10 DR. ANDREWS ON THE CONSTITUTION AND PROPERTIES OF OZONE. 
the mixed gases. The relative quantity of ozone to the amount of water decomposed 
is less than in the former experiments, arising perhaps partly from a single platina 
wire having been in this case employed as the positive pole. In this experiment, 
great care was taken to exclude both carbonic acid and nitrogen from the electrolyte. 
My next object was to determine, by careful quantitative experiments, whether 
water is really formed, as Williamson and Baumert have stated, when ozone is 
decomposed by heat. For this purpose, the same general arrangement was employed 
as in the first series of these experiments ; but the first Liebig’s apparatus D, instead 
of being filled with a solution of iodide of potassium, was now empty, and placed in 
the upper part of a metallic cylinder (fig. 4 HH), where it was raised to a tempe- 
rature of about 400° C., by a current of heated air from a Leslie’s burner. To the 
sulphuric acid apparatus E, was permanently attached and weighed along with it, a 
small U-tube G, containing anhydrous phosphoric acid, so as to secure the condensa- 
tion of the last trace of aqueous vapour, if any were present. The oxygen gas was 
collected and measured as in the former experiments. 
Two experiments were made. In the first, 6'8 litres of oxygen containing 0*027 grni. 
ozone were passed through the apparatus ; in the second, 9*6 litres containing 0*038 
grm. ozone, d’he compound sulphuric and phosphoric acid apparatus was found, all 
corrections having been made, to have increased, in the one case one-third, and in 
the other case one-half of a milligramme in weight. Such quantities can only be 
referred to the unavoidable errors of experiment. If ozone were a compound body 
having the constitution HO 3 , the apparatus would have gained in the first experi- 
ment 10, and in the second 14 milligrammes. 
That ozone cannot contain nitrogen will appear from the following experiment. 
Two platina wires were hermetically sealed into the bottom of a small flask, into 
which water, containing a little sulphuric acid, was introduced and made to boil 
rapidly for some time. While the water was in a state of ebullition, the wires were 
connected with the poles of a voltaic arrangement, so as to disengage the mixed gases 
along with the vapour of water. So long as the ebullition continued, no ozone made 
its appearance ; but on allowing the liquid gradually to cool, without arresting the 
current, its presence soon became manifest from its odour and action on iodide of 
potassium paper. The ebullition and the current of the mixed gases must have 
rendered the presence of nitrogen here impossible. 
One question still remains to be answered. Does ozone, besides oxygen, contain 
any other constituent which is not absorbable by any of the reagents employed? 
Although the gas which escaped from the apparatus, after the separation of the ozone, 
appeared to be pure oxygen, yet it would be rash to assert that it might not have 
contained some unknown body amounting to of its weight, and having no 
very salient properties. This question appeared to me to admit of solution in another 
way. It will be seen, in a subsequent part of this paper, that there can be no doubt 
of the formation of ozone from pure and dry oxygen by the action of the electrical 
