The London, Edinburgh and Dublin philosophical magazine and journal of science . ces the inversionof the positions of argon and potassium. As regards boron, gallium, and indium, the radiation ofthese elements in a magnetic field has not been the other hand, there is no room for doubt as regards theline-pairs corresponding to aluminium and thallium. Thesame applies to the alkali group, where only the two yellowsodium lines have been investigated in a magnetic field. In fig. 2 is represented the same relation for Mg, Ca, Sr,Ba, and Ra. The extrapolation gives for the atomic weigh
The London, Edinburgh and Dublin philosophical magazine and journal of science . ces the inversionof the positions of argon and potassium. As regards boron, gallium, and indium, the radiation ofthese elements in a magnetic field has not been the other hand, there is no room for doubt as regards theline-pairs corresponding to aluminium and thallium. Thesame applies to the alkali group, where only the two yellowsodium lines have been investigated in a magnetic field. In fig. 2 is represented the same relation for Mg, Ca, Sr,Ba, and Ra. The extrapolation gives for the atomic weightof radium the value 258. Of course, the straight line maybe to some extent rotated and displaced without any greatdeparture from the points ; but the figure shows clearly thatthe value 225 as determined by Madame Curie is considerablyremoved from the straight line. In the following table the straight line is represented by aformula, and the extrapolated value obtained by calculation. -480 The Position of Radium in the Periodic System., Fia- % 2,5n 7fa accorc?77iQfoyfrne Cunt. J,0 3,5 *.o Logarithm of line-distance (#01 scale-division= 2-8 per cent.). I£ x stands for the width of the line-pair, measured on thescale of frequency 108/^, then we have :— Calculated atomic weight=antilog.(•2005 + ? 5997 log x). Observedatomic weight. 23-84 24-36 Ca ... 40-6 40-1 Sr ... 87-5 87-6 Ba ... 136-9 1374 The extrapolation for radium gives for its calculated atomicweight the value 257*8. We do not venture to suppose that our value deservesmore confidence than that determined by Mine. Curie. Itmust, however, be remarked that in view of the close re-lationship of barium and radium, and the small quantitieswith which the chemist is forced to work, the complete sepa-ration of these two bodies is very difficult, and that if theseparation had been incomplete Mine. Curie would havefound too small a value for the atomic weight. Accordingto the crystallographic observations of F. R
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