No. Vm.] APPENDIX. 185 



" The hundreds of experiments, I may even say the thousands, that 

 have been tried to elncidate these laws (for this book is not a detail of 

 experiments, but rather a digest of them), could never have been executed 

 had I not first discovered my galvanic battery ; for its simplicity alone 

 enabled me, without any assistance, to undergo the laborious undertaking. 

 I am fully awaxe that some may disagree with me as to the superiority of 

 my battery over aU others for experimental and manufacturing purposes. 

 I shall not flinch on this account from stating its advantages, especially as 

 they appear to me likely to contribute to general benefit. 



" The value of the battery process over ail others is its applicability 

 to all cases; moreover, when we use a single cell of the battery, the 

 quantity of the zinc dissolved to do any amount of work is the same, or 

 even less, than attends the use of the other apparatus, because the local 

 action in a battery of this construction is less than in the single-cell 

 apparatus ; and, lastly, the quality of the precipitated metal can be 

 regulated with the utmost nicety ; and I have no hesitation in stating that 

 the battery process is the only one that ever can be employed by the manu- 

 facturer with advantage 



" The departments of electro-metaUuxgy comprising electro-gilding 

 and plating, received great impulses from Elkington ; some of his processes 

 being most admirable. As far as gilding is concerned, he was anticipated 

 by Brugnatelli nearly forty years ago, for which see letter of BrugnateUi 

 to Van Mons, in the 'Phil. Mag.' for 1805, also 'Archives of Philoso- 

 phical Kjiowledge.' The process by Brugnatelli differs in nothing from 

 the one now employed, and doubtless ought to be considered as the 

 introduction of electro-metallurgy, being the first instance in which any 

 metal was ever reduced by galvanism for the purposes of the arts. 



" The processes for platinating, palladiating, &c., rest upon the 

 authority of this work ; for hitherto the reduction of these metals, in 

 any other state than that of the black powder, has been always considered 

 impossible. The electro-metaUurgist will be enabled, by the processes which 

 he will find here fully described, to execute reliefs and intaglios in gold, 

 and, in fact, in nearly every other metal; facts altogether new in science. 

 The working of all other metals, as zinc, silver, &c. &c., except copper, 

 is also due to the discovery of the laws regulating the precipitation of 

 the metals. 



" Every author has given directions for making moulds on plaster 

 casts in metal ; but it is singular that by no process hitherto known can a 

 perfect reverse plaster be obtained. In investigating the cause of this, 

 I soon discovered that the extreme porosity of the plaster was the block 

 over which they had all stumbled, and the difficulty was overcome by 

 rendering the plaster non-absorbent. In this work the reader will find 

 that the copying of reliefs in plaster is brought to the utmost possible 

 perfection, and by very simple means. 



" The success of this department of my experiments has amply repaid 

 me for my labours and expense ; for there is not a town in England that 

 I have happened to visit, and scarcely a street of this metropolis, where 

 prepared plasters are not exposed to view for the purpose of alluring 

 persons to follow the delightful recreation afforded by the practice of 

 electro-metallurgy. 



" The extended use of white-wax, bees'-wax, rosin, &c., for the electro- 



