BARYTIC SALTS DECOMPOSED BY SODA. ^g 



is unquestionably the mos.t simple method of procunng in » tammg pwre 



, . , - - , 1 ri ^t • barytej in the 



laboratory the biirytes that may be wanted, tor this pur- large way vith 



pose ahaiidred parts of sulphate of barytes accurately mixed successu 

 with twenty parts of charcoal powder are to be calcined by 

 a strong heat in close vessels. After being exposed to a 

 high heat for an hour, the crucible is to be suffered to cool ; 

 the residuum separated and diluted in water; and a suffi- 

 cient quantity of nitric, muriatic, or acetous acid added, 

 llie mixture is to be heated gently, when it will give out a 

 large quantity of sulphuretted hidrogen and carbonic acid, 

 which must be guarded against with care. When the effer- 

 vescence ceases, and test paper indicates a slight excess of 

 acid in the liquor, it is to be filtered and evaporated, to de- 

 compose the sulphuretted hidrogen, and precipitate the sul- 

 phur, that was retained in solution*. The residuum is to 

 be redissolved in the least water possible, and a saturated 

 solutionof caustic potash is to be added. At the instant of 

 mixture a large quantity of crystals of barytes falls down. 

 Tlie whole being left at rest in as low a temperature as pos- 

 sible for an liour or two, the mother water is to be poured 

 off; the crystals are to be washed with a little distilled water, 

 and then dried by pressing them between folds of blotting 

 paper ; and lastly they are to be dissolved in as much boil- 

 ing water as is necessary. This solution, being filtered, will 

 let fall when cold the barytes, which is much more pure, and 

 costs less, than when obtained from the decomposition of 

 nitrate of barytes by heat alone. 



It is to be observed, that the muriatic or acetous acid is Muriatic or 



^referable to the nitric, because each forms a more soluble f^^'^"^ ^'^^^} *• 

 ^ ... be ijreterred. 



salt than the nitric, and the washing is more easy ; and be- 

 cause in making the solution the nitric acid is partly decom- 

 posed, and oxigenizes a portion of the sulphuret of barytes, 

 so that soniQ^of the acid is lost, and some of* the barytes ub- 

 feorbed by the sulphuric acid formed. 



The caustic potash used in this process must be prepared The potash 

 from carbonate perfectly free from sulphate. ^'^ ^^/^Z^ 



* The same object may be attained more readily by pouring into the 

 liquor a few drops of solution of nitrate of copper or lead, letting the me- 

 taliVo sulphuret subside, filtering afresh, &g. 



Observathn 



