192 ELECTROLYSIS. 



DEPOSITION OF ANTIMONY. 



The galvanic deposition of antimony having been specially 

 studied by Mr. Gore, we will borrow from him the description 

 of the processes employed. 



Antimony may be deposited by simple immersion, and by 

 means of an electric current ; in the latter case the metal may 

 not only be obtained in a state of loose black powder, but also 

 in two distinctly different coherent reguline conditions, viz. as 

 a very brittle metal of a grey slate-colour and hard crystalline 

 structure ; and also in a highly lustrous steel-black deposit, of 

 amorphous structure. 



The solution used for obtaining the pure grey metal is 

 composed of : 



Distilled water 350 grammes. 



Tartar-emetic 30 



Tartaric acid 30 



Pure hydrochloric acid 45 



It is not a good conductor, and should be used with a current 

 of about 1 volt, so as to deposit about 1 millimetre per week. 



Mr. Gore describes a curious phenomenon which came 

 under his observation when depositing antimony. " If," he says, 

 "at any moment during the formation of the deposit the 

 piece is taken out of the bath and gently tapped or rubbed 

 with a hard substance, an explosion is produced accompanied 

 by a slight cloud of white vapours and sometimes with light, 

 and almost always evolving an intense heat. If the deposited 

 antimony is not homogeneous, the explosion attacks the subjacent 

 metal to a depth of 3 millimetres. Similar phenomena some- 

 times occur in the course of the electrolytic operation, when the 

 deposit rubs against the walls of the glass cell which contains 

 the solution." 



For obtaining a bright shining deposit, the following 

 solution can be used : 



Sulphate of antimony 500 grammes. 



Potassic carbonate .. 1 kilogramme. 



Water 8 litres. 



