394 Geological Society : — 



being proportional to each other, so that the results of his theory 

 are not inconsistent with the ordinary kinetic theory of gases. 



J. L. H. 



Anleitung zur miJcrochemischen Analyse organischer Verbindungen. 

 By H. Beheens. Part IV. Leipsic : Voss, 1897. 



A previous volume of this work on the investigation by means of 

 the microscope of aromatic amines was noticed some months ago ; 

 the present work relates to uric acid and urea and their derivatives, 

 and the more important organic acids. J. L. H. 



LIV. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from p. 815.] 



February 24th, 1897.— Dr. Henry Hicks, F.R.S., President, 

 in the Chair. 



THE following communications were read : — 

 1. ' On the Nature and Origin of the Rauenthal Serpentine/ 

 By Miss Catherine A. Raisin, B.Sc. 



This serpentine has been already described by Herr Weigand as 

 one of those which occur in regions of gneiss or schist related in 

 their origin to these rocks. In order to test this hypothesis as to 

 the formation of the serpentine, the author has examined the 

 district and has studied its rocks with the microscope. 



Herr Weigand asserted that transitions could be recognized from 

 typical gneiss to a peculiar amphibolite, and that the latter rock has 

 been changed to serpentine. The author could find in the field no 

 evidence of a passage from gneiss to amphibolite, and calls attention 

 to the general difficulty of the supposition. She states that when 

 the serpentine is examined microscopically, the greater part shows 

 the usual appearance of serpentine derived from olivine, and can be 

 distinguished from included parts, which have resulted from change 

 in hornblende or other pyroxenic constituents. Further, that 

 several accessory minerals occur which are usually found in 

 peridotites. The rock also contains a peculiar chlorite. This 

 she thinks the result of the modification of a biotite, for the latter 

 mineral occasionally occurs as a constituent in a neighbouring 

 serpentine, and, both there and in the Rauenthal, forms appa- 

 rently intermediate can be detected. It seems to her that the 

 chemical analyses already published are not in harmony with the 

 supposed change of a hornblende-rock into serpentine. 



While it is true that a hand-specimen sometimes shows a trans- 

 ition (generally rapid) from a rock consisting mainly of hornblende 



