Geology an d Min eralogy. 511 



This is a condensed report of the investigations in this region by 

 the author and other members of the Survey covering several 

 years. The map is on the scale of 4 miles to 1 inch ; and the 

 formations represented include Laurentian, Huronian, Cambro- 

 Silurian and Silurian of Niagara-Clinton age. h. s. w. 



10. Le Granite des Pyrenees et ses phenomenes de contact ; by 

 A. Laceoix (Bull, des serv. carte geol. de France, No. 64, pp. 68, 

 pi. 3, 1898). — In this interesting work Professor Lacroix confines 

 himself to discussing the details of observation on the contacts 

 in the vicinity of Haute Arriege. The facts, which are given in 

 considerable detail, lead him to believe that where the granite has 

 come in contact with schists, these latter have been enriched in 

 feldspar by transference of material from the granite and con- 

 verted largely into gneisses; where calcareous rocks have been 

 altered, it has been of the more usual type already well known 

 and previously described with formation of various lime-bearing 

 silicates. The endomorpbic modification suffered by the granite 

 when in contact with the calcareous beds, is its transformation 

 into basic types, generally diorite, sometimes norite and even peri- 

 dotite in border zones at the contact. This is believed to be 

 caused by enrichment in basic oxides due to the melting up and 

 absorption of masses of the calcareous beds. Attention is also 

 drawn to the importance of mineralizing gases and vapors in the 

 contact area, which the author thinks have not been sufficiently 

 taken into account by previous investigators. He thinks that the 

 action produced by deeply buried granite magmas is of quite dif- 

 ferent character from that effected by those more nearly approach- 

 ing the surface, as those for instance in the Christiania region. 



l. v. p. 



1 1. Igneous Rocks of Tasmania ; by W. H. Twelvetrees and 

 W. F. Petterd. (Trans. Australasian Inst, Min. Eng., vol. v, 

 No. 62, 1898.) — Although this account is very short and confined 

 mostly to general statement, it is none the less welcome in giving 

 petrographers some notion of the rocks occurring in a hitherto 

 little known region. Granites, felsites, augite-syenite, trachyte 

 andesites, gabbro, basalt, diabase, limburgite, minette and perido- 

 tites are among the various types briefly mentioned. l. v. p. 



12. On Sidphohalite. — In the course of a series of investigations 

 of the phenomena of salt-bed formation, J. H. van't Hoff and A. 

 P. Saunders attempted to obtain an artificial salt corresponding 

 to the composition, 3Na 2 S0 4 . 2NaCl, given by Hidden and 

 Machintosh for sulphohalite. With this end in view solutions 

 containing sodium chloride and sodium sulphate were evaporated 

 at the extreme temperatures of 25° and 70° centigrade. In the 

 presence of a sufficient quantity of sodium chloride, the sulphate 

 crystallized out, even at the lower of these temperatures, without 

 water of crystallization, i. e. as thenardite. Thus, at both 25° 

 and 70° the authors obtained well-formed cubes of sodium chloride, 

 free from sulphate, and rhombic pyramids of thenardite free from 

 chlorine. The double salt, however, was not formed, though its 



