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had been lately acquired for the Institution, was used for the first 

 time at this meeting. 



The last evening meeting, -which brought the session 1869-70 to 

 a close, was held on 27th April, when Mr. Chas. Ekin read a paper 

 on " Ozone and Ozone Tests." Commencing with a consideration 

 of the composition of the atmosphere proper, he stated that the 

 oxygen in it, so all important to our existence, acquires under certain 

 circumstances a greatly increased chemical activity, and becomes 

 ozone, which can always be recognised by its peculiar smell. 

 Discovered by Schonbein in 1840 it is always produced during 

 the process of slow oxidation. It may be made artificially in a 

 variety of ways, as by the discharges in air of a common electrical 

 machine, and is produced naturally during a thunderstorm, as well 

 as by the action of vegetation. • Its chief use in the air apparently 

 being the destruction of organic matter, its presence there seems to 

 indicate the absence of deleterious compounds, and its estimation 

 accordingly aflbrds a relative test of purity. The tests, of which 

 there are two used by meteorologists, are pieces of paper soaked in 

 certain chemicals, which when exposed become more or less dis- 

 coloured according to the amount of ozone in the air. Explaining 

 the application of these tests by several eminent men, he alluded 

 especially to the careful series of experiments by Dr. Daubeny, 

 whereby he concluded that ozone is really disengaged by the green 

 parts of plants dnring their exposure to sunlight. The absence of 

 ozone under the shade of woods corroborates the popular notion 

 that it is unhealthy to live under or in the immediate neighbour- 

 hood of large trees. A comparison of numerous observations made 

 in various countries seems to show that ozone is more abundant at 

 the surface of the ocean and on the tops of mountains, and present 

 more during the N. and E. winds than during S. and W. At Bath 

 Mr. Ekin found, after a careful examination of the register kept by 

 Mr. Russell, that no rule holds good. " As a matter of fact," he 

 said in conclusion, 



" We find that ozone maybe present in the air, that it prohahly is present, 

 though the tests by which we pretend as yet to discover it are very fallacious 

 and unreliable, that it certainly has the property of instantly destroying and 

 being destroyed by organic matter, and that consequently wherever it is 

 present it must have a most purifying influence ; but wiiether this influence 



