DYNAMO-ELECTRIC MACHINES. 87 



resistance indicated by us, and at the very first trial we could 

 deposit 600 grammes of silver per hour in the four baths, with 

 a speed of 300 revolutions per minute. 



"The service rendered by his machine to the electro- 

 chemical industry has been so considerable, the economy in 

 the production of work has been so great, that it has allowed 

 of certain applications which the high price of the battery and 

 its costly maintenance had prohibited, or which could not be 

 thought of. 



" The electro-deposition of iron, tin, nickel, and electro- 

 metallurgic refining are proofs of it. 



"In order to illustrate the importance of the industrial 

 revolution accomplished by the Gramme machine, we will 

 give you some interesting figures of absolutely correct cost 

 prices, for they are established on a considerable production 

 and on averages of five years' manufacturing work. 



" \Yith the battery, the kilogramme of silver entailed an 

 expenditure of 3 87 francs for the galvanic current. 



" With the Gramme machine, taking into account the value 

 of the motive power, the interest of the capital, and the wear 

 and tear of the material, the cost of depositing silver is reduced 

 to 94 centimes per kilogramme (0*94 franc). 



"This economy seems insignificant when it applies to 

 precious metal, like gold and silver, the intrinsic value of which 

 is considerable, but it is important when a common low price 

 metal, like copper, tin, iron and nickel, has to be deposited. 



"The success of the Gramme machine has been so consider- 

 able that the company which works it has sold not less than 

 500 machines to electro-metal lurgic factories alone. 



" We have taken the opportunity which presented itself of 

 speaking here of the Gramme machine, because at the very 

 moment when the electrical exhibition displays the marvels 

 which it has created, the progress of which it has been the 

 starting point, and the great future which there is in store 

 for the electrical industries using it, it has seemed to us a fit 

 occasion for calling to mind the part, however modest, which 

 Messrs. Christofle have taken in the industrial realisation of 

 M. Gramme's invention." 



