Electro-deposited Antimony. 449 



30. At the suggestion of Mr. Faraday, aud with the kind 

 assistance of him and Dr. Tyndall, I have been enabled to reduce 

 pieces of the metal of moderate tiiickness (y\jth of an inch) to a 

 state of fine division without exciting the change or destroying 

 the thermic property, by carefully triturating them in a mixture 

 of broken ice and salt. Pieces of the thickness of an address- 

 card were reduced to powder without the change occurring, by 

 careful pulverization in water at 60° F. ; the most ready plan 

 adopted was by gently pressing the pieces in small quantity, 

 under water, in a mortar, with a rolling motion of the pestle (not 

 by blows or rubbing) until they attained the size of a pin's head, 

 listening all the time to detect molecular changes, then inducing 

 the particles to complete powder by gentle rubbing. 



31. By placing small quantities of the dried active powder 

 upon thin sheets of metal and gradually applying heat until the 

 change occurred, sufficient heat was evolved by the molecular 

 force to commence oxidation, which spread at a much lower 

 speed throughout the mass, producing true combustion, and 

 raising it to a temperature of dull redness visible in daylight. 

 The molecular change in the powder is attended by a visible 

 commotion amongst the particles. Portions of the gray variety 

 reduced to powder and treated similarly, exhibited the same 

 combustion. 



32. It would appear from these experiments that amorphous 

 antimony is susceptible of three different, distinct, and indepen- 

 dent changes : — 1st, the cohesive change of its mass, consisting 

 of extensive fractures and bending ; 2nd, the peculiar change, 

 attended by evolution of heat ; and 3rd, a chemical change, con- 

 sisting of oxidation and true combustion ; whilst the crystalline 

 variety is susceptible of only two of these changes. Antimony, 

 deposited in the state of a black powder upon a small cathode, 

 by rapid action in the solution of tartar-emetic and chloride of 

 antimony, exhibited no perceptible change of the second kind, 

 but manifested ra])id combustion by application of heat; and 

 similarly with antimony powder deposited from a solution of 

 antimonic oxide in pyrophosphate of soda. Deposits of metal, 

 obtained from solutions of tersulphide of antimony in caustic 

 potash, exhibited the phfcnomcnon of unequal cohesion, but not 

 the peculiar change. Fused terchloride of antimony, free from 

 water, with an anode of antimony and cathode of copper, did not 

 conduct, even in a small degree, the electric current from five 

 pairs of zinc and silver batteries. By rotating a horizontal sil- 

 vered disc of thin brass. If inch diameter, in the solution of 

 tartar-emetic and chloride of antimony, at a speed of 3500 revo- 

 lutions per minute for thirty-three minutes, and .simultaneously 

 passing a current from five zinc and silver batteries through it 



Phil. May. S. 4. Vol. IG. No, 100. Dec. 1858. 2 G 



