CHEMISTRY. I33 



phorus has been kept, iodine is liberated. The reaction is 

 due to the phosphorous acid present. To detect an iodide, 

 this is first oxidized by boiling with a few drops of sodium 

 hypochlorite. The addition of the phosphorus water sets 

 free iodine at once, which is recognized by starch or carbon 

 disulphide. 



Berthelot has studied the thermic conditions attending the 

 formation of ozone. He finds that in the production of one 

 molecule of ozone from oxygen there is an absorption of 29.6 

 calories. Being therefore a body formed with the absorption 

 of heat, its activity chemically is accounted for : it is a maga- 

 zine of energy stored up under the influence of electricity. 



Cohne has observed that if a sprig of any fresh plant be 

 placed in a weak solution of hydrogen peroxide, oxygen is 

 disengaged which is strongly ozonized. If flowers are upon 

 the sprig, they also evolve oxygen, but less actively. A con- 

 venient method of setting free a little ozone in the air of an 

 apartment is to place a bouquet of flowers in weak hydrogen 

 peroxide in place of ordinary water. 



Kammerer has called attention to the occurrence of gelatin 

 in all forms of water coming from the soil, and has suggest- 

 ed that water intended for consumption should always be 

 tested by means of tannin for this substance. If no precipi- 

 tate or turbidity appears after standing twenty-four hours, 

 the absence of an appreciable quantity of gelatin is assured. 

 Any turbidity, however, proves the water impure. 



Frankland has published a paper on water- analysis, in 

 which he examines the value of the albuminoid -ammonia 

 process, and concludes that it is "entirely useless in the ex- 

 amination of waters for sanitary purposes." He claims, 

 however, for the combustion process, that it is the only one 

 which gives trustworthy information concerning the organic 

 matter present, the only one which can determine the car- 

 bon, and the only one which shows the ratio of nitrogen and 

 carbon. 



Fairley has studied the action of various bodies on hydro- 

 gen dioxide, with a view to determine the cause of the de- 

 composing action they exert. In the case of the metals 

 silver, for example he believes that there is first an oxida- 

 tion, and then a reduction again, due to the reaction of the 

 silver oxide upon the hydrogen dioxide. 



