Change of Oxygen into Ozone. 21o 



conclusions about air are those of Amagat {Ann. de Cliim. et 

 de Phys. [5] xxviii.) who between 12 millim. and 1 millim. 

 of mercury finds departures from Boyle's law in the same 

 direction as those indicated, but not of the amount that our 

 theory requires, Amagat not considering the departures to be 

 outside of the limits of experimental error, but it is hardly 

 worth while occupying space with reproducing these data, 

 since the Russian investigators Mendeleeff, KirpitschefF, and 

 Hemilian have found the departure for air to be always in 

 the direction just indicated but of variable amount. One 

 reason for this variability is shown in a pronounced form in 

 the remarkable experience which Baly and Ramsay had with 

 air in the capillary tube of one of their M'Leod gauges, in 

 which, while the pressure varied from 4*1 millim. to 8*0 

 the product pB fell from 100 to 9'4, a result to be explained, 

 like the corresponding one for oxygen, by the supposition 

 that in the unstable transition of part of the 2 into 3 some 

 ions of got liberated whose electrical repulsion produced 

 about 91 per cent, of the initial pressure of 4*1 millim., the 

 loss of the charge during the subsequent compression causing 

 the part of the pressure due to the electricity to diminish, 

 and pB, therefore, to diminish likewise. In view of the 

 possibility of a perturbing cause of this magnitude it is 

 obvious that special precautions will have to be taken in 

 studying the compressibility of rarefied air to get rid of all 

 electrical charge in the gas or the apparatus, and we can 

 understand the baffling nature of the variations encountered 

 by the Russian experimenters in their devoted work at this 

 difficult experimental research. 



According to our reasoning the amount of ozone in the 

 air at the surface of the earth ought to be a/760 or '11/760 

 per unit volume of air, or about one volume in 7000 if the 

 air were protected from all chemical actions. The estimates 

 of the actual amount of ozone in the air near the earth's 

 surface are very uncertain, but seem to indicate about one 

 volume in a million ; thus we are led to believe that oxi- 

 dation must be responsible for the destruction of the greater 

 part of the ozone that might theoretically be expected in the 

 air near the earth. But as we rise in the atmosphere to 

 a place where the pressure is p, the amount of ozone per 

 unit volume ought to be a/p till a region of discontinuity is 

 reached, after which the amount is u'/p till a point is reached 

 where the pressure is about *715 millim. of mercury, at 

 which and above which the whole of the oxygen exists as 

 ozone, forming about one-seventh of the volume of the air 

 there. These deductions have some hygienic importance 



