224 Mr. H. E. Durham. On the Special Action of [Jan. 23, 



with many metals, and carbonic oxide especially with iron. Whether 

 this condition is rightly distinguished from ordinary chemical com- 

 bination is a question which admits of debate. The stability of all 

 dissociable compounds is influenced by pressure and by temperature 

 in the same kind of way as " occlusion," which, like ordinary chemical 

 combination again, is a phenomenon in which the bodies concerned 

 exercise a power of selection. 



The presence of hydrogen as well as carbon dioxide in gra/nite, 

 if already observed, is not known to geologists generally. From 

 observation on variations in the critical point of carbon dioxide in 

 minerals (' J. Chem. Soc.,' 1876, ii, 248), Hartley seems to infer that 

 the incondensable gas present with carbon dioxide, is usually nitro- 

 gen. A passage in Geikie's ' Text Book of Geology,' third edition, 

 p. 110, refers to the presence of hydrogen in cavities ; but at present 

 I have no information as to the evidence upon which this state- 

 ment is based. The presence of hydrogen in such a rock . as 

 granite must be attributed to the existence of this gas in large 

 proportion in the atmosphere in which the rock was crystallised. 

 Whether this was the primeval atmosphere of the earth before the 

 hydrogen had escaped or had been oxidised into water, or whether it 

 resulted from the local action of water upon unoxidised metals or 

 other materials in the interior of the earth, is a question which 

 may be of some interest to the geologist. If the former hypothesis 

 were adopted, it would perhaps be difficult to explain the absence 

 of helium from the gas included in the rock; and, on the whole, 

 I incline to the latter view, as affording the more probable ex- 

 planation. 



I have ascertained that hydrogen is present in even larger pro- 

 portion in the granite from the neighbourhood of Dublin, and I 

 propose to examine some other examples of the ancient crystalline 

 rocks in order to determine the nature of the gases enclosed in them. 



II , "Ona Special Action of the Serum of Highly Immunised 

 Animals, and its Use for Diagnostic and other Purposes." 

 By Herbert E. Durham, Gull Research Student in Patho- 

 logy. Communicated by Dr. Sherrington, F.R.S. Received 

 January 3, 1896. 



(Abstract.) 



The following conclusions are the outcome of an enquiry into the 

 nature and value of " Pfeiffer's reaction," which was made at the 

 suggestion and uader the guidance of Professor Max Gruber, of 

 Vienua, to whom my best thanks are due. The present communica- 



