1 82 Mr. Herschel on certain motions produced in 
32. Strontium , Calcium. These metals, in my experiments 
with the feeble powers used, manifested a remarkable indis- 
position to alloy with mercury. The small quantity of cal- 
cium deposited on an amalgamated negative wire obstructed 
its contact 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 im- 
parted the positive rotatory property sensibly, though very 
feebly. That this was not merely owing to the low conduct- 
ing power of the liquid, was proved by introducing a minute 
quantity of the amalgam of zinc, when the mercury imme- 
diately commenced rotating strongly. The influence of mag- 
nesium 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 direc- 
tion (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 : 1, 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 ’j 00, oooth of the whole, a current radiating to a short dis- 
