CHEMICAL SCIENCE. 



247 



ozone is invariably formed in the air by the action of artificial electrical 

 discharges, it should also be produced throughout the atmosphere, in 

 which natural electrical discharges occur. Nothing is easier than to 

 demonstrate the presence of ozone in the atmosphere, and the varia- 

 tions of the quantities produced, by means of the test-papers described. 

 In general, the reaction is greater in winter than in summer. Schon- 

 bein has always remarked that, during a fall of snow, it is much 

 greater than at any other time. An exposure of iodized and starch 

 paper for two hours is sufficient to render it of a deep blue color, 

 whereas the same air inclosed in a receiver produces no effect. It 

 may be inquired whether the nitric acid which is formed by passing 

 electric sparks through air, as first observed by Cavendish, and also 

 that produced by storms, are due to the direct action of electricity on 

 oxygen and nitrogen, or to that of ozone on nitrogen. (It has been 

 suggested, that the well-known fact of the souring of milk during 

 thunder-storms may be attributed to the action of ozone formed by 

 electrical action. Editors.) Such are the general properties of 

 a substance, the composition of which has hitherto escaped all meth- 

 ods of analysis, and which M. Marignac considers as a peculiar modi- 

 fication of oxygen, which increases its chemical affinities. Schonbeiri 

 regards it as a compound containing more oxygen than oxygenated 

 water. But all these are merely hypotheses which require the sanc- 

 tion of fresh experiments. Opinion as to the nature of the substance 

 should not yet be pronounced. Comptes Rendus, Jan. 14. 



Atomic Weight of Ozone. In Poggcndorff's Annalen, Osann pub- 

 lishes some additional researches on the atomic weight of ozone. 

 When ozonized air is passed through a solution of nitrate of silver in 

 ammonia, a black precipitate forms. This precipitate, after being 

 well washed and dried, yields on j-eduction by hydrogen 97.56 of sil- 

 ver to 2.44 of oxygen ; so that an o"xide of silver appears to exist having 

 the composition of Ag 3 O (which differs from the oxide discovered by 

 Wohler, Ag 2 0). If the ammoniacal nitrate of silver solution is ex- 

 posed to the air, there is formed in the course of a few weeks a thin 

 saline crust at the margin of the liquid, which is blackened, and ap- 

 parently contains the same oxide. This phenomenon exactly corre- 

 sponds with the behaviour of starch moistened with a solution of iodide 

 of potassium, which likewise turns blue in time by exposure. As no 

 analogous compound of silver and oxygen has been before obtained, 

 the inquiry is reasonably made, Is the black precipitate experimented 

 on in reality an oxide of silver, or a compound of silver with a pecu- 

 liar and new substance, ozone? This latter conjecture Osann is in- 

 clined to adopt, and calls the body for the present ozone-oxygen. 

 Supposing it to be a distinct body, it must have a separate atomic 

 weight, and this is found from its compounds with silver and lead to 

 be between 5.63 and 6.10. Various experiments seem to show that 

 ozone-oxygen has a definite atomic weight ; that it is by no means a 

 modification of oxygen, but a peculiar substance like chlorine, bromine, 

 &c., but whether of a simple or compound nature cannot be stated. 

 If it be admitted that ozone-oxygen is a distinct body, this will explain 

 in a most simple manner how oxide of lead is precipitated by ozone 



