NOTICE OF SCHOENBEIN. 191 



its oncrg'etic action on the caoutchouc tubes tlivou£>-b wliicli it is conducted. It 

 bleaches most vegetable cxdors; it changes the black sulphide of lead into white 

 sidphate, the yellow ferrocyanide of potassium into the red feirocyanide. It oxy- 

 dizes moist filings of iron, copper, mercury, and silver. In some cases, however, 

 ozone acts as a deoxydizing agent. It decom})oses peroxide of iron and barium. 

 It exists in variable quantities in the atmosphere, and its presence is indicated 

 by what is called ozone test-paper, namely, pa])er steeped in iodine of potassium, 

 which is rendered brown by the liberation of the iodine. If starch be added to 

 the solution in which the paper is steeped the ozone produces a blue color; but 

 according to some authorities this test is not as reliable as that of the solution 

 of the iodide of potassium alone. As ozone is an energetic oxydizing agent, it 

 combines with animal matter and other impurities in the air, and hence its 

 absence, as evinced by the want of coloration in the test-paper, is considered as 

 an indication of the presence of malaria in the atmosphere of the locality in 

 which such indications are observed. It is evident from what has been stated 

 that ozone must 1)0 produced in the atmosphere by electrical discharges, but 

 whether it exists from other sources in the air is at present unknown. Neither 

 are the test-papers we have mentioned decisive proofs of its relative quantity, 

 since there are other substances generally present in the air which are competent 

 to produce similar efl'ects. 



One of the most plausible hypotheses as to the nature of ozone is that of Clau- 

 sius, who considers all gases, whether simjile or compound, as made up of a num- 

 ber of atoms combined together to form molecules. That, for instance, a mole- 

 cule of oxygen consists of at least two atoms, and that it may happen that a 

 portion of each of the great number of molecules which exists in a given quantity 

 of oxygen can be decomposed into two atoms which distribute themselves in 

 their separate state among the remaining undecomposed molecules, and that 

 these isolated atoms, which in their relations to foreign bodies must differ from 

 the molecules of ordinary oxygen, constitute ozone. 



In accordance with this hypothesis, the production of ozone by passing elec- 

 tricity through oxygen or atmospheric air may be attributed simply to the repul- 

 sive poAver of the electricity by virtue of which the two atoms of oxygen, beiug 

 charged with the same kind of electricity, are driven apart, as in the case of the 

 well known experiment of two pith-balls. When oxygen is evolved in the 

 decom}X)sition of water, a similar repulsive separation takes place at each polo 

 or electrode, but most of the atoms immediately combine again upon the elec- 

 trodes to form ordinary oxygen. A small i)ortion only of the atoms remain in a 

 separate condition, and these constitute the ozone with which the oxygen is 

 niix(>d. Finally, in the case in which ozone is developed diu'ing the oxidation 

 of phosphorus in nioist air or oxygen, we may suppose that the atoms which 

 make up the oxygen molecules are in dilierent states or degrees of electricity ; 

 that one of these tends more energetically to coml)ine with the phosphorus than 

 the other; and that the latter, removed from the sphere of its attraction by 

 the heat generated in the combination of the former, remains in an isolated con- 

 dition. The fact that these atoms do not innnediately recombine into molecules 

 to form ordinary oxygen may be due to their similar eh^ctrical state. When 

 ozonized air is heati^d, the ozone disappears, because the high temperature deter- 

 mines the union of the atoms as it does of hydrogen and oxygen in the 

 a]»plication of a flame to a mixture of these two gases. It has been found 

 that the ozonification of oxygen by the electrical spark or brush can only be 

 carried on to a certain extent if the ozone remain mixed with the oxygen ; but it 

 the ozone be removed as ra))idly as it is formed by the oxidation of silver, all 

 the oxygen may l)e gradually converted into ozone. In this case, when the 

 number of se])arate atoms l)ecome too great in a given sjiace, they are brought 

 within the sphere of mutual attraction; combination ensues, and the ozone dis- 



