. From the lower Tubulures of the Bell-Jars Rubber 

 Tubing leads to a Suction Pump. Control Apparatus at the right. Cf . figure 30. \ jj 



comparatively easy by the invention by Mr. Hugo Lieber of a cyl- 

 inder lined with a coating of a radium salt, and covered by a protect- 

 ing layer of such a nature as to permit of the diffusion of the emana- 

 tion into the surrounding space, as described more fully on page 81 



146 



