OZONE DISTINCTIVE CLIMATES. 31 



The usual mode of gauging the amount of ozone present in 

 the air is to expose test slips made of blotting paper soaked in 

 a solution of iodide of potassium and starch. The slips are 

 suspended in a little cage, roofed in so as to shelter them from 

 the rain and the direct rays of the sun, and the degree of 

 discoloration that takes place in a definite time is then care- 

 fully noted and compared with a fixed scale. The results of 

 such tests are, however, not trustworthy, as no account is 

 taken of the varying wind force, a most important factor in 

 making a correct estimate. Besides, nitric acid, peroxide of 

 hydrogen, and other agents occasionally present in the atmos- 

 phere, may exert a similar action upon the iodide of potassium, 

 and be thus partly or wholly responsible for the production of 

 the iodide of starch colour. Mr. Baxendell gave some inter- 

 esting lectures in 1881 upon the results of his tests for ozone, 

 extending over nine years. They were made at the Observa- 

 tory in Hesketh Park, where he had the advantage of com- 

 paring the wind force and direction at the same time. His 

 tables show that the amount of ozone in the Southport air is 

 large, and also that it has increased since the sanitary condition 

 of the town has been improved. 



Southport having two water lines, at a great distance apart, 

 the climate of each has its own distinctive quality ; that at 

 high-water mark having all the characters of the stronger and 

 more stimulating one at low-water, but in a more modified and 

 milder form. Beyond this inner line, and more in the line 

 of the streets of the town, the sea breeze is found still more 

 softened, the atmosphere is buoyant and remarkably free 

 from impurity and humidity. Invalids being able to avail 

 themselves of the varied qualities of these distinct climates 



