E. W. Morley — Volumetric Composition of Water. 223 



But a difficulty which I have not yet surmounted proceeds 

 from impurities found in every sample of zinc which I have 

 heretofore obtained. The metal contains gases which were 

 absorbed by it during metallurgic processes ; of such gases, 

 carbon dioxide is but one ; this could be easily removed, but 

 there are present other gases which contain carbon ; until they 

 shall have been sufficiently investigated it is not certain 

 whether they can be removed by absorption. 



It is to be noted that this last difficulty is by no means re- 

 moved by amalgamating the zinc, and using it as one pole of 

 a voltaic element or of a decomposing cell. The best zinc I 

 have found gave when so used hydrogen which after combus- 

 tion in no very long time caused a precipitate in lime water. 

 The gas also contained nitrogen which came from the zinc 

 employed ;* I therefore abandoned for the present the use of 

 zinc. Dr. W. H. Burton kindly distilled in a vacuum for me 

 some kilograms of so-called perfectly pure zinc ; with which 

 product I shall some time resume the preparation of pure 

 hydrogen. 



Having abandoned, perhaps too hastily, the attempt to get 

 pure hydrogen from zinc, I resorted to electrolysis. The de- 

 composition of an alkaline hydroxide seemed promising ; by it 

 one would expect to get nothing but hydrogen, oxygen, hydro- 

 gen dioxide and ozone. From the decomposition of absolutely 

 pure potassium or sodium hydroxides, no doubt this pleasing 

 ideal might be realized. But two decomposing cells which I 

 constructed for the purpose and filled with so-called pure 

 potassium hydroxide yielded hydrogen containing carbon. 

 This might possibly come from organic matter adhering to the 

 interior of the cells, although I was at that time especially on 

 my guard against carbon ; but it was more probable that it 

 came from the simultaneous electrolysis of an alkaline carbon- 

 ate. I therefore made a new decomposing cell most carefully 

 of clean glass and platinum, cleaned it from organic matters 

 derived from glass blowing manipulations by long immersion 

 in chromic acid, but filled it with potassium hydroxide to 

 which I purposely added potassium carbonate. The electroly- 

 sis of this solution yielded hydrogen which instantly clouded 

 lime water on combustion. It was therefore plain that the 

 alkaline solution submitted to electrolysis must not contain any 

 carbonate. This might no doubt be attained by using barium 

 hydroxide, either alone, or added to potassium hydroxide to 

 remove carbon dioxide. But since the so-called pure potassium 

 hydroxide is purified by solution in alcohol, it is by no means 

 certain that it may not contain carbon other than that existing 

 in an alkaline carbonate. The matter, therefore, began to 



* Amer. Chem. Journal, vol. xii, p. 461, 1890. 



