170 



SCIENCE 



[N. S. Vol. XLVI. No. 1181 



the difference in the total heat of the vapor L be- 

 tween the temperatures T and T — 1 degrees abso- 

 lute, viz., L — Lo and in this case an amount of 

 heat equal to E/T = (L — L„) must be added to 

 maintain the vapor in a saturated condition, and it 

 is therefore called the "negative specific heat" at 

 the temperature T. It L — i is greater than H/T 

 the difference of heat must be added and it is then 

 called "positive specific heat." The examples 

 show that all the numerical values in this respect 

 determined by Clausius on a somewhat different 

 basis agree perfectly with those obtained after the 

 above formula, which agreement, however, is not 

 found with other results obtained by other authors 

 on a similar basis, apparently due to errors of 

 judgment so liable in the application of the cal- 

 culus. Moreover, it is argued that instead of the 

 heat quantity E/T which represents the net work 

 when the expansion takes place in a reversible 

 cycle, the heat quantity We representing the maxi- 

 max work in reversible expansion should be used, 

 which changes the values of positive and negative 

 heat slightly. 



The separation of erbium from yttrium: B. S. 

 Hopkins and Edward Wichers. The erbium- 

 yttrium material used in the investigation was ob- 

 tained by fractional crystallization of the bro- 

 mates. Methods recommended by Drossbach and 

 Wirth could not be duplicated with the success ob- 

 tained by these workers. Cobaltieymide precipita- 

 tion as recommended by James, was found to give 

 a good separation, but offered practical difficulties. 

 Precipitation with sodiimi nitrite as used by Hop- 

 kins and Balke found to give a rapid separation 

 when used with material which was predominantly 

 yttrium. 



A study of the ratio of ErjO^:$ ErCh: C. W. 

 Balke and Edward Wichers. A brief discussion 

 of other ratios used in determining the atomic 

 weights of the rare earth elements was given and 

 the constancy of composition of the rare earth 

 sulphates questioned. The method of applying the 

 oxide-chloride ratio to erbium was described and 

 data given which give an atomic weight approxi- 

 mately one unit higher than the present value. 



A thermal study of some members of the system 

 PbO — SiO^: L. I. Shaw and B. H. Ball. Many 

 mixtures of PbO and SiO, varying in composition 

 from 40 per cent, to 90 per cent. PbO were melted 

 in an electric furnace and the records of their 

 thermal conduct plotted on time-temperature dia- 

 grams. (In some cases PbO, was used instead of 

 PbO and its behavior is noted.) The significant 

 temperatures of these graphs were then combined 



into a composite temperature and it was concluded 

 that the system is a case of solids in solid solution. 

 Two maxima corresponding to the composition 

 PbO — SiOj and 2 PbO — SiO^ were found and 

 another 2 PBO — 5 SiO, was clearly indicated. 

 Two eutectics are indicated, though the lower one 

 may be a transition point of the one of the higher 

 melting point. As noted by previous investiga- 

 tors, a transition point of SiO, was found at 540°- 

 580° C. All mixes sintered at 690° ± 10° C. 



A study of tlie change of conductivity with time 

 in the system methyl alcohol-iodine-water: L. I. 

 Shaw and John P. Trickey. Conductivities of 

 solutions of iodine in methyl alcohol of various 

 boiling points have been measured. It was found 

 that the conductivity increased much more rapidly 

 in the ease of the solutions in alcohol of higher 

 boiling points; also, that the conductivity reached 

 a higher value in the case of the solutions from the 

 higher boiling point alcohols. It was suggested 

 that this was probably due to the water content of 

 the alcohol. It was found that a smooth curve 

 could be drawn through the points at which the 

 conductivity of the various solutions became con- 

 stant. Suggestions as to the probable reaction 

 were given. 



The solubility of pure radium sulfate: S. C. 

 Lind, C. P. Whittemore and J. E. Underwood. 

 The solubility of EaSO, in water and other solu- 

 tions is of practical interest since all processes for 

 the recovery of radium from its ores involve, at 

 some stage, the precipitation of radium together 

 with barium as sulfate. 



Stiidies in pseudo-isotopy — Part I: S. C. Lind. 

 Experiments of the author and others have shown 

 that when radium and barium are partially precipi- 

 tated from a solution containing a mixture of the 

 two, no change in relative concentration takes 

 place. This is true for sulfate, oxolate, carbonate, 

 and perhaps all other dilfieulty soluble salts, and 

 bears an exact analogy to the inseparability of the 

 isotopic elements. The fact that radium and 

 barium are only, pseudo-isoto'pia, however, is shown 

 from the great divergence of their atomic num- 

 bers, and their ready separation by reorystalliza- 

 tion of the chlorides or bromides. It has been 

 shown in the preceding paper that the assumption 

 of identical solubility of RaSOj and BaSO, in 

 analogy to their pseudo-isotopic action in precipi- 

 tation reactions, is far from the truth. Conversely, 

 this must raise the question, from the purely ex- 

 perimental side, as to the truth of the assumption 

 generally made of identical solubility of true iso- 

 topes. 



