I^IE. G. GOEE ON THE PEOPEETIES OE ELECTEO-DEPOSITED ANTIMONY. 329 
wrapped in oil-silk and immersed in water at' 60° Fahr. ; the chloride-of-calcium solu- 
tion was now heated to 212° Fahr. in 35 minutes ; a gradually increasing deflection, 
amounting at its maximum to 42^ degrees, occurred, the discharged bar being thermo- 
electro-positive to the active one ; the temperatures were maintained during 2 hours and 
40 minutes, during which time the deflection decreased to 38|- degrees. A second similar 
experiment was made with a pair of bars like the last, one of them being wholly active, 
and the other previously made inactive at one end only, viz. the end most distant from 
the galvanometer, by gradual discharge in boiling water during 30 minutes. With one 
end of this compound bar in water at 50° Fahr., and the other in boiling water, a deflec- 
tion of 28 degrees occurred, the discharged end being thermo-electro-positive to the 
active end of the adjoining bar. A similar experiment with a single active bar of the 
above angular shape, with its ends dipping into two vessels of water, one at 57° and the 
other at 212° Fahr., and connected with the galvanometer by silver wires, gave a -deflec- 
tion of 42^ degrees, which decreased to 40 degrees in 1 hour and 25 minutes. 
117. In numerous experiments the suddenly and also the gradually discharged sub- 
stance was found in every instance to be decidedly electro-positive to undischarged 
portions of the same pieces in the following liquids — pure sulphuric, hydrochloric, or 
nitric acids, freely diluted with water ; also in aqueous solutions of ammonia, sesqui- 
carbonate of ammonia, hydrate of potash, and carbonate of soda. 
118. A bar of the unchanged substance placed axially in a copper wire helix, the 
ends of which w’ere connected with a galvanometer, on having its heat suddenly dis- 
charged by contact of a heated wire with one of its extremities excited no appreciable 
electric current in the wire. 
Comparison of the three varieties. 
119. They each require a solution containing an excess of free acid in addition to the 
amount necessary to dissolve the teroxide, the proportion of free acid necessary being 
greatest with the chloride and least with the iodide. 
120. The rate of deposition admissible to obtain a firm deposit, and also the range of 
speed of deposition, is greatest in the chloride and least in the iodide solution ; being 
about 0’5 to lO’O grains per square inch per hour in the chloride, 3 to 5 grains in the 
bromide, and 0‘5 grain or less in the iodide. The tendency to the evolution of hydro- 
gen gas at the cathode is least in the chloride and greatest in the iodide ; this tendency 
frequently causes the iodide deposit to be completely disintegrated. 
121. Each of the deposits exhibits the phenomenon of unequal cohesion and crack- 
ing (17.), but that formed in the chloride solution exhibits it the most strongly. The 
metal obtained from the iodide solution is the most friable, and that from the chloride 
the least so. The chloride compound is the most metallic in appearance, and the iodide 
one the least. The specific gravities of the three varieties are also in series ; that of the 
chloride deposit is 5'8, the bromide one 5'44, and the iodide one 5'25. 
122. They each possess the power of evolving heat, and this quality appears at 
