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itself is in equilibrio with the cohesion of the glass ; and, if this 

 latter were diminished, it would be broken by a charge of less in- 

 tensity. A slip of glass of good quality, one tenth of an inch 

 square, cannot be pulled asunder by less than thirty pounds ; and 

 the cohesion of a square inch of the surface of water is about two 

 grains. I have also found, that a jar, one eighth of an nich thick, 

 cannot bear a charge, which would strike through more than four 

 inches of air; and therefore we may conclude, that, if the particles 

 of glass cohered as weakly as those of water, it would be pierced by 

 a power, which could pass through the ten millioneth of an inch 

 of air. It is therefore probable, that this passage of Voltaic elec- 

 tricity through water is merely a series of spontaneous discharges, 

 facilitated by the separation of its elements. This opinion is con- 

 firmed by many facts. If a feeble power, as of ten pair of plates 

 very weakly charged, be used to decompose it, gas does not ap^ 

 pear instantly on making the connexion. Somethnes more than a 

 second intervenes, and afterwards its evolution is not uniform ; but 

 it makes its appearance in bursts, with very perceptible remis- 

 sions between. If we also consider an observation of Davy, that 

 any bending in the tube between the wires materially impedes 

 the decomposition; and that, if the plates are of moderate size, 

 they afford more of the electric matter than the tube can transmit. 

 And if we add to this the assertion of Cavendish, that water 

 conducts, even in high intensities, 400,000,000 of times worse 

 than iron, we can scarcely suppose it not to insulate such 

 low powers; for low they must be, as a battery ot 2000 pair 

 could only strike through half an inch of a Torricellian vacuum, in 

 which a spark of the common machine would perhaps pervade 

 miles. In a trough of the common construction, I cut off half a 

 zinc plate, and that half of the adjacent copper, which was opposed 



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