142 WHITE VITRIOL. 
than white lead, is prepared from it. Dyers use a con- 
siderable quantity of white vitriol to render deeper the 
colours produced by madder, cochineal, and other sub- 
stances. 
A pleasing experiment is made by mixing in a phial 
a small quantity of solution of white vitriol with a little 
liquid ammonia. Though each of the fluids is transpa- 
rent when separate, yet the zinc will now be immedi- 
ately precipitated in a white mass ; and, what is peculi- 
arly deserving of remark, if then shaken, it will almost as 
instantly be re-dissolved. 
