EARTHS. 269 



(d.) In air, becomes covered with a film of baryta, and in water un- 

 dergoes the same change; effervesces violently and evolves hydro- 

 gen. If gently heated in air, it burns with a deep red light and be- 

 comes baryta. 



(e.) Sinks in water, and even in sulphuric acid, although surround- 

 ed by gas ; hence its sp. gr. cannot be less than 2, probably over 3. 



(/.) Flattened with difficulty by pressure. 



(g.) Constitution of the protoxide, about 89.75, metal, 10.25 

 oxygen=100.00. Barium, 1 proportion, 70, oxygen, 1 proportion, 

 8=78. 



(h.) PEROXIDE OR DETJTOXIDE. Baryta, prepared by ignition of 

 the nitrate, is placed in fragments as large as a hazel nut, in a coated 

 glass tube, and heated to low redness, when it rapidly absorbs dry 

 oxygen gas as it is passed over it and becomes peroxide with prob- 

 ably two proportions of oxygen ; it is formed also by heating ba- 

 ryta in contact with oxygen or common air resting upon it, but in the 

 latter case some carbonate is also formed. Concentrated barytic 

 water becomes filled with pearly plates of the deutoxide of barium, 

 when oxygenized water, containing ten or twelve times its volume of 

 oxygen is poured into it. Thenard. 



Composition of the peroxide. Barium, 70, oxygen, 2 proportions, 

 16 = 86; the peroxide contains twice as much oxygen as the pro- 

 toxide. 



It has been found that the nitrate of baryta may be decomposed 

 by heat with such care, that the deutoxide is left ; it is done in a lu- 

 ted porcelain retort, connected by a Welter's safety tube with an in- 

 verted jar of water. The heat is gradually raised to redness, as long 

 as nitric oxide or nitrogen gas is disengaged, and when they cease 

 and pure oxygen comes, it is a proof that all the nitrate is decompos- 

 ed, and then the deutoxide will remain in the retort. Turner. 



(i.) The deutoxide of barium is scarcely sapid, it is grayish white, 

 loses its excess of oxygen by an intense heat, and acts with the aid 

 of the same agent upon various combustible bodies, and thus becomes 

 a protoxide. In contact with hydrogen near a red heat, there are 

 luminous jets from the surface of the deutoxide, but the water that 

 is formed is all retained in the state of hydrate, and the baryta thus 

 becomes very fusible. Boiling water causes the excess of oxygen 

 to escape in the form of gas. 



(/.) This substance was employed, (July, 1818,) by Thenard, for 

 the oxygenation of water.* 



Baryta is poisonous ; its natural carbonate is employed in Lan- 

 cashire, (Eng.) as a ratsbane. 



* See this work, p. 215, and Henry, Vol. I, p. 264, 10th Lond. Ed. ; also, Ann. dc 

 Chim. et de Phys. VII. IX ; Ann. of Philos. XIII, XIV, XV, and Quarterly Eng. 

 Jour, of Science, VI. 150, 379, VIII. 114, 154. 



