266 ANNUAL OF SCIENTIFIC DISCOVERY. 



as the atoms of two heterogeneous substances combined together? Various 

 secondary reasons, however, may be of influence. In the first place, the 

 state of aggregation must be considered. In a solid metallic oxide or perox- 

 ide, the several parts are fixed in position with respect to one another; and 

 we may therefore presume that the oxygen atoms do not come into that 

 contact with one another which is necessary for combination. A fluid body, 

 on the contrary, adapts itself better upon a solid one, and its particles pos- 

 sess, at the same time, the necessary mobility. The same is the case with a 

 gaseous body; and such a one, in addition, undergoes a condensation on the 

 surface of the solid body. It may, moreover, be the case, that the equally 

 electrified condition of the oxygen atoms of a definite compound renders 

 them less disposed to combine with one another than with the non-electric 

 ozone, or with the oxygen atoms of another compound, whose electrical 

 state may possibly be a different one. Moreover, the electrical conducti- 

 bility of the substance may be of influence, inasmuch as those alterations of 

 the electrical condition which are necessary for combination, may take place 

 more easily in contact with metallic bodies than in the interior of badly-con- 

 ducting bodies. Probably still further reasons might be given in answer to 

 the question proposed; but those already advanced may suffice, at all 

 events, to show how numerous the influencing circumstances may be, and 

 how vain it must be to expect to find the phenomena following some simple 

 law which holds good in all cases. 



Finally, I must remark, that the density of ozone, as given by Andrews 

 and Tait,* according to whom it would appear to be nearly four times as 

 great as that of ordinary oxygen, is contradictory of my hypothesis concern- 

 ing the nature of ozone. If, however, we reflect, that the experiments could 

 only be tried with oxygen containing comparatively little ozone, and that, 

 in order to convert the ozone into ordinary oxygen, the whole was heated to 

 230 C., or more, it is easy to perceive how extremely difficult it must have 

 been to remove the disturbing influences so far as to attain the requisite 

 . degree of accuracy. For this reason, then, without in the least calling in 

 question the skill and care of the experimenters, I have, nevertheless, hesi- 

 tated to attach sufficient weight to the results they have found, to induce me 

 to suppress my hypothesis. Philosophical Magazine. 



At the Bseds meeting of the British Association, 1858, Dr. Lankester 

 exhibited an instrument for measuring the intensity of ozone, which con- 

 sisted of two small rollers included in a box, which were moved by means 

 of ordinary clockwork. Over the roller a strip of paper, prepared with iodide 

 of potassium and starch, is allowed to revolve, the paper being exposed to 

 the air from an inch of open surface in the lid of the box. Twenty-four inches 

 of paper pass over the rollers in the course of the twenty -four hours, and thus 

 registers, by its color, the intensity of the action of ozone in the atmosphere. 

 By this instrument the intensity of the ozone for every hour in the twenty- 

 four could be registered, and minima and maxima, with an average, be ascer- 

 tained. The register of ozone could also be compared with those of the 

 anemometer, and the relation of ozone to the direction and force of the wind 

 ascertained. Dr. Lankester pointed out the importance of ascertaining the 

 presence of ozone, on account of its undoubted relatidh to health. He drew 

 attention to a series of tables which had been drawn up from the registra- 



* Proceedings of the Foyal Society, vol. viii., p. 498, and Phil. Mag. for February, 

 1858, p. 146. 



