xxvi GENERAL SUMMARY OF SCIENTIFIC AND 



Much light, it is to be expected, will be thrown upon chem- 

 ical constitution and chemical changes by accurate determi- 

 nations of the heat produced or absorbed in these changes. 



In General Chemistry the ozone question has received much 

 attention. A. W. Wright has devised a most efficient form 

 of ozonizing tube for use with the Holtz machine, and M. 

 Houzeau, also, an excellent ozonizing tube for use with the 

 induction coil. By means of this apparatus of Houzeau's, it 

 is possible to obtain from 60 to 120 and once even 188 

 milligrams of ozone in a litre of oxygen ; more than quadru- 

 ple the amount given by previous methods. This ozonized 

 oxygen is exceedingly active, oxidizing alcohol to aldehyde 

 and acetic acid almost instantly, forming, at the same time, 

 hydrogen peroxide. Great care is needed in experimenting 

 with it, since, when breathed, it causes serious irritation of 

 the lungs, often with bloody expectoration. The deodorizing 

 power of pure ozone is estimated to be forty times that of 

 chlorine. Houzeau estimates that the air of the country, 

 two metres from the ground, contains 45U 1 (M)U of its weight 

 of ozone. Carius has observed that a litre of water dissolves 

 four or five cubic centimetres of ozone. He states that the 

 ozonized water sold in Berlin contains about four centime- 

 tres of ozone in a litre. The oxidizing power of ozonized 

 air is well illustrated by an observation of Professor Wright. 

 He noticed that the sulphur of the vulcanite casing of his in- 

 duction coil became converted, when the coil was in action, 

 into sulphuric acid, which even accumulated in drops upon 

 this casing. The commercial preparation of chlorine by Dea- 

 con's process having been proved a success, the inventor has 

 made a most elaborate scientific investigation of it, the ex- 

 periments extending over four years, and being made witli 

 the greatest care. This process, as is well known, consists in 

 passing a mixture of hydrochloric acid gas and oxygen over 

 copper sulphate, or other copper salt, heated to 700 or 750 

 Fahr. The copper salt is obtained in the best condition by 

 soaking pieces of brick in it and then drying them. The ac- 

 tion of the copper salt being of the kind called catalytic, an 

 action of presence simply, the precise character of that ac- 

 tion it became of importance to ascertain. Deacon finds that 

 the amount of hydrogen chloride decomposed, other things 

 being equal, depends upon the number of times the mole- 



