392 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Ueber die physikalisch-chemishen Beziehungen zwischen 

 Aragonit unci Calcit. — The object of this investigation by H. W. 

 Foote was to show by purely physiochemical methods: 1. 

 which of the two minerals under the existing conditions of tem- 

 perature and pressure is the more stable ; 2. whether the tem- 

 perature of transformation is higher or lower than ordinary tem- 

 perature. The method of investigation consisted in determining 

 the relative solubility of the two minerals at different tempera- 

 tures, as it is known on theoretical grounds that the least soluble 

 must be the more stable. The best results were obtained by 

 determining the electrical conductivity of aqueous solutions satu- 

 rated with calcite or aragonite and carbon dioxide at atmospheric 

 pressure and varying temperatures. It was found that calcite is 

 more stable than aragonite at the temperatures experimented 

 with, and that the solubility curves approach each other as the 

 temperature rises. The author believes, however, from his own 

 results and those of others, that at atmospheric pressure, calcite, 

 below its melting point, can never become the less stable of the 

 two minerals. From this it is concluded that the paramorphism 

 of calcite after aragonite is theoretically possible, and the opposite 

 paramorphism impossible. It is the author's opinion that rapid- 

 ity of crystallization is one of the causes of the formation of ara- 

 gonite. — Zeitschr. physikal. Chern., xxxiii, 740. h. l. w. 



2. Atomic Weight of Radio- Active Barium. — It is well 

 known that M. and Mdme. Curie have discovered a substance 

 "Radium" which is found with the barium of pitch-blende. By 

 systematic fractional crystallization of the barium chloride ob- 

 tained from the mineral, more concentrated products have been 

 obtained. Finally by partial precipitation of solutions of the latter 

 by means of alcohol or hydrochloric acid the concentration has been 

 carried still further. The last product made in this way was 

 examined spectroscopically by Demarcay and found to contain 

 apparently only a trace of barium. This result indicates the iso- 

 lation of radium chloride, but the quantity of the product was 

 too small for use in an atomic weight determination. For the 

 latter purpose Mdme. Curie was therefore obliged to use a less 

 pure materia], in which, from the aspect of its spectrum Demar- 

 cay thought that there was more radium than barium. Her re- 

 sults in two determinations gave the numbers 174*1 and 173*6 for 

 the atomic weight of the metal in this chloride. Since the 

 atomic weight of barium is 137*5, radium should have an atomic 

 weight much higher than 174. The valency of radium is not dis- 

 cussed, but it is evident that if this is greater than that of 

 barium the indicated atomic weight would be much lai'ger. — 



Comptes Rendus, cxxxi, No. 6. h. l. w. 



