March 7, 1919] 



SCIENCE 



227 



RADIUM PRODUCTION 



During the period of the war, with no camo- 

 tite exports, the greatest part of the world's 

 radium supply has been produced in the United 

 States. The following table shows the radium 

 output of the Standard Chemical Company of 

 Pittsburgh, Pa., since 1913, at which time 

 radium was first produced in the United 

 States. 



Rjidlura 

 ElemeDt, 

 Grams 



1913 2.1 



1914 9.6 



1915 1.7 



1916 5.0 



1917 7.0 



1918 13.6 



39^0 



It is estimated that the total radium pro- 

 duction in the United States to 1919 approxi- 

 mates 55 grams of radium element, and this 

 represents, probably, more than half of all the 

 radium produced in the world. 



There has been some discussion lately by 

 members of the Bureau of Mines as to the 

 amount of radium that can be produced from 

 the camotite fields, as well as suggestions that 

 mesothorium, a by-product from monazite, 

 should replace radium in the luminous mate- 

 rial which has found extensive use in the war 

 on airplane and ship instrument dials, com- 

 passes, and many indicating devices, and 

 which will find extensive use on watches and 

 clocks, etc. 



The estimates of Dr. Moore, of the Bureau 

 of Mines, are based on a very inadequate 

 study of the camotite region made prior to 

 the war and before the fields had been de- 

 veloped to any great extent. The carnotite 

 holdings of the Standard Chemical Company, 

 which are the largest under the control of a 

 single company or individual and comprising 

 about 350 claims, have been carefully studied 

 — in part by systematic diamond drilling — and 

 this work has been the basis for an estimate 

 that at the least 500 grams of radium should 

 be produced from camotite. This is five times 

 greater than Dr. Moore's estimate. 



As regards mesothorium as a radium sub- 



stitute, there are several points whose im- 

 portance Dr. Moore and the Bureau of Mines 

 have overlooked or minimized, in their anxi- 

 ety to conserve radimn. Statistics show that 

 before the war considerably less than one 

 thousand tons of monazite was worked up in 

 the United States per annum in the pro- 

 duction of thorium nitrate, and it is estimated 

 that about three thousand tons of monazite 

 supply the world's needs for thorium nitrate. 

 Each ton of monazite containing about 5 per 

 cent, of thoria (corresponding to good Brazil- 

 ian concentrates) will yield about two milli- 

 grams of commercial mesothorium, so that per 

 annum there may be expected a world's meso- 

 thorium production of about six grams. The 

 cost of producing monazite will always pre- 

 vent the production of mesothorium except as 

 a by-product. Unlike radium, which has a 

 half-decay period of 1,700 years and can be 

 used in luminous material immediately after 

 refining and for medical purposes after thirty 

 days' aging, mesothorium has a comparatively 

 brief half-decay period of 5.5 years and its 

 economical use in luminous compound is only 

 possible a year or t^vo after refining'. For 

 medical purposes, the short life and varying 

 gamma ray activity of mesothorium make this 

 product less desirable than radium. The fol- 

 lowing table given by McCoy and Cartledge'^ 

 shows the change in gamma-ray activity of pure 

 mesothorium in time, due to the gradual decay 

 of mesothoriiun I. (the parent product) and 

 the increase and decrease of radiothorium, 

 which produces thorium D with its very pene- 

 trating gamma rays. 



THE CBLiNGE OP GAMMA BAT ACTIVITT OP MESO- 

 THOKrUM WITH TIME 



Time In Years 



Total 



1.000 

 1.370 

 1.558 

 1.620 

 1.604 

 1.538 

 1.442 

 1.334 

 1.219 

 1.107 

 1.998 



1 Jour. Am. Chem. Soc, XLI., 53, January, 1919. 



