





Chemistry and Physics. 317 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Properties of Highly Purified Substances. — In con- 

 sequence of recent experiments showing that many chemical 

 changes take place only in the presence of some substance, pre- 

 sumably water vapor, going to establish the general rule that all 

 chemical changes depend on the presence of this vapor, Shen- 

 stone has been led to study the apparent exceptions to this rule 

 more carefully. His first experiments were directed to determine 

 the influence of moisture (1) upon the production of ozone from 

 oxygen by means of the electric discharge, and (2) upon the sta- 

 bility of ozone. The apparatus used was quite elaborate, built 

 up entirely of glass and sealed before the blowpipe. It was 

 filled with oxygen, generated within the apparatus from a mixture 

 of potassium and sodium chlorates mixed with a little solid 

 potash, the ozonizer was set in operation and the resulting ozone 

 carefully dried with phosphoric oxide ; this operation being 

 repeated several times. Finally water vapor free from air was 

 admitted to the exhausted tube, and then oxygen, the apparatus 

 being cooled to 0°. The ozonizer was then put into operation 

 and the amount of ozone generated deduced from the resulting 

 contraction. The maximum yield of ozone was 13*6 per cent and 

 the minimum 13 # 3. Repeating the experiment with the oxygen 

 dried so that the pressure of the aqueous vapor present was 

 assumed to be not over # 0001 mm , the yield never exceeded 11*1 

 per cent. Moreover, the ozone obtained appeared to be singu- 

 larly instable. Direct experiment showed that moist oxygen well 

 ozonized, could be maintained at 26*4° for 9 hours with a loss of 

 only 2 per cent, the loss during the last 4 hours being only 0*4 

 per cent. Dry oxygen, on the other hand, when strongly ozonized 

 and kept at 0° for 33 minutes, lost 1*6 per cent of its ozone. 

 Hence it appears that moderately dry ozone at 0° undergoes 

 decomposition about 30 times as rapidly as the damp gas at 26'4°. 

 On drying the oxygen still more completely (so that the water- 

 vapor pressure had been reduced to -000,000,00 l mm ) only 0*2 per 

 cent of ozone was formed ; showing that well-dried oxygen 

 scarcely ozonizes at all. In a second series of experiments, the 

 behavior of carefully dried chlorine, bromine and iodine with 

 well-dried mercury was studied. The chlorine was generated by 

 the electrolysis of fused silver chloride within the apparatus, a 

 large Fleuss pump and two five-fall Sprengels being used to pro- 

 duce the exhaustion. The bromine and iodine used were also 

 purified with great care. The mercury was prepared from mer- 

 curous nitrate or mercuric oxide, and repeatedly distilled. All 

 the materials were dried with the greatest care. On introducing 

 the mercury in a glass bulb into a tube and then filling this with 

 the chlorine, bromine or iodine, it was observed that on breaking 



