472 THE MOUNTAIN. 



is viewed as the great purifier of the atmosphere."* This 

 principle in the air has been the subject of much specula- 

 tion, but its laws of action and special sanitary qualities 

 are still conjectural, and " although the constant existence 

 of the principle in the open air of the country and the 

 sea is ascertained, the proportions in which it exists in 

 different localities is found to be subject to great varia- 

 tion, "f 



Dr. Charles Srnallwood, of St. Martin, Isle Jesus, Canada 

 East, the accomplished professor of meteorology in the Uni- 

 versity of McGill College, Montreal, has been making con- 

 stant observations on ozone for twelve years. His contri- 

 butions in this department of science are of a most interesting 

 character, and as he is one of the extremely few observers 

 on the continent, his labor possesses great value. His publi- 

 cations may be found in the " Transactions of the American 

 Association," for 185*7, also in numbers of the "Canadian 

 Naturalist and Geologist," 1859. In a letter recently re- 

 ceived from Dr. Srnallwood, he says : 



"I use the formula of Schonbein; but instead of paper I find 

 calico or fine muslin, soaked in the solution of starch and iodide of 

 potassium, better than paper, and I am now observing the constant 

 variations of the amount by an instrument that is worked by clock- 

 work, and keeps constantly moving the prepared test one inch per 

 hour. I wish to ascertain the connection of ozone with the usual 

 barometric fluctuations, and also with the humidity of the atmo- 

 sphere. I have also subjected the tests to different colored rays of 

 light, and also to polarized light ; and I have also investigated the 

 effects of vegetation on its amount. 



"The daily continued observations are taken at ten P.M. and six 

 A.M., at the height of five feet from the surface of the soil ; besides 

 this, I have observed at an altitude of eighty feet above the ground, 

 and in all possible situations on the ground, between the rows of 

 vegetables, potatoes, Indian corn, etc. 



"I would very concisely sum up thus : 



"Ozone does exist in the atmosphere; varies in quantity ; moist 

 weather favors its development ; northeast and southeast winds 

 favor its development ; snow and rain also increase its amount ; and 



*.British and Foreign Medico-Chirurgical Review, 1852. 

 t Francis, " Change of Air." 



