PHYSIOLOGICAL INFLUENCE OP OZONE HILL AND FLACK. 619 



the electrical discharge of high-potential currents across shoots of 

 fine gauze set parallel and insulated from each other. The gauze net 

 insures the equality of the discharge over the whole surface, and pre- 

 vents that excessive high-tension discharge at certain rough points, 

 which occurring in the older form of instruments fitted with smooth 

 metal plates, causes the production of oxides of nitrogen from the 

 burning of atmospheric nitrogen. 1 Our object therefore has been to 

 determine the effects of undoubtedly pure ozone, especially in con- 

 centrations far less than those used by previous observers. 



Method of estimation of concentration of ozone. — The air containing 

 ozone is sucked by an aspirator or filter pump through a 1 per cent 

 solution of potassium iodide, acidified with a small quantity of 10 

 per cent sulphuric acid contained in a Drechsel wash bottle. It is 

 essential that contact with rubber be avoided. After 10 liters of air 

 have been passed through the wash bottle, the acidified KI is removed 

 and freshly prepared pure starch emulsion added. A blue color indi- 

 cates the presence of ozone. The amount is estimated by titration 

 with sodium hyposulphite solution until this blue color is discharged. 

 The hyposulphite solution is prepared by dissolving 22.2 grams in 

 in 1 liter of distilled water, so that 1 c. c. of the solution is equivalent 

 to 100 parts per million of ozone in the air collected as a 10-liter 

 sample. For small quantities of ozone the solution may "be diluted 

 10 or 100 times, giving 1 c. c. of the solution, equal, respectively, to 

 ten parts and one part per million of ozone in the air collected. 



Lethal dose of ozone. — To determine this the animals were placed in 

 a large air-tight chamber. The ozonized air was then driven through 

 by means of a gas engine driving an air pump, and the concentration 

 of ozone determined in the issuing air. The animals could be observed 

 through the glass windows of the chamber, which could also, if neces- 

 sary, be lighted by electric light. Our experiments show that ani- 

 mals may die after being submitted to 15 to 20 parts per million for 

 two hours. We do not doubt that a lower concentration would have 

 a fata], effect if breathed for a much longer period. 



The cause of death is acute inflammation of the respiratory tract. 

 The lungs become intensely congested and cedematous. Microscopic- 

 ally the pulmonary alveoli appear full of an inflammatory exudation. 

 Many of the alveoli are full of blood, for so intense is the irritant effect 

 that hemorrhages take place. There are no other signs of the effect 

 of ozone in the body. On inhaling ozonized air ourselves and expir- 

 ing through the iodine test solution we find no evidence of ozone in 

 the exhaled air. It is all taken up by the wet mucous surface of the 

 respiratory tract and exerts its effect there. 



1 Mr. Edward L. Joseph, the inventor of the "Ozonair" apparatus, was good enough to give us the use 

 of a complete installation and place his information at our disposal. 



