M, Thenaid on O.iygenafed Water. 115 



1. Nitrate of barytes should first be obtained perfectly pure, 

 and, above all, free from iron and manganese. The most certain 

 mean of procuring it is to dissolve the nitrate in water, to add 

 to the solution a small excess of barytes water, to filter and 

 crystallize. 



2. The pure nitrate is to bo decomposed by heat. This ought 

 not to be done in a common earthen-ware retort, because it con- 

 tains too much of the oxides of iron and manganese, but in a 

 perfec Jy white porcelain retort. Four or five pounds of nitrate 

 of barytes may be decomposed at once, and the process will re- 

 quire about three hours. The barytes thus obtained, will con- 

 tain a considerable quantity of silex and alumine, but it will 

 have only very minute traces of manganese and iron, a circum- 

 stance of essential importance. 



3. The barytes, divided by a knife into pieces as large as the 

 end of the thumb, should then be placed in a luted tube of glass. 

 This tube should be long, and large enough to contain from one 

 kilogramme to 1|^ kilogrammes, (from 21bs. 4oz. to 3lbs. 6oz. 

 nearly). It is to be surrounded with fire, and heated to dull 

 redness, and then a current of dry oxygen gas is to be passed 

 through it. However rapid the current, the gas is completely 

 absorbed ; so that when it passes by the small tube which ought 

 to terminate the larger one, it may be concluded that the deut- 

 oxide of barium is finished. It is, however, well to continue the 

 current for seven or eight minutes more. Then the tube being 

 nearly cold, the deut-oxide, which is of a light gray colour, is 

 taken out, and preserved in stoppered bottles. 



4. A certain quantity of water, for example, two decilitres, 

 {A{ pints) is then taken; to which is added as much pure and 

 fuming hydrochloric acid as will dissolve 15 grammes, (232 grains) 

 of barytes. The acid solution is put into a glass with a foot, and 

 ice placed round it, which must be renewed as it melts. Then 

 12 grammes, (185 grains,) of the deut-oxide are to be very 

 slightly moistened, and rubbed, by portions^ in a mortar of agate 

 or glass. As these portions are reduced into a fine paste, they 

 are to be removed by a box-wood knife; and placed in the fluid ; 

 they will soon dissolve without effervescence, especially if 



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