VOLUIMETEIC EELATIONS OF OZONE. 
125 
three vessels in line and passing the same stream of electrolytic oxygen through them 
all. By heating the first and last vessels to 300° C., and observing the expansion pro- 
duced in each, it* was easy to calculate the expansion which would have occurred in the 
middle vessel, if it had been exposed to similar treatment. This expansion was assumed 
to be equal to the contraction which occurs when ozone is produced from oxygen by 
means of the electrical discharge. Finally, the actual amount of ozone in the middle 
vessel was determined by introducing a solution of iodide of potassium, and ascertaining 
by analysis the amoimt of iodine set free. The mdmdual experiments with electrolytic 
ozone did not agree so well mth one another as those performed with ozone prepared 
by the discharge. This arose partly from the very small quantity of ozone in electro- 
lytic oxygen, but chiefly from the irregularity in that quantity at different times, even 
when the current was passing very steadily, which made it difficult to ascertain with 
certainty the expansion due to the ozone in the middle vessel. Our earlier results, 
indeed, gave a measurable volume for ozone, and as a first approximation we obtained the 
number 4 as expressing its density *. But, by multiplying our experiments, and taking 
all possible precautions to ensure accuracy, we found that electrolytic ozone, like that 
produced by the discharge, has no appreciable volume. 
Ozone is not condensed at common pressures by the cold produced by a mixture of 
solid carbonic acid and ether. A stream of electrolytic oxygen, passed very slowly, first 
through a U-tnbe surrounded by snow and salt, and next through a spiral tube immersed 
in the carbonic acid and ether bath ( — 76° C.), underwent no change. The ozone 
reactions, as the gas issued from the tube, after exposure to this low temperature, were 
as strong as before it entered the bath. 
§G. 
llijflrogen, prepared with care by the action of dilute sulphuric acid recently boiled 
on zinc, and purified by passing through three U-tubes containing corrosive sublimate 
in solution, hydrate of potash, and sulphuric acid, respectively, and finally, in order to 
remove the last trace of oxygen, through a tube filled with metallic copper heated to 
redness, was found not to be altered in volume, either by the sparks or by the silent 
discharge. It appears to be a much better conductor of electricity than oxygen. 
\\ ith Isitrorjen^ prepared in the usual way by depriving atmospheric air of its oxygen 
by means of heated copper, the results were also negative. 
Among the compound gases. Carbonic Acid is rapidly decomposed by the spark, slowly 
by the silent discharge ; in botli cases expansion takes place. 
Cyanogen is at once decomposed by the spark with deposition of carbon (I) ; bnt pre- 
sents so great a resistance to the passage of electricity, that the action of the silent dis- 
charge could not be ascertained with certainty. 
Protoxide of Kitrogen is readily attacked by the spark, Avith the formation of hypo- 
nitric acid, whose characteristic red colour is distinctly seen. The primary result of the 
* Proceedings of the Eoyal Society, vol. viii. p. 498, and vol. ix. p. 606. 
S 
MDCCCLX. 
