the chemical Production and Agency of Electricity . 431 
given it as- fine a point as I could, I inserted it into a capillary 
glass tube; and, after heating the tube, so as to make it adhere 
to the point and cover it in every part, I gradually ground it 
down, till, with a pocket lens, I could discern that the point of 
the gold was exposed. 
The success of this method exceeding my expectations, I 
coated several wires in the same manner, and found, that when 
sparks from the conductors before mentioned were made to pass 
through water, by means of a point so guarded, a spark passing 
to the distance of -§■ of an inch would decompose water, when 
the point exposed did not exceed of an inch in diameter. 
With another point, which I estimated at i1 - t qq , a succession 
of sparks of an inch in length, afforded a current of small 
bubbles of air. 
I have since found, that the same apparatus will decompose 
water, with a wire ~ of an inch diameter, coated in the manner 
7 4-0 7 
before described, if the spark from the prime conductor passes to 
the distance of of an inch of air. 
Exper. 7. In order to try how far the strength of the electric 
spark might be reduced by proportional diminution of the ex- 
tremity of the wire, I passed a solution of gold in aqua regia 
through a capillary tube, and, by heating the tube, expelled the 
acid. There remained a thin film of gold, lining the inner sur- 
face of the tube, which, by melting the tube, was converted into 
a very fine thread of gold, through the substance of the glass. 
When the extremity of this thread was made the medium of 
communication through water, I found that the mere current 
' of electricity would occasion a stream of very small bubbles to 
rise from the extremity of the gold, although the wire, by which 
it communicated with the positive or negative conductor, was 
