QuirTce and FinTcelstein — Radioactivity of Meteorites. 237 



Art. XIX. — Measurements of the Radioactivity of Meteo- 

 rites ; by Terence T. Quirke and Leo Finkelstein. 



Although the determinations of the radioactivity of various 

 rocks are now numerous, the radioactivity of meteorites is 

 known for only two varieties of meteorites and for only three 

 meteorites. The meteorites examined were tested by Strutt* 

 His results are : — 



Locality Material Variety Quantity Ea per gm. 



Taken material 



Dhurmsala Stony Met. Intermed. 50 gm 1-I2xl0"'^gm 



Chondrite 

 Thunda Iron Met. Medium 60 



Octahedrite 

 Staunton " " " 32 



Augusta Co. Ya. 



Santa Catarina, Iron 50 



Brazil 

 Disco Island, Native Iron 200 0*424 X lO"'" gra 



Of these materials Santa Catarina is generally accepted to be 

 terrestrial iron and not a meteorite. Our information in regard 

 to the radioactivity of meteorites could be summarized as 

 follows ; one intermediate chondrite, a stony meteorite, has a 

 radium content of 1'12X10~''^ gm, Ra. per gm. meteorite, and 

 two medium octahedrites, iron meteorites, are free of radio- 

 activity. 



Through the generosity of Dr. Oliver C. Farrington of the 

 Field Museum of Natural History, the authors had the follow- 

 ing varieties of meteorites placed at their disposal : — fifteen 

 aerolites, or stony meteorites, one chladnite, two eukrites, two 

 white chondrites, one carbonaceous chondrite, one black chon- 

 drite, three spherulitic chondrites, three spherulitic crystalline 

 chondrites, one crystalline chondrite, two siderolites or stony- 

 iron meteorites, live iron meteorites, one finest octahedrite, 

 two medium octahedrites, one coarse octahedrite, and one nor- 

 mal hexahedrite. 



Chemical Preparation of the Materials 



The iron meteorites were dissolved in hot cone. HCl and 

 HNO3 in a platinum dish. All the stony and stony-iron 

 meteorites were treated consistently. Stony meteorites differ 

 from igneous rocks in that most of them contain a considerable 

 amount of metallic iron and nickel. Each sample was ground 

 *Strutt, Proc. Eoy. Soc , A, Ixxvii, p. 480, Mar. 1916. 



