COMPOSITION OF OXIDE OF ZINC. 57 



muriate of barytes are exposed to a red heat, 

 they lose 2-25 grains of their weight, and are 

 converted into 13-25 grains of chloride of ba- 

 rium. When 13-25 grains of chloride of barium 

 are dissolved in water, the solution contains just 

 9*75 grains of barytes. Now, 9*75 represents 

 the atomic weight of barytes, which requires for 

 saturation exactly 5 of sulphuric acid. And 

 14*75 parts of sulphate of barytes contain just 

 5 parts of sulphuric acid. 



A little distilled water was put into two small 

 cylindrical glass jars, and 18-125 grains of 

 crystallized sulphate of zinc were dissolved in 

 the one of these, and 13-25 grains of chloride 

 of barium in the other. The two liquids being 

 mixed, a double decomposition took place, and 

 sulphate of barytes precipitated in the state of 

 a white powder. This precipitate being col- 

 lected, washed, dried, and heated to redness, 

 weighed 14*75 grains, and therefore contained 

 exactly 5 grains of sulphuric acid. A few 

 drops of the colourless liquid from which this 

 sulphate had precipitated, were put into a watch 

 glass, and a small quantity of muriate of barytes 

 mixed with it ; but it did not become in the 

 least muddy or even opal coloured, showing that 

 it contained no sensible quantity of sulphuric 

 acid. For I find that 1 grain of glauber salt 

 (containing 0-2469 grain of sulphuric acid) dis- 

 solved in 12,000 grains of water, is sensibly 



