74 Uoyal Society .—Messrs, J. H, Gladstone and k. Tribe on 



tively, the gas being collected and measured at the end of 24 or 48 

 hours. The quantity of gas in cubic centimetres is given in the third 

 and fourth columns of the subjoined Table, corrected for temperature 

 and pressure. The mean temperature in the second column is simply 

 the mean of the maximum and minimum during the period. In ex- 

 periment A, 33*4 grms. of zinc-foil v/ere employed, being 2*6 metres 

 long and O'Oo v/ide. The coils were kept apart by muslin. la 

 experiment B there was used 1 metre of similar foil crumpled up. 



Day. 



Mean 

 temp. 



Exper. A. 



Exper. B. 



Day. 



Mean 

 temp. 



Exper. A. 



Exper. B. 





C. 



c. c. 



c. c. 





C. 



c. c. 



c. c. 



1. 



12-8° 



117-1 



49-6 



18. 



6-7° 



20:0 



7-6 



2. 



12-2 



93-8 



37-5 



19, 20. 



6-1 



17-2 (X 2) 



5-7 (X 2) 



3. 



11-7 



73-8 



27-6 



21. 



4-4 



20-0 



6-6 



4. 



11-1 



66-2 



24-7 



22. 



50 



15-3 



4-8 



5,6. 



10-0 



49-3 (X 2) 



17-5 (x2) 



Interval. 









7. 



8-9 



41-1 



14-9 



44. 



10-0 



20-5 



5-5 



8. 



10-5 



40-9 



15-8 



1 45,46. 



10-5 



22-5 (X 2) 



6-5 (X 2) 



9. 



10-0 



40-9 



14-8 



47. 



11-1 



22-3 



6-5 



10. 



7-8 



33-8 



10-3 



48. 



11-1 



24-1 



8-1 



11. 



6-7 



28-0 



9-4 



49. 



11-1 



20-5 



7-4 



13, 13. 



6-1 



21-9 (X2) 



7-7 (X2) 



Interval 









14. 



6-1 



20-1 



7-6 



82. 



10-0 



18-0 



4-7 



15. 



7-2 



31-1 



10-3 



83. 



10-0 



18-9 



61 



16. 



100 



30-0 



10-2 



84. 



10-0 



14-0 



5-1 



17. 



8-3 



29-4 



8-5 











The two experiments have evidently gone on almost pari passu 

 for months, the amount of hydrogen evolved gradually diminishing, 

 but showing, at the same time, a certain dependence on the heat of 

 the day. 



Under the microscope the bubbles of gas are seen to form, not on 

 the zinc, but among the copper crystals, and sometimes to make their 

 appearance on the glass at some distance off. 



From the position of platinum in the electro-chemical series we 

 anticipated that the effect would be still more marked with that 

 metal in a spongy state on the zinc. It was deposited from the 

 tetrachloride, and, of course, thoroughly washed. There was only 

 0*6 metre of foil ; but the following quantities of hydrogen were ob- 

 tained ; — 



Day. 



Mean temp. 



Yol. in cub- centims. 



1. 



11-7° C. 



143-6 



2. 



11-4 



93-6 



3,4. 



10-0 



38-8 (X 2) 



5. 



8-6 



26-0 



6. 



10-8 



21-0 



7. 



9-4 



17-1 



8. 



7-7 



12-3 



