NOTES. 191 



experiments in cultivating these bacilli on agar, bouillon, and 

 gelatine mixed with urine, which had been suggested to him by 

 the presence of B. colt in the bladder. On these media the 

 microbe grew luxuriantly, forming greyish colonies ; the B. typhi 

 abd. less rapidly in fine transparent patches. In the discussion 

 Eisner said there were plenty of differential signs ; the difficulty 

 was to cultivate Eberth's bacillus when it was only present in small 

 number — for instance, in water, or mixed with other bacteria, for 

 example, in stools. Ewald, Wolf, and Senator, all had found 

 Eisner's method very useful for the diagnosis of doubtful cases 

 from the stools. — Brit. Med. Journ. 



IRotee. 



Helium. — From the results of the experiments recorded in 

 this paper, it seems that helium exists in the minerals in which it 

 is found in a condition comparable with that in which hydrogen is 

 associated with many metals, and carbonic oxide especially with 

 iron. Whether this condition is rightly distinguished from ordinary 

 chemical combination is a question which admits of debate. The 

 stability of all dissociable compounds is infiuenced 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 granite, 

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

 observation on variations in the critical point of carbon dioxide in 

 minerals (Journ. Chem. Soc.^ 1876, II., 248), Hartley seems to infer 

 that the incondensable gas present with carbon dioxide is usually 

 nitrogen. A passage in Geikie's Text-Book of Geologv, 3rd edit., 

 p. no, refers to the presence of hydrogen in cavities; but no 

 information is given as to the evidence upon which this statement 

 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 



