MAGNETO-ELECTRIC MACHINES. 43 



been introduced to any extent in the factory. When used in 

 series, the advantages it possesses over Wollas ton's do not counter- 

 balance the extra labour and expense attending its use, and many 

 who have tried it in the operations of the factory have for these 

 reasons given it up. 



Earth Battery- The fact that when a piece of copper and a piece 

 of zinc are imbedded in the earth there is a current of electricity 

 obtained from them in the same way as if they were placed in any 

 battery trough, instantly suggested the application of the earth, or 

 what is termed an earth battery, to the purposes of depositing. We 

 need hardly say these trials were without success. The electricity 

 obtained in this way is very weak, depending wholly upon the mois- 

 ture of the earth, and the arrangement forming therefore simply a 

 water battery. We have made electrotypes by this means, and also 

 plated small articles, but the action or deposition is very slow. We 

 have obtained a greater amount of deposition in five minutes from one 

 square inch of zinc and copper placed in dilute sulphuric acid, than 

 from four square feet of zinc and copper placed in the earth in the 

 space of an hour. An earth battery adapted to deposit from 150 to 

 200 ounces of silver per day would require acres of land. 



In this, as in all other forms of battery, the deposit is in relation 

 to the zinc oxidated in battery; there would, therefore, be no eco- 

 nomy in using the earth battery, and to lessen the amount of surface 

 required by an intensity arrangement would not alter the law, but 

 rather add to the expense, as it would require upwards of 100 pairs 

 in the earth to be equal to 3 or 4 pairs of Wollaston's for the object 

 of depositing; and would thus be adding to the cost of depositing 

 one hundred times the equivalent of zinc instead of four times its 

 equivalent. 



Magneto-Electric Machine. Several years ago, Mr. Woolrich, of 

 Birmingham, patented a discovery for applying to the deposition of 

 metals the electricity obtained from magnetism or the magneto-electric 

 current, instead of voltaic electricity. We have never had an oppor- 

 tunity of operating with Mr. Woolrich's machine, nor of seeing it 

 in operation for the purpose of deposition. We cannot speak of it 

 from experience ; but, from a statement made at the meeting of the 

 British Association in 1850, by Mr. Elkington, of Birmingham, who 

 is .the proprietor of the patent, and a gentleman of most extensive 

 experience, it would seem that he had up to that time never been 

 induced to give up the ordinary battery in favour of magnetism, or any 

 other suggested improvement. We understand, however, fchat this 

 means of obtaining the electricity for the purposes of electro-metal- 

 lurgy has recently been much improved by forms of magnets, &c., 

 patented by Mr. Millward, and described by him as follows: "The 

 first branch of the improvements is carried into effect by the em- 



