216 WATER. 



baryta, and finally by concentration by air pump exhaustion, aided 

 by the affinity of the vapor of water for sulphuric acid. 



3. PROPERTIES. 



(a.) They are remarkably different from those of water. The 

 fluid is colorless and inodorous ; destroys gradually the color of litmus 

 and turmeric paper ;* is somewhat corrosive to the skin, bleaches it, 

 and if abundantly applied, destroys it. It bleaches the tongue, 

 makes it tingle, and gives a peculiar taste resembling that of metallic 

 solutions. 



(b.) Although much more fixed than water, it may be entirely evap- 

 orated in a vacuum, without decomposition. At 59 Fahr. it is de- 

 composed into water and oxygen gas. It can therefore be scarcely 

 preserved except surrounded by ice ; but it remained fluid at every 

 degree of cold applied to it. 



(c.) At 212, it is decomposed explosively, oxygen gas being lib- 

 erated, and therefore if we would decompose it by heat, it must be 

 previously diluted. Diffuse day light has no effect upon it, and di- 

 rect solar light very little. 



(rf.) It is decomposed by nearly all the metals, and by most of their 

 oxides, these substances being in a state of minute division. 



(e.) Those that powerfully attract oxygen combine with a portion 

 of it; such are potassium, sodium, arsenic, zinc, &ic. and in this way 

 several metallic protoxides become peroxides, and on the same prin- 

 ciple hydriodic acid, sulphurous acid and sulphuretted hydrogen, at- 

 tract oxygen from this fluid and bring it to the condition of water. 



(/.) Oxide of silver]- decomposes the oxygenized water with ex- 

 plosion. This happens if the fluid falls on the silver, drop by drop, 

 and if the place be dark, light is seen. 



(g.) Several other peroxides decompose this oxygenized compound. 

 Such are those of manganese, cobalt, lead, platinum, gold, iridium, 

 rhodium, and palladium ; the oxygen of the water is always disen- 

 gaged, and sometimes that of the oxide. The decomposition is 

 complete and instantaneous, and sometimes ignition is produced in 

 the glass tube containing the materials. 



* Some have supposed that the bleaching powers of chlorine may depend on the 

 mixture with it, of a small quantity of oxygenized water. 



t In the Am. Jour. Vol. XVII, p. 34, Dr. Ed. W. Faust has suggested, that this 

 curious phenomenon of the decomposition of oxygenized water by oxide of silver, 

 may be accounted for upon galvanic principles : thus 



"When any metal is placed in the peroxide of hydrogen, a galvanic effect is pro- 

 duced. The hydrogen having less affinity for the excess of oxygen, than the metal 

 has, the liquid becomes negative, thus acting the part of the copper plate of a bat- 

 tery, while the metal becomes positive, supplying the place of the zinc plate. The 

 liquid is thus resolved into water and oxygen. If the metal be very oxydable, it 

 retains the oxygen, which is evolved if gold, platina, &c. be used. We need scarce- 

 ly refer to the wires of a battery, for a parallel case. 



" When the peroxide of hydrogen conies in contact with the oxide of silver, the 

 oxygen escapes from both, and the latter is reduced to the metallic state." Far a 

 fuller account, see the paper of Dr. Faust. 



