gager: effect of radium rays on plant life 159 



greater than is contained in the quantity of radioactive manure 

 commonly recommended for application to an acre." 



Ramsay^ has recently calculated that in order to double the 

 amount of radioactive gas (emanation) in the soil "one must use 

 about 75 milligrams of radium per acre at a cost of $7,500." This 

 amount is somewhat more than the possible increase in value of 

 any crop per acre, however stimulated, yet a less amount of 

 emanation would quite certainly be too weak to produce any 

 appreciable physiological effect. 



Hopkins and Sachs^ carried on extensive and careful experi- 

 ments for two years with the radioactive fertilizer prepared by 

 the Standard Chemical Company, of Pittsburgh (the same 

 preparation that was used by Dean Rusby). Their final con- 

 clusion is as follows: 



"Thus from the two years' work we have six trustworthy 

 average results with corn, three 'for' and three 'against' radium, 

 and we have eighteen averages with soy beans, nine 'for' and 

 nine 'against' radium. In all of these trials the average vari- 

 ation from the checks is so slight and so evenly distributed 'for' 

 and 'against,' as to lead only to the conclusion that radium 

 applied at a cost of $1, $10 or $100 per acre has produced no 

 effect upon the crop yields either the first or the second season." 



The authors further point to the fact that to apply the radio- 

 active preparation to the soil in the amounts recommended by 

 Fabre would, at present market values, cost nearly $59,000 per 

 acre. To say the least, the results of various investigators seem 

 rather conflicting. 



About two years ago the writer was presented with ten pounds 

 of a "radioactive" fertilizer, called B.D.R., by representatives of 

 the Radium Bank {Banque du Radium), of Paris, and was re- 

 quested to test its virtues for agriculture. Numerous experiments 

 were carried out, some closely following the directions given by 

 the representatives of the Radium Bank, and some according to 

 suggestions obtained from three years of experience in testing the 

 effects of radioactivity on plants. It is not necessary here to go 

 into details, but only to state that the net results of the tests were 

 absolutely negative. 



1 Science n. 42: 219. 1915. 



2 Science H. 41: 732-735- I9i5- 



