1861.] 



223 



central pool of mercury and separates the 

 supernatant electrolyte into two equal por- 

 tions, and causes the central portion of 

 mercury to form two connected pools, and 

 to act as a cathode on one side and as an 

 anode on the other, the polar wires being 

 immersed in the outer pools. The sounds 

 and crispations were more definite with 



narrow strips of mercury -|-th of an inch wide than with wider ones, 

 and with annular ones than with circular or rectangular pools : the 

 annular strip may be of any moderate diameter ; the best width of 

 mercury to give a definite sound is about y^th of an inch, because 

 there is then only room for two rows of moderate-sized elevations ; 

 when the rows are numerous, as in a circular or rectangular pool, the 

 vibrations (and the sounds) are frequently irregular, and interfere 

 with each other. On several occasions fine white sand was sprinkled 

 upon variously shaped negative surfaces of vibrating mercury, but no 

 signs of nodal points were detected. The liquid state of the cathode 

 appeared to be essential, as no sounds were produced on substituting 

 a fine stretched platinum wire for the negative mercury. The anode 

 nearly always contracts, and the cathode lengthens during the elec- 

 trolysis, as may be easily verified by employing segments of rings of 

 mercury for the electrodes. 



15. To ascertain the influence of the chemical nature of the cathode, 

 the glass vessel, fig. 2, open at its lower end, was placed in an outer 



Fig. 7. 



vessel A, fig. 7, and portions of Dr. 

 Wood's fusible alloy, composed of 1*5 

 part cadmium, 2 parts tin, 4 parts lead, 

 and 7*5 parts bismuth, were placed in 

 the central cavity and in the annular 

 space ; the vessels were then filled about 

 one inch deep, in one experiment with a 

 filtered mixture of 1 ounce of hydrocyanic 



acid, -5- an ounce of water, and 25 grains of hydrate of potash ; and 

 in another experiment with 1 ounce of hydrochloric acid, 1 ounce of 

 water, and 30 grains of chloride of potassium, and the liquid heated 

 by means of a sand-bath to about 180 F. to liquefy the alloy* ; 

 * I found by experiment that this alloy solidified at 150 0> 8 F., and in solidifying 



