1824.] Conductors when transmitting the Electric Current. 277 



indeed, that a complete insolubility of the amalgam in pure mer- 

 cury may be the cause of this want of action, but the supposition 

 must be allowed to be uvery forced one. 



31. Barium. — This metallic body amalgamates with the 

 utmost readiness with a power of eight pairs of plates when the 

 muriate is acted on ; a small globule of mercury at the negative 

 wire throwing out beautiful arborescences, and fixing into a 

 highly crystalline, pretty permanent, solid amalgam. A very 

 minute quantity of this introduced into mercury under solution 

 of soda, gives it the positive property. Its efficacy, in reversing 

 the direction of the currents, is strikingly sensible when intro- 

 duced into a quantity of mercury kept in a state of negative 

 rotation under oxalic acid. The amalgam of mercury and barium 

 added in small quantities to pure mercury, imparts to it the same 

 property as we noticed in the case of sodium, of forming a Vol- 

 taic combination with a wire brought in contact with it under 

 a saline solution, and the action so produced is much more 

 lasting. 



32. Strontium, Calcium.— These metals, in my experiments 

 with the feeble powers used, manifested a remarkable indisposi- 

 tion to alloy with mercury. The small quantity of calcium 

 deposited on an amalgamated negative wire obstructed its con- 

 tact with a larger globule of mercury to such a degree, that no 

 electric communication could be established. Under a solution 

 of strontia, the contact of the negative wire imparted the posi- 

 tive rotatory property sensibly, though very feebly. That this 

 was not merely owing to the low conducting power of the liquid, 

 was proved by introducing a minute quantity of the amalgam of 

 zinc, when the mercury immediately commenced rotating 

 strongly. The influence of magnesium is more sensible than 

 that of strontium or calcium, from the greater readiness with 

 which it amalgamates. 



33. Zinc. — When pure mercury is electrified under solutions 

 of potash or soda, with neither pole in contact, in the manner so 

 often alluded to, it shows no signs of rotation, as has already 

 been observed ; but, if touched for an instant with the end of a 

 clean zinc wire, or if an atom of the solid amalgam of zinc, the 

 smallest that can be taken up on the end of a needle, be added 

 to it, it instantly rotates violently in a positive direction (or from 

 the positive pole). 



34. An alloy of one part zinc to 10,000 of pure mercury 

 rotates with the utmost violence. When this is diluted with 

 ten times its quantity of the latter metal, the force of rotation 

 appears but little impaired. The proportion of mercury was 

 increased to 400,000 : J, and the rotation, though feeble, was 

 yet complete, pervading the whole of a considerable mass of 

 the alloy ; and even when the zinc amounted to no more than 

 a 700,000th of the whole, a current radiating to a short distance 



