42 Wells, Wheeler and Penfield — Alkali-Metal 



further and more exact information. But even if we assume 

 that the lake-beds are Cretaceous, there remains a sufficient 

 argument for restricting the scope of the term Laramie in the 

 fact that to include the two or three series of deposits, with 

 the long intervals between them, under one group name would 

 make the latter unduly comprehensive and important in the 

 scale of Cretaceous sub-divisions." 



Art. IV. — On the Alkali-Metal Pentahalides ; by H. L. 

 Wells and H. L. Wheeler With their Crystallograjthy; 

 by S. L. Penfield. 



Lsr the course of our investigations on the alkaline triha- 

 lides,f the compounds CsCl . CI J, KbCl . C1 8 I and KC1 . C1 3 I 

 were encountered. The potassium compound had been de- 

 scribed many years ago by Filhol.;}; This investigator pre- 

 pared also the body ^H 4 C1 . C1 3 I and obtained a similar mag- 

 nesium compound, probably MgCl 2 . 2C1 3 I . 5H 2 0. He failed 

 in his attempts to make analogous compounds with sodium and 

 a considerable number of the other common metals. 



It was evident from the peculiar behavior of caesium tri bro- 

 mide and triiodide, mention of which was made in one of our 

 previous articles,§ that a still higher bromide and iodide 

 existed. These have now been identified as pentahalides. 



In addition to these bodies we have prepared the sodium 

 and lithium analogues of Filhol's salt. They differ from all 

 the other polyhalides that we have studied in containing water 

 of crystallization. 



A large number of other alkaline pentahalides are theoreti- 

 cally possible, but, although we have made numerous experi- 

 ments with the view of making the most promising of these, 



* Canadian geologists have long recognized several important divisions in 

 what they have called the Laramie. As their divisions cannot be accurately cor- 

 related as yet with those in the United States, owing to the very meagre infor- 

 mation conceruiug the great complex of supposed Laramie strata in Montana, the 

 writer has avoided a consideration of those points in this paper. It seems not 

 unlikely that the divisions of the group made on combined stratigraphical and 

 paleontological grounds in Canada will agree with those to be reached finally in 

 this country. The " Edmonton " and " St. Mary River " beds seem to correspond 

 to the Laramie proper, and the " Paskapoo " and " Porcupine Hills " beds to the 

 Fort Union, but it is less clear that their '-Willow Creek " or Middle Laramie of 

 certain areas is equivalent to the post-Laramie lake-beds here described. " The 

 uplifting of the Rock Mountains " is said by Mr. J. B. Tyrrell to have taken place 

 "at the close of the Edmonton period." (Report on a part of Northern Alberta, 

 p. 137, Ann. Rep. Geol. and Nat. Hist. Survey of Canada for 1886). 



f This Journal, III, xliii, 11 and 475. 



t J. Pharm., xxv (1839), 431. 



§ This Journal, III, xliii. pp. 24 and 27. 



