556 S. Taber — Grdwih of Crystals. 



soluble, and go easily into solution where subjected to pressure 

 by a growing- body. 



The writer believes that the forces developed during crystal 

 growth have played an exceedingly important part in the 

 formation of many veins. In an earlier publication some of 

 these veins were described in detail and many of the facts sup- 

 porting this hypothesis were given,"" but additional evidence is 

 now available. A paper is at present under preparation in 

 which the experimental data so far established, together with 

 such observational data as have been collected, will be used in 

 attempting to explain various geologic phenomena, especially 

 the formation of veins. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Stannous and Lead Double Halogen Salts. — E. Rtmbach 

 and K. Fleck have prepared a number of these double chlorides 

 and bromides. They are ammonium and potassium salts with the 

 exception of one rubidium compound. The investigation appears 

 to have been carried out systematically and skillfully, so that all 

 the salts that could be crystallized from aqueous solution were 

 generally obtained. The following salts with lower ratios of 

 alkaline halide to bivalent halide were obtained : 



1:2 2:1 



RbPb„Cl 6 (NH 4 )„SnCI 4 .H 2 



K 2 SnCl 4 .H s O 

 1 : : K;SnCl 4 .2H 2 



NH 4 SnCl v H o (NH 4 )„SnBr 4 .H 2 



KSnCl s .H o 0" K 2 SnBr 4 .H„0 



NH 4 SnBi V H 2 

 KSnB. v H,0 

 KPbCl 3 



All of the above salts were previously known, and all of the tin 

 compounds had been described in 1892 by Richardson who 

 worked at Johns Hopkins University under the direction of Pro- 

 fessor Remsen. Richardson was unable to prepare any 4 : 1 salts 

 corresponding to (NH 4 ) 1 SnCl 6 .3H 2 and K 4 SnCl fi .3H 2 0, which had 

 been described by Poggiale in 1842, but in the investigation 

 under consideration four of these tin salts were produced, as well 

 as a corresponding lead salt: 



* Taber, S., Geology of the Gold Belt in the James River Basin, Virginia, 

 Va. Geo!. Surv., Bull. No. VII, pp. 222-231, 1913. 



