CHEMISTRY. 201 



has now redetermined it by moans of Graham's law, that the 

 44 velocity of diffusion of a gas is inversely as the square root of its 

 density." He ascertained the coefficient of diffusion of chlorine 

 into oxygen, and of ozone into oxygen. He found that in 45 

 minutes for every cubic centimeter of chlorine contained in one of 

 the two diffusion tubes, '0.227 of chlorine diffused into the upper 

 tube, while for ozone the quantity under the same circumstances 

 was 0.271. Now the ratio .227 to .271 = .8382 : 1 ; and if we as- 

 sume ozone to have Ik times the density of oxygen, Graham's 

 law would give us */35.5 : x /24==l : .8222, a remarkably close 

 approximation, considering the difficulties of the method. We 

 may, therefore, fairly regard the density of ozone as 1 times that 

 of oxygen, or 1.G57, if air be taken as 1, and 24 if hydrogen be 

 unity. While, therefore, the molecule of free oxygen contains 

 2 atoms, that of ozone contains 3. 



According to the experiments of Dr. Daubeny, the quantitative 

 estimation of ozone by means of Schonbein's and Moffat's paper 

 is rendered very uncertain in consequence of the action of light 

 on the papers ; both are quickly acted on by direct sunlight, and 

 yet such papers maybe seen exposed to full sunlight at the offices 

 of important public departments, and the results are given as the 

 action of ozone. To get strictly ozonic effects, the papers must 

 be protected from direct sunlight : diffused light seems to promote 

 the action of ozone on the paper. The source of ozone (not the 

 only one, however) Dr. Daubeny finds to be the respiration of 

 growing plants, which is abundantly proved by his experiments; 

 and he therefore concludes that vegetable life counteracts the in- 

 jurious effects of the animal creation on the air we breathe, not 

 only by restoring to it the oxygen which the latter had consumed, 

 but also by removing, through the agency of the ozone which it 

 generates, the noxious effluvia arising from the processes of putre- 

 faction and decay. 



M. Schonbein has recently discovered that ordinary oxygen is 

 without action upon the protoxide of thallium, while ozonized 

 oxygen combines rapidly with it, forming the peroxide of thal- 

 lium, of a brown color. Did not the carbonic acid of the air 

 transform this oxide into carbonate, which passes more slowly to 

 the state of peroxide, paper, steeped in a solution of oxide of 

 thallium and exposed to free air, would be an excellent ozonome- 

 tric paper. 



Our knowledge regarding the different conditions in which oxy- 

 gen may exist is constantly receiving new accessions. Not the 

 least important of these is the fact, recently discovered, that the 

 oxygen in the peroxide of manganese is in a very different condi- 

 tion from that in the peroxide of barium, a circumstance which is 

 strongl v confirmatory of the theory of Schoubein, that oxygen may 

 exist in two opposite states, which are termed ozone and antozone, 

 oxygen in its ordinary state being a combination of both. It 

 lias been proved by recent researches that the oxygen in the per- 

 oxide of barium is in the form of ozone, and that in the peroxide 

 of manganese in the form of antozone. The consequences which 

 follow from these discoveries are of a most interesting description, 



