'92 On a New Manometer and the Law of the Pressure of Gases. 



fest a smaller blaze (OOIOO volt or less), and a less active germination. 

 Still older seeds, incapable of germination under even the most favourable 

 conditions, manifest still smaller blaze (0*0010 volt or less), and finally 

 none at all, or the small counter-effect due to polarisation (0*0005 volt 

 more or less). 



The series of communications, of which the present communication 

 is the 12th, is as follows : — 



1. " On the Retinal Currents of the Frog's Eye, Excited by Light and Excited 



Electrically," < Roy. Soc. Proc.,' vol. 66, p. 327, March 29, 1900 ; ' Phil. 

 Trans.,' p. 123, 1900. 



2. " Action Electroniotrice de la Substance Yegetale consecutive a, l'Excitation 



Lnmineuse," ' Comptes Rendus de la Societe de Biologie,' p. 342, 

 March 31, 1900. 



3. " The Electrical Effects of Light upon Green Leaves," ' Roy. Soc. Proc.,' 



vol. 67, p. 129, June 14, 1900. 



4. '•' Four Observations concerning the Electrical Effects of Light upon Green 



Leaves," ' Physiol. Soc. Proc.,' June 30, 1900. 



5. ".Le Dernier Signe de Tie," ' Comptes Rendus de l'Acadcmie des Sciences/ 



September 3, 1900. 



G. " On the Excitability of Nerve : its last Sign of Life," ' Proceedings of the 

 Neurological Society,' October 25, 1900 ; " Brain," p. 542. 



7. " The Eyeball as an Electrical Organ," ' Physiol. Soc. Proc.,' November 10, 



1900. 



8. " On the ' Blaze Currents' of the Frog's Eyeball," ' Roy. Soc. Proc.,' vol. 67, 



p. 439, December 6, 1900 ; 1 Phil. Trans.,' 1901. 



9. " The Frog's Skin as an Electrical Organ," ' Physiol. Soc. Proc.,' December 8, 



1900. 



10. " Action Electromotrice des Feuilles Yertes sous lTnfluence des Liunieres 



Rouge, Bleue et Yerte," ' Comptes Rendus de la Societe de Biologie,' 

 December 22, 1900. 



11. " Le Premier Signe de Yie," ' Comptes Rendus de l'Academie des Sciences, 5 



December 24, 1900. 



" On a New Manometer, and on the Law of the Pressure of Gases 

 between 1*5 and O'Ol Millimetres of Mercury. 5 ' By Lord 

 Eayleigh, F.R.S. Received January 15, — Read February 21, 

 1901. 



(Abstract.) 



The new manometer, charged with mercury, is capable of measuring 

 small pressures to an accuracy of 1 /2000 mm. of mercury. This may 

 be compared with the ordinary manometer, read with the aid of a 

 cathetometer, which is capable, according to Amagat, of an accuracy 

 of 1/100 mm. at most. 



With this instrument the behaviour of nitrogen, hydrogen, and 



