﻿80 Intelligence and Miscellaneous Articles. 



For 10 litres of odorant gas the proportions of ozone found were — ■ 



milligrammes. 

 36-00 

 3'90 

 9-00 

 (2) The same experiments made in air prove that no nitrous com- 

 pounds are formed in the atmosphere which emerges from Ladd's 

 condenser. 



The proportion of ozone formed is less than with pure oxygen. 

 For 10 litres the numbers found are — 

 milligrammes. 

 3'8 

 3-7 

 27 

 The successive diminution in the numbers quoted is due to the 

 decrease in the intensity of the electrical source, since the results of 

 experiments made near each other are almost identical. In a subse- 

 quent research we shall give the relation which may exist between 

 the degree of ozonization of the atmosphere and the length of the 

 spark. We can even now say that the discharge of a coil far smaller 

 than that used for the above experiments (producing a spark of 3 cen- 

 tims. instead of'20) communicatesalmost as strong an odour to the gas. 

 This point is the more interesting to clear up, since experiments 

 prove that this condenser is a continuous source of ozone for air tra- 

 versing it; and since this air does not become charged with any trace of 

 nitrous compounds, the detrimental influence of which on the organs 

 of respiration is well known, this ozonized atmosphere, therefore, 

 would not be at all injurious if it were introduced by ventilation. 



We propose to decide by other experiments how far the difference 

 of chemical activity may extend which at present seems to exist be- 

 tween the direct spark and that of condensation. — Comptes Rendus, 

 September 21, 1868. 



NEW METHOD OF ESTIMATING MINUTE TRACES OF METALS, SPE- 

 CIALLY DESIGNED FOR WATER-ANALYSIS. BY J. ALFRED 

 WANKLYN, PROFESSOR OF CHEMISTRY IN THE LONDON INSTI- 

 TUTION, AND ERNEST THEOPRON CHAPMAN. 



In the concluding chapter of our short treatise on water-analysis, 

 we made mention of the possibility of the presence of very minute 

 quantities of metals in drinking-water exercising a considerable in- 

 fluence on the health of the community. A method of detecting 

 and measuring these minute traces of metals was wanted. We are 

 now able to supply the want. 



Availing ourselves of the circumstance that sulphuretted hydrogen 

 does not precipitate, but simply colours a very dilute solution of cer- 

 tain metals (the depth of coloration following the quantity of metal 

 present in the solution), we have devised and practised a method of 

 titration which is for certain metals much what the Nessler-titration 

 is for ammonia. In this way we have measured the amount of lead 

 in a specimen of Manchester water. 



The practical details of the process, together with examples, will 

 be published on a future occasion. 



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