330 SALTS SULPHATES. 



results, and carbonate of baryta and sulphate of alkali remain mixed 

 in the crucible ; wash out the soluble sulphate with water, dissolve 

 the carbonate of baryta in muriatic acid ; decompose it by the car- 

 bonate of an alkali, and thus, after strong ignition, especially in con- 

 tact with charcoal powder, the pure earth will be obtained. 



(d.) Native carbonate of baryta dissolves in sulphuric acid, with 

 a very slow and scarcely perceptible effervescence. 



7. USES. 



(a.) To afford baryta by its decomposition, and for the prepara- 

 tion of a phosphorescent substance. 



(b.) It has been used in the manufacture of porcelain, particularly 

 by the late Mr. Wedgwood.* 



(c.) The artificial sulphate, under the name of permanent white, is 

 applied in painting in water colors, and is the most delicate and per- 

 manent white known, f The carbonate is employed for the same 

 Qose. Either of them may be used with advantage in labelling 

 es in a laboratory, where acid vapors are so apt to destroy 

 common writing ink.J 



[d.) The sulphate of baryta is the only salt of this earth that is not 

 poisonous. If the carbonate, which is a virulent poison, has been 

 swallowed, diluted sulphuric acid would therefore be an antidote ; 

 and if any soluble salt of baryta has been taken, a solution of sulphate 

 of soda or other alkaline or earthy sulphate would be the best remedy. 



SULPHATE OF STRONTIA. 



1. DISCOVERY. By Dr. Hope and Mr. Klaproth, about the year 

 1793. 



2. NATURAL HISTORY. 



(a.) Exists naturally in considerable abundance ; usually called ce- 

 lestine, from a delicate tinge of sky blue, which it frequently has ; 

 first observed at Strontian, in Scotland ; found at Bristol, England ; 

 at Bouvron, France, and at Montmartre, near Paris ; in splendid 

 crystals in Sicily ; also very beautiful at Put-in-Bay, Mackinaw, and 

 Detroit, on the Great Lakes, and at Lockport, N. Y. 



(b.) Found crystallized, massive, or in veins, "composed of nee- 

 dles, or very fine rhomboidal prisms;" sometimes foliated, fibrous, or 

 granular ; occasionally in sulphur beds. 



* He employed it in what was called the jasper ware, which, for a long time, was 

 made by Mr. Wedgwood alone ; but the secret having been discovered and sold by 

 a faithless servant, both the price and beauty of the vessels were soon much re- 

 duced by inferior artists. Parkes* Essays, Vol. I, p. 317. t Parkes. 



t Artificial sulphate mingled with lampblack, painter's oil and spirits of turpentine, 

 for light colored bottles, drawers, &c. without the lampblack, for black bottles, &c. 



c.u. s. 



Thenard, Vol. Ill, 172, says, " Le sulfate de bavyte est employe en Angleterre 

 eomme mort-aux-rats." This appears to be a mistake; th carbonate is the sub- 

 stance actually used for this purpose. 



