Marcu 15, 1912] 
if the wire becomes thin in one spot the tendency 
to burn out is much less than it would be with the 
wire run in vacuo. It is therefore possible to 
make reliable measurements of the candle power 
at a temperature much closer to the melting point 
than is possible in vacuo. The results were: in 
hydrogen 3250° K., 3345°, 3430° and one some- 
what doubtful value of 3500°; in mereury vapor, 
3450° K. and 3350°. As the method tends to give 
low results it is highly probable that the melting 
point of tungsten is at least 3500° K. or about 
3250° C. This is in good agreement with the 
value given by Pirani 3300° C., but very different 
from that of yon Wartenberg, who gave 2900° C. 
JOEL H. HILDEBRAND: 
of Barium Peroxide. 
This equilibrium has been investigated on ac- 
count, not only of its scientific interest, but be- 
cause of its practical application in the manufac- 
ture of oxygen and hydrogen peroxide. 
The nature of the phases involved was deter- 
mined by observing the effect upon pressure of 
removing successive portions of oxygen, the tem- 
perature being kept constant. It was shown that 
within certain limits the oxide and peroxide form 
solid solutions in each other, and that a barium 
hydroxide phase must also be present. Conditions 
for reversing the equilibrium were stated. 
Accurate measurements of the dissociation pres- 
sures of the univariant system were made, and the 
thermodynamics of the system discussed. 
The Thermal Dissociation 
S. C. Linp: Chemical Combination and Disintegra- 
tion under the Influence of Radium. 
Chemical action produced by radium is due 
almost entirely to the a-rays. For gas reactions 
both of combination and of disintegration the 
number of molecules affected in a given time is 
of the same order of magnitude as the number of 
tons formed by the a-rays in that time, as caleu- 
lated from Bragg’s experiment on the ionization 
of gases. Data of Ramsay and of the author 
verify this conclusion with respect to radium 
emanation. A method is proposed for calculating 
simply the mean path of a-rays in cylindrical and 
spherical vessels. The principle found true for 
gases may also be extended to liquid systems, data 
of Ramsay, of Debierne, and of the author being 
used for its establishment both for emanation and 
radium salt in solution. 
Eucene C. BineHam: Fluidity and Vapor Pres- 
sure. 
E. C. BrincHam and G. F. WHITE: Fluidity and 
Hydration. 
SCIENCE 
429 
E. C. BrneHaM and G. F. WHITE: A New Viscosi- 
meter. 
EDWARD C. FRANKLIN: Potassium Ammono Thal- 
late. 
When the ammono base, potassium amide, in 
solution in liquid ammonia is added to a solution 
of thallium nitrate in the same solvent a black 
precipitate of thallium nitride is formed in accord- 
ance with the equation, 
3TINO, + 3KNH, = TI,N + 3KNO, + 2N4H,. 
Thallium nitride dissolves in a liquid ammonia 
solution of potassium amide to a clear yellow 
solution from which potassium ammono thallate of 
the composition represented by the formula, 
TINK, . 4NH;, may be obtained in the form of 
beautiful yellow crystals. The action of potas- 
sium amide on thallium nitride is represented by 
the equation, 
TIN + 6KNH, = 3TINK, . 4NH, + 2NH,. 
WILLIAM BLtuM: The Hydrolysis of Sodium Ox- 
alate and its Influence upon the Test for Neu- 
trality. 
The testing of sodium 
a primary standard 
oxalate for use as 
in acidimetry and oxid- 
imetry requires a knowledge of the normal 
alkalinity. Decimolar solutions of pure sodium 
oxalate were found to produce a pink color with 
phenolphthalein equivalent to 4 per cent. trans- 
formation of the indicator, instead of the eal- 
culated 8 per cent., showing discrepancies in the 
accepted constants or theories. Colorimetric com- 
parisons were made with solutions calculated from 
Sorensen’s E.M.F. measurements, indicating that 
for 0.1 m Na,C,0,, [H*},,0 ——2 oe One mand enbat 
the salt is hydrolyzed to the extent of 0.0024 per 
cent. The error produced in a titration by neg- 
lecting this normal alkalinity is negligible. 
R. C. Wetus: The Fractional Precipitation of 
Hydroxides. 
By fractionally precipitating dilute solutions of 
various pairs of metallic salts with caustic soda 
the following series was obtained, such that the 
higher members are more precipitable: ferricum, 
aluminum copper, zine, lead, nickel, silver, fer- 
rosum, manganese, magnesium, calcium. The posi- 
tion of a metal in the series is probably deter- 
mined by (1) the solubility of the hydroxide and 
(2) the extent of hydrolysis of the metallic salt. 
The series agrees well with the order of the heats 
of precipitation of the hydroxides. 
C. W. HAsLEY and B. F. Brann: 
Weight of Mercury. 
The Atomic 
