84 Transactions of the 



of a photographic image is the result of a chemical change, 

 and not founded on any mechanical theory. 



The diffusive power of ozone is about that of carbonic 

 acid. Its computed density is 1*658. 



Ozone, even when extremely diluted, has the power of 

 liberating iodine from iodide of potassium (KI), and on this 

 property, in conjunction with that of free iodine, to form 

 with starch (CgHigOj), a blue compound is founded, one of 

 the most delicate, although not characteristic, tests for its 

 presence. 



In March last year, M. Fontaine was makmg some expe- 

 riments in his laboratory, near Paris, with potassic picrate 

 (KCgHglSTjOy), when it exploded with frightful violence with- 

 out any apparent cause, blowing several persons to atoms, 

 and among them M. Fontaine's eldest son. The state of 

 the atmosphere was the onlj^ cause that could be assigned 

 for the accident, and M. Houzeau, having observed that the 

 quantity of ozone in the air at Paris on that particular day 

 was higher than it had ever been recorded before, tried the 

 experiment of introducing a small piece of picrate of potas- 

 sium into a phial of ozone, when a frightful detonation took 

 place and the phial was smashed to atoms. Nitro- glycerine 

 (CijHg^lSrigOjg), dynamite, chloride and iodide of nitrogen 

 (11012^.013^ and HMgNIj), and several other substances, 

 whose constituent atoms are loosely held together, instantly 

 explode on being introduced into an atmosphere of ozone. 

 Ozone, when heated to 550° F (288° 0) is reconverted into 

 ordinary oxygen. Ozone is destroyed by contact with india- 

 rubber, cork, and nearly all vegetable or animal substances ; 

 the hydrogen and carbon contained in the organic matter 

 being oxidized to water (H2O) and carbonic acid (COj). Ozone 

 has no action upon the following substances : — 

 Urea (CH^N.O), Hippuric acid (C9H9NO3), 



Allantoin (C,HgN403), Alloxan (C^H^N^OJ, 

 Creatine (C4II9N3O2.H2O), Cencine. 

 Fibrine (C2oH3,N50g) Gelatine (04iHg7E'i30,6) 



Starch (CgH,gO,), Sugar (C,2H220„), 



Inosite (CgH,2062H20) Amygdaline {C,^B.„'NO^^S'R^O), 

 Salicine (C,3Hi807), Albumen (fresh) (CyjHjjjNigSOjj), 



and some others. 



In contact with ozone, albumen (C72lI,,2!N",8S022) becomes 

 slightly coloured, and then forms a coagulum analogous to 

 fibrine (C2oTl3,]S]"50e), but insoluble in nitric acid (HNO3) ; when 

 it has absorbed the maximum possible it cannot be coagu- 

 lated by heat, nor is it precipitated by mineral salts with the 



