very meager, the bibliography of the deposition of metals giving very little 

 light. 



Dr. AYilliam H. AVahl. of Philadelphia, has written a pamphlet which 

 deals with the subject qualitatively and in a rather indefinite manner. In 

 the investigation several problems presented themselves for solution, 

 among them being the following: 



I. The metal that shall be used for the cathode; 

 II. The solution of platintim to use for electrolyte; 

 III. The current density that gives the best character of deposit at the' 



most rapid rate: 

 lY. The concentration of solution tliat gives best results; 

 V. The temperature that gives highest efficiency and best character of 



deposit: 

 VI. If the foil is porous or granular, the way to treat it so as to remedy 



the defect and get a dense, tough deposit; 

 YII. The liquid that will dissolve the metal of the cathode and leave the 

 platinum foil intact. 

 Most of these problems are very closely related, so that results for 

 several were sometimes obtained from the same set of experiments. 



On accoimt of the smooth surface it will take, the ease with which it 

 may be dissolved, that it Avill take a deposit of another metal so readily, 

 and that it can be rolled into thin sheets, copper seems the best metal for 

 the cathode. The anode, of course, should be platinum, carbon or other 

 substance that will not be acted on by the nascent gas set free in the reac- 

 tion. 



II AND III. 



The salt of platinum used must be such that it is easily dissolved and 

 will start up no harmful secondary action during the passage of the cur- 

 rent. Platinic chloride will not serve on accoimt of this last restriction. 

 Platinic hydrate, hoAvever. is almost ideal and was used in all experi- 

 ments. 



At first an effort was made to use platinic hydrate dissolved in oxalic 

 acid, forming oxalate of platinum, the proportions used being— 



1 oz. platinic hydrate, 



4 oz. oxalic acid, 



4000 c.c. distilled water. 



