Mr. Williamson on Ozone. 373 



.iuv:.' ■ ■ ■ . •■ . i/ 



lected in a small tubulated glass bell placed over it, and two- 

 thirds sunk in the liquid. Hence it was conveyed into a tube 

 filled with chloride of calcium, through which it passed with- 

 out any diminution of its peculiar smell. The oxygen thus 

 (hied was conducted into a glass tube filled with copper turn- 

 ings and heated to redness. At the further end of this tube, 

 which was kept cool, globules of water soon made their ap- 

 pearance, which on being removed were speedily reproduced, 

 and continued increasing so long as the process lasted. The 

 -oxygen, on entering the tube full of copper, being quite dry, 

 it thus appears that water is formed by the reducing action of 

 the heated metals ".' i^-»^'" alOicjjt vUhi j/fub i. 



In the manner "of peifotmin^ this e^peHmfent, there are two 

 circumstances which take from the result the certainty of cor- 

 rectness necessary for drawing conclusions. These circum- 

 stances are the following: — 



1st. The copper turnings having, by heating to redness in 

 the air, been covered with a coating of oxide, were reduced 

 by means of a current of hydrogen gas, and although the ex- 

 cess of that gas had been removed as far as possible by a cur- 

 rent of dry atmospheric air, yet it was possible that some 

 hydrogen might adhere to the porous copper, which would 

 account for the formation of water on oxygen being brought 

 to the hydrogen at a red heat. , *, , ' 



2nd. Hydrogen being somewhat soluble in water, the oxy- 

 gen may in passing through the liquid have taken up some 

 traces of that element, and on coming in contact with the 

 heated metal the two gases would combine. 



To obviate the first of these objections, the oxidated copper 

 was reduced by a current of dry carbonic oxide gas, and to re- 

 move the possibility of free hydrogen being carried over with 

 the oxygen, the latter was passed through a tube filled with 

 spongy platinum, and then again over chloride of calcium. It 

 was, however, found that the substance producing the peculiar 

 odour was either decomposed or absorbed by the platinum, 

 none of it passing over. 



The difficulty was at length avoided by evolving the oxygen 

 from a liquid in the decomposition of which no hydrogen is 

 set free. Oxide of copper dissolved in sulphuric acid was 

 decomposed instead of water. The oxygen then evolved pos- 

 sessed precisely the same odour as that from acidulated water, 

 and after careful drying was conducted into the heated tube 

 containing copper turnings reduced by carbonic oxide. 



Water speedily appeared at the cool end of the tube, and 

 the quantity continued increasing as long as the process lasted. 



In subsequent experiments, oxygen prepared in the manner 



