116 M. Thenard on Onjgenated Water. 



slightly agitated. When the solution is made, pure and concen- 

 trated sulphuric acid is added, drop by drop, the fluid being 

 stirred at the time with a glass rod, until there is a slight excess 

 of it, which is easily known by the property possessed by the 

 sulphate of barytes formed at the moment, of readily depositing 

 in flocculi ; then, as at first, a fresh quantity of deut-oxide is 

 dissolved in the fluid, which is again precipitated by sulphuric 

 acid. The deut-oxide is always easy to distinguish from the 

 sulphate. It is important to add enough sulphuric acid to pre- 

 cipitate all the barytes, but not too much. If enough is not 

 added, the fluid filters with difficulty, and slowly ; if too much 

 is added, the filtration also goes on badly. On arriving at the 

 exact point mentioned, the filtration takes place with the utmost 

 facility. When the filtration is completed, a small quantity of 

 common water is to be passed through the filter, and added to 

 the first fluid ; in this way the latter does not lose in volume : 

 then, that nothing may be lost, it is necessary to spread the filter 

 on a glass plate, to separate the substance from it, diff'use it 

 through a small quantity of fresh water, and filter it. The water, 

 thus obtained, is but slightly charged, but it is useful to wash the 

 future filters. 



This operation being finished, another is made exactly similar 

 to it, i. e., deut-oxide of barium is to be dissolved in the fluid-; the 

 barytes is to be precipitated by sulphuric acid, and so on ; and the 

 fluid is not to be filtered until after two solutions, and two pre- 

 cipitations. It is on this new filter that the water obtained by 

 washing the precipitate in the preceding operation is to be poured ; 

 after which fresh weak water is procured by washing the matter 

 on the last filter. 



The second operation is followed by a third, that by a fourth, 

 and thus, until the fluid is sufficiently charged with oxygen. By 

 using the quantity of hydro-chloric acid mentioned, from 90 to 

 100 grammes (29 to 32ozs.) of deut-oxide of barium may be 

 operated on, and a fluid will be obtained charged with 25 or 30 

 times its volume of oxygen. If it is required to be further oxyge- 

 nized, more hydro-chloric acid must be added. 



I have many times succeeded by this means in charging the 



