304 



On Chemical Tests; 



[Oct. 



luble while the carbonic precipitate is soluble in weak muriatic, or nitric 

 acid. Suppose sulphate of potash and carbonate of potash to exist 

 together in solution; on adding any one of the baryta tests, a white 

 precipitate will fall of sulphate, and carbonate of barytes mingled toge- 

 ther. They may be separated and their weights ascertained thus. 

 Wash the precipitate with pure water, dry, and weigh it. Then add 

 dilute muriatic or nitric acid, and the carbonate of barytes will dissolve 

 with effervescence; the sulphate will remain untouched. The sulphate 

 washed, and dried, will give its own weight, and the difference between 

 the weight of the sulphate, and the original weight, will be the weight 

 of the carbonate. 



a. Solution of barytes, or barytic water is made by dissolving pure 

 baryta in distilled water. It may be employed to separate baryta from 

 strontia in a neutral solution ; the baryta having a stronger affinity for 

 acids will be taken up, and the strontia will be precipitated. As barytic 

 water soon spoils, it should be used fresh. 



b. Baryta and its combinations are poisonous. A considerable num- 

 ber of its salts are insoluble in water. 



c. Baryta in solution is distinguished from the alkalies by its pro- 

 ducing a white precipitate with carbonated alkalies, and with dilute 

 sulphuric acid. 



d. To distinguish barytes from strontia, dip a piece of paper in the 

 solution. Barytes burns yellow ; strontia red, see 115 c. To distinguish 

 barytes from lime, see 44, 72 d, and 79 d. 



e. Baryta, acting on carbonic acid, is of course equally acted on and 

 decomposed by the carbonated alkalies : but in this case their precipi- 

 tate as before shown in this article is soluble with effervescence by 

 dilute acid, either nitric or muriatic. Both the nitrate and muriate of 

 baryta are soluble in water, the sulphate is not. 



f. It has been remarked by Berzelius, that when sulphuric acid is 

 precipitated from some of the weaker bases by a barytic salt, the preci- 

 pitated sulphate of baryta is combined with a portion of those bases. 

 Thus when sulphate of iron or copper is decomposed by muriate of 

 baryta, the sulphate of baryta, when dried and calcined, assumes a red- 

 dish colour in the first case, or a yellowish green in the second. In order, 

 therefore, to determine with precision the quantity of sulphuric acid, 

 it is necessary to remove the excess of oxide by some acid in which it 

 is soluble. 



g. By the cautious addiiion of acetate of baryta, as long as it occa- 

 sions any precipitate, all the sulphates existing in any solution are de- 

 composed, and their bases are obtained united witn acetic acid. By 

 evaporating the liquid to dryness, and calcining the residuum, the ace- 



