46 MR. DANIELL ON VOLTAIC COMBINATIONS. 



gested by the experiments with the entire sphere ; although I cannot vouch for the 

 comparative measures being absolutely correct or uninfluenced, in some degree, from 

 day to day by extraneous circumstances, and particularly by changes of temperature : 

 nor can it, indeed, be expected that the experimental deductions from a ball of the 

 dimensions which I employed can do more than approximate to the mathematical 

 demonstrations of the relations of an active point within an attractive sphere. 



An accidental circumstance next furnished me with an interesting variation in the 

 combination of the whole sphere. My intention had been to fill it as before, and re- 

 peat the experiments ; but I afterwards found that the liquid only reached to within 

 45° from the vertex. The zinc ball which I made use of was J inch in diameter, 

 and the membrane was full of the dilute acid. The experiments were made in three 

 different positions of the ball, and with three variations of the wire connecting the 

 circuit with the brass sphere. 



The first connexion was made near the top at a point which was not within the 

 contact of the included liquid ; the results were 



Caloric Galv. 



o 



At the top 45 



Centre 55 



Bottom 65 



Connexion with the bottom of sphere. 



Ball at the top 45 



Ball at the centre 70 



Ball at the bottom 11 



Connexion with the sphere both at the top and bottom. 



o 



Ball at the top 45 



Ball at the centre ..... 73 

 Ball at the bottom , . . . . T% 



The two last series may be taken to be identical, but I am at a loss to explain the 

 difference of the first series from these two. It is probable that the zinc ball, though 

 wholly immersed in the acid in the membrane, was not below the surface of the ex- 

 terior solution in the sphere. The results confirtn in a general way the conclusions 

 which have been previously suggested. 



There was yet another combination which I thought it desirable to try ; namely, 

 with the generating ball placed within the charged sphere with its two hemispheres 

 insulated. The zinc ball which I employed for this experiment was one inch dia- 

 meter, and I tried it first with the standard acid with which all the other experi- 

 ments had been made, and repeated it with the same acid diluted with an equal bulk 

 of water, in order that I might ascertain whether the law of action were influenced 

 at all by the amount of force put into circulation. The results were perfectly con- 

 sistent with each other. 



