PETROLOGICAL ABSTRACTS AND REVIEWS 89 
Wo oskow, A. ‘‘Schmelzversuche tiber Bisilicate mit Sulfiden und 
Halogenverbindungen,” Amznales de [Institute Polytechnique 
Pierre le Grand a@ St. Pétersbourg, XV (1911), 421-42, figs. 6; 
4 photomicrographs. 
The article is in Russian with a two-page résumé in German. Solidi- 
fication curves were studied by means of a Kurnakow self-registering 
pyrometer. The results are as follows: MnSiO;+Mns, eutectic with 
6-85 mol. per cent MnS, 1130° C. BaSiO,+FeS gave rise to a liquation 
of FeS and BaSiO, containing 10 mol. per cent FeS. BaSiO,+ Bas, 
eutectic with 25 mol. per cent BaS, 1325° C. BaSiO,;+BaCl., eutectic 
with 8 mol. per cent BaSiO;, 902° C. Solidification curves of various 
mixtures are given. 
ALBERT D. BROKAW 
Wirinc, E. A. Ueber die Lichtbrechung des Kanadabalsams. 
Sitz. Heidelberger Akad. Wiss., Math.-naturw. Kl., 1911, 20 
Abhandl., pp. 1-26. 
Calkins (Science, XXX [1909], 973), compared the indices of refrac- 
tion of Canada balsam with various minerals in 300 thin sections from 
one to eight years old, and found that in only one case out of a hundred 
did the index of balsam exceed 1.544. ‘The lowest value obtained was 
between 1.535+0.002. He gives 1.54 as a fair mean, and says it 
rarely has an index of less than 1.535 or greater than 1.545. Schaller 
(Am. Jour. Sci., XXTX [1910], 324), with an Abbé-Zeiss reflectometer, 
found that uncooked balsam in sodium light had an index of 1.524, 
soft-cooked an average of 1.5387, as usually cooked an average of 1.5377, 
and over-cooked an average of 1.5412 with a maximum value of 1.543. 
Wiilfing in the fourth edition of Rosenbusch-Wiilfing’s Physiograplie, 
Vol. I, Part I, p. 150, gave the value of the index of balsam as +1.54, 
and in the same volume, Part II, p. 345, said it varied between 1.542 
nearly to 1.550. 
In the present paper Wiilfing gives determinations made by compari- 
son with minerals in thin sections prepared 30 to 4o years ago, and also 
determinations made with an Abbé-Pulfrich total reflectometer which 
had been tested, for weeks previously, for errors. On a collection of 
thin sections prepared by Voigt and Hochgesang 30 years ago the value 
N=1.538=0.002 in the central portions of the slides and at the borders, 
which had become yellow with age, ~=1.5416. On other sections values 
