422 Experiments in Voltaic Electricity. 



water to the Voltaic action, and obtained at the negative pole, 

 where the mercury was jilaced, an amalgam of that metal and 

 hydrogen, which was not given off in tlie form of gas; I thought 

 it wortli while to repeat the experiment, which I have varied in 

 everv possible way, and of which the following is an accmate 

 account. — if you think it worth whil' to make room for it among 

 the more important communications \ou are in the habit of re- 

 ceiving. Having let fall a globule of pure mercuiy of about 

 twice the size of a pea into a watch-glass of common spring 

 water, I plunged two platiua wires, proceeding from each end of 

 a Voltaic trough, into the water, neither of them tonchir.g the 

 globule, but removed to tlie opposite extremities of the glass. — 

 Oxygen and hydrogen were given out by each as usual, the mer- 

 cury remaining unaltered ; the wires being brought nearer, the 

 niercurv lost its globular form, extending itself in an oval shape, 

 much flattened, appearing equally attracted by each wire. The 

 wires being both made to touch the globule and drawn back 

 again, the mercury adhered to the negative. In this situation, 

 the positive wire not touching the metal, no hvdrogen gas was 

 given out by the negative, or so small a quantity that it required 

 very minute inspection to detect it : the mercury apjjeared of less 

 specific gravitv, more fluid and brilliant than before ; whilst the 

 positive wire separated a copious stream of oxygen. In two or 

 three minutes some bubbles of hydrogen began to arise, but in 

 imall quantity. 



If the positive wire is brought within a small distance of the 

 mercury when connected with the negative, a great portion of 

 the oxygen passes over the surface of the globule and of the 

 water in a rapid current towards the negative wire ; and oji 

 bringing it almost in contact, the mercury is attracted by it, 

 touches it, and immediately shrinks from it, assuming the form 

 of a cone, and again expanding so as to touch the wire a se- 

 cond time, continuing this motion or rather pulsation for some 

 time. When the trough is first charged, this motion is iricon- 

 ceivably rapid, and has continued with a single two-inch trough 

 of oO plates for two hours or more. The negative wire will be 

 found coated with mercury on being removed. If the positive 

 Avire is plunged into the globule (the negative not touching it), 

 and even drawn out of it immediately, it becomes fixed in a 

 moment, losing its brilliancy and fluidity, depositing a black 

 oxide at first, and after some hours a beautifiil lemon-coloured 

 oxide ; but it does not become less fluid after remaining in 

 this situation a week than it does after a few seconds. No 

 oxygen is given out by the positive wire at first ; but after some 

 seconds, when the globule appears a good deal oxided, a few 

 bubbles begin to appear, while the negative wire gives out a 



copious 



