March §th, ipi2.] PROCEEDINGS. xxxv 



(i) Palladium is not always in a condition in which it 

 will absorb hydrogen, but it can be made to do so by heating 

 to about 400° C. in either air or in vacuo. The power of 

 picking up gas dies away with time, and cannot be restored 

 unless the metal is reheated. 



(2) Hydrogen is first condensed on the surface of the 

 metal (adsorbed layer) and then gradually diffuses inwards 

 (absorption). It is possible to get the metal either saturated 

 outside and with no gas in the interior, or saturated in the 

 interior and not on the surface. 



(3) Diffusion of hydrogen through the metal begins at 

 about 120* C. and increases in rate with rise of temperature. 

 The same temperature does not, however, always produce 

 the same rate, as it depends somewhat on the state of the 

 metal. The rate does not obey any simple law of diffusion 

 or effusion. 



Ordinary Meeting, March 19th, 1912. 



The President, Professor F. E. Weiss, D.Sc, F.L.S., 

 in the Chair. 



A vote of thanks was given to the donors of the books upon 

 the table. The recent accessions included : " TAe British 

 Tunicata." vol. iii, by J. Alder and A. Hancock, edited by 

 J. Hopkinson (8vo., London, 1912), and "^ Alonograph oj 

 the British Desmidiaceae," vol. iv, by W. West and G. S. West 

 (8vo., London, 19 12), purchased from the Ray Society. 



Professor S. J. Hickson, F.R.S., exhibited a specimen of a 

 recent coral, Endopachys grayi, from the Persian Gulf, and in the 

 course of his remarks upon it pointed out that the Manchester 

 Museum possessed until quite recently three out of the four 

 known specimens of this species. One of these, however, had 



