W. H. WEEKES, ESQ. 191 



and are united at each end by a joint fusion of the glass and 

 metaL Two other wires of platina proceed from the lower ends 

 of the copper wires to nearly the bottom of the jar, where they 

 terminate in closely-wound spirals, rather more than an inch 

 •part, while the ends of the copper wires, projecting from the 

 upper ends of their respectiye tubes, have conical cavities drilled 

 ■ oat for the reception of a globule of mercury, by means of which 

 communication with the voltaic battery is established. The 

 third tube, passing first to the depth of an inch below the metallic 

 plug, is bent above the latter into a syphon form, and contains in 

 its curvature a globule of mercury weighing about three drachms, 

 which acts as a valve for the occasional escape of gaseous matter 

 generated within the close vessel, and is, at the same time, a 

 guarantee against the ingress of any species of insect life. The 

 mercury employed to form this valve was cautiously distilled 

 firom the red sulpharet of that metal. 



By the side of the close vessel above described was placed, in 

 the first instance, a glass tumbler, capable of holding half a pint 

 of liquid- Through two pieces of mahogany, cemented to oppo- 

 rate inner surfaces of this second vessel, were made to pass two 

 stout copper wires, terminating, like those adapted to the close 

 jar, in platina spirals a little more than an inch apart near the 

 bottom of the tumbler. The upper ends of these wires were 

 similarly provided with longitudinal cavities also, drilled out for 

 the reception of small globules of mercury, to complete contact 

 and facilitate inter-communication. 



On the 3nd of May, 1842, the apparatus, of which a descrip- 

 tion has been attempted, was set to work after the following 

 manner : — A solution of ferrocyanate of potass, prepared by care- 

 fully boiling two ounces of the salt in sixteen ounces of distilled 

 water, being in readiness for the occasion, ten ounces of the 

 liquid were transferred to the glass jar, and immediately after an 

 elastic metal pipe, in communication with an iron bottle in a 

 state of white heat, and from which a stream of pure oxygen 

 rapidly proceeded, was dipped into the solution in the jar. In 



