54 Dr. M. Baumert on a new Oxide of Hydrogen 



The greatest divergence from the mean of these experiments 

 therefore amounts only to 0*00001 of iodine, and represents an 

 error of only 10 * 000 of oxygen. The chances of error in the 

 determination of the oxygen is thus, according to these experi- 

 ments, so far reduced, that the quantity of this element may be 

 determined even in less than the tenth of a milligramme of ozone. 



The errors most likely to creep into this method must conse- 

 quently be in the weighing ; for this reason the operation was 

 performed with particular care. A new (Ertling's balance was 

 employed, which was never made use of for any other purpose 

 during the whole course of the experiments, by means of which 

 even the tenth of a milligramme might be determined with cer- 

 tainty. The balance was placed in an unheated place, the tem- 

 perature of which was pretty constant. The preliminary weigh- 

 ing before the experiment, as well as that after it, was two or 

 three times repeated, when the apparatus, protected from the 

 access of moisture, remained for a considerable time in the closed 

 balance exposed to a constant temperature. The difference of 

 temperature observed during the weighings did not exceed 5°*4F., 

 whilst the weight of the apparatus was 36 to 38 grms., so that 

 the influence of the temperature might be disregarded. On the 

 other hand, the greatest care was taken to displace the oxygen 

 remaining behind from the passage of the electrolytic gases by 

 a stream of dry air before the weighing. In this manner it was 

 possible to accomplish the weighings with accuracy to a few 

 tenths of a milligramme. This represents an immaterial error as 

 regards the composition to be ascertained. 



The preparation of ozone presents greater difficulties than its 

 analysis. Water acidulated with sulphuric acid, and decomposed 

 by the electric current, does not furnish sufficient ozone to be 

 weighed with precision. On the other hand, by the electrolysis 

 of chromic acid containing sulphuric acid, such quantities are 

 evolved, that vulcanized india-rubber tubes of a line in thick- 

 ness are destroyed by it in a few minutes ; and the stream of 

 oxygen bearing the ozone with it forms white clouds with am- 

 moniacal gas, which on closer examination are found to consist 

 of nitrate of ammonia. It would, however, be a great mistake 

 to suppose that ozone is to be obtained pure in this manner ; 

 its quantity, in spite of this powerful action, is so small, that in 

 the whole of the following experiments it was necessary to evolve 

 not less than from 700 to 800 litres of electrolytic gas. In one 

 experiment, in which 76 grms. of water acidulated with T \jth of 

 sulphuric acid were decomposed, 150 litres of explosive gas were 

 accompanied by 1 milligramme of ozone. Solutions of chromic 

 acid, which still contained some sulphuric acid from its prepara- 

 tion, furnished 1 milligramme of ozone to 10 litres of gas in two 



