CHEMISTRY: RICHARDS, CRAIG AND SAMESHIMA 
387 
common lead nitrate and 1.7991 for uraniolead nitrate. The outcome of this 
work, then, by rinding no appreciable difference in the molal solubility of the 
different samples of lead nitrate containing isotopes of widely different atomic 
weights, confirms earlier work upon other properties of these interesting sub- 
stances. Evidently weight (or mass) is the prime distinguishing feature of 
the two kinds of lead here studied, as it was in other cases. This work and that 
described in the preceding section thus afford further support for the hy- 
pothesis due to Russell, Fleck, Soddy and Fajans. 
1 This paper and the two following are taken from an abbreviated version of a report to 
. the Carnegie Institution of Washington (which generously subsidized the investigations) 
presented in August, 1918. 
2 Richards and Yngve, /. Amer. Ckem. Soc, Easton, Pa., 40, 1918, (164). 
THE PURIFICATION BY SUBLIMATION AND THE ANALYSIS 
OF GALLIUM CHLORIDE 
By Theodore W. Richards, W. M. Craig, and J. Sameshima 
WOLCOTT GlBBS MEMORIAL LABORATORY, HARVARD UNIVERSITY 
Communicated, October 31, 1918 
A new method for the purification of gallium salts was worked out in some 
detail. This rests upon the convenient fact that gallium trichloride sublimes 
and distils at a low temperature, whereas the other chlorides likely to be 
associated with it are much less volatile. The method rested, therefore, 
upon fractional distillation and sublimation, at first in a stream of chlorine 
and afterwards in a vacuum, of impure gallium chloride. 1 The apparatus 
was a complex affair, in which gallium could be first burned in pure dry chlorine 
and then subjected to distillation either first in pure chlorine, then in nitro- 
gen, and finally in a vacuum, the whole apparatus being fused together without 
rubber connections and scrupulously dried. In order to avoid the use even 
of ground joints (with their attendant alternative danger of leakage or con- 
tamination from lubricant) the gas connections were opened by means of 
sealed magnetic hammers acting on enclosed capillaries, and closed by fusion 
of the glass connections. The gallium was provided through the great kind- 
ness of Mr. F. G. McCutcheon of the Bartlesville Zinc Company, Blackwell, 
Oklahoma, to whom grateful thanks are due. Three successive distillations 
of the trichloride of gallium were made in chlorine at 220° to 230°C, three 
more at about 175° (the melting point of gallium dichloride), three in nitrogen 
at 90° to 110°, and five sublimations in vacuo at 65° to 80° — fourteen in all. 
Distillation in nitrogen or in vacuo is needful to eliminate dissolved chlorine. 
The resulting product showed no trace of any other substance in its spark 
spectrum when examined with great care in a Hilger wave length spectrom- 
eter. Although this study did not reach a final stage, and much more 
