Chloride of Barium and Nitrate of Lead. 277 



tain precautions, from part of the potassa precipitating with 

 the barytes. 



(A.) Sulphate of soda of commerce being purified by re- 

 peated crystallization, some of the clearest and most regular 

 crystals were melted, dried, and heated to redness for half an 

 hour. 



(B.) Oxalic acid was saturated with carbonate of ammonia, 

 both of commerce. 



(C.) Nitrate of lead was similarly prepared with nitric acid 

 and ceruse ; and both these salts purified also, by repeated cry- 

 stallization, and selection of the crystals, were dried between 

 folds of tissue paper in a current of warm air. 



(D.) Chloride of barium was in the same manner prepared 

 by neutralizing muriatic acid with common carbonate of ba- 

 rytes. Sulphuret of barium (sulphate ignited with charcoal) 

 was added, and afterwards caustic barytes (carbonate similarly 

 treated), till the liquid aifected turmeric paper strongly. The 

 salt was then crystallized, powdered, boiled in pure alcohol 

 and digested therein for a night; redissolved in distilled wa- 

 ter and subjected to a current of carbonic acid ; recrystallized 

 and heated to redness for half an hour, avoiding fusion, by 

 which the salt had on a former occasion become alkalescent 

 (perhaps from impurity, as it was differently prepared). 



(1.) 13j grains of this chloride were precipitated by 9 grs. 

 of sulphate of soda: the former weighed with every precaution 

 against absorption of moisture ; the solutions mixed hot; and 

 the phial immediately placed in the sand-bath, where it con- 

 tinued for three hours. The clear supernatant liquid when cold, 

 tested with its original ingredients, remained at first perfectly 

 clear with each ; but after a few minutes a slight opalescence 

 appeared with the sulphate of soda ; and in time, a very small 

 quantity of precipitate subsided. I could not collect this sa- 

 tisfactorily, and the estimate of -05 gr. for the quantity which 

 might have been obtained from the whole solution, does not 

 pretend to accuracy. The first precipitate weighed, after 

 heating red, U-68 grs.; and there was an opacity about the 

 sides of the phial in which the solutions had been mixed. 



(2.) 20 J grs. of nitrate of lead were precipitated by 8| grs. 

 of oxalate of ammonia ; the solutions being mixed warm. 

 The clear litjuor remained perfectly transparent when tested 

 with its original constituents in every way. 



In checking these experiments by alternation of the in- 

 gredients, i.e. chloride of barium with oxalate of ammonia, 

 and nitrate of lead with sulphate of soda, the result was not 

 the same. 



Oxalate of ammonia is a delicate substance to dry. Whether 



it 



