vel of the Sea, 118 feet.

Amo'nt of Snow in inches.

Weather, Clouds, Remarks, &c., &c.

[A cloudy sky is represented by 10, a cloudless one by 0.]

Amount of Evaporation. 285 inches.

Rain fell on 11 days amounting to 65 735 inches; it was raining 29
hours 57 minutes and was accompanied by Thunder on 7 days.
Most prevalent wind the S. W. Least prevalent wind the E.
Most windy day, the 23rd day; mean miles per hour, 15:60.

Least windy day, the 5th day; mean miles per hour, 0'06.
Aurora Borealis was visible on I night.

The Electrical state of the atmosphere has indicated constant and high tension.

Ozone was in rather small quantity.

ART. XXVIII.-On Ozone. BY CHARLES SMALLWOOD, M.D., L.L.D., Professor of Meteorology in the University of McGill College, Montreal, Canada.*

Mr. Chairman,

It would be unbecoming in me as forming a part of the deputation to Albany last year, for the purpose of inviting the Association to meet at this place, were I not to take advantage of the present moment, to greet you, gentlemen Members of the American Association, with a cordial and hearty welcome, and I need scarcely add, that the like sentiment inspires the whole of the inhabitants of this city.

Until the present time, these Annual Meetings have been confined to the United States alone, (although not exclusively American,) and separated only by an imaginary boundary, which has now been removed, for we here meet, united as one family, having one common object in view," the Advancement of Science,"

This and the following paper were read at the Annual Meeting of the American Association for the Advancement of Science, Montreal, August, 1857.

we are treading the same peaceful path of knowledge, we are assembled under the broad, the vast canopy of the American firmament, the gentle breeze that wafts the red cross banner of St. George and Merry England, alike unfurls, the stars and stripes, the emblem of your land of freedom. Long may these two flags entwine in peace, in kindred folds, and may that master-piece of scientific genius, the electric cable, which is at this moment being laid beneath the Atlantic sea, whose waves science has measured with a mighty span, be the peaceful band, that will cement more firmly the destinies of the two great nations of the earth, under the benign and able guidance of your worthy President, and our beloved Queen, and may science, which knows no country, no nation, no language, be rendered more subservient to the happiness and welfare of the whole human family.

A year has now passed since the deputation from this place enjoyed the hospitalities of one of your large cities, the familiar and friendly faces of many we met there, and now present, calls to mind many pleasant recollections, but like all things mundane, we have some cause for sadness, for in the few fleeting moons that have waned since last we met, death has taken from our midst a Redfield, a Bailey, and a Mitchel, each pre-eminent in his department of scientific research, and to science and us, an irreparable loss, and the Association has done itself honor in paying a tribute to their memories; but the midnight lamp of the man of science must grow dim, the experimentalist must for ever quit the busy scenes of his laboratory, the eye of the astronomer must be closed, for the life of the philosopher is but mortal.

It is my intention to lay before the section the results of observations made on the amount of ozone present in the atmosphere. The place of observation is at St. Martin's, about 9 miles due west of Montreal, and is 118 feet above the mean level of the sea; it is situated in the centre nearly of the Isle Jesus, an island surrounded by the branches of the Ottawa, the place of observation is a little more than 3 miles from the river, thus being sufficiently inland, to be removed from any transient vapour or fog, which is often present in the proximity of rivers; it is a flat island, and the whole of the neighborhood is under cultivation.

It is not my purpose to enter into a lengthy detail of the chemical composition of ozone, enough for our present purpose to define it to be, a compound of oxygen, analogous to the per-oxide of hydrogen, or that it is oxygen in an allotropic state, that is

with the capability of immediate and ready action impressed upon it. To Schonbien is awarded the discovery, who, in 1840, applied the term ozone to the peculiar smell which is perceptible during the action of the electrical machine, and also during the decomposition of water by the galvanic apparatus. It was subsequently ascertained that a similar smell is developed by the influence of Phosphorus on moist air, and also by a great many chemical changes, and for some time its existence was recognized by its smell, or odour, alone; but in April, 1848, Schonbien became possessed of another of its characters, viz: its oxidizing principle, and it is this property which it possesses more particularly, when we direct our attention to its presence in the atmosphere, although these oxidizing properties may be common to some other bodies, as nitrous acid, which is said to be generated in the atmosphere by atmospheric electricity.

When largely diffused in the atmosphere, it causes like chlorine (to which it is somewhat allied) very unpleasant sensations, such as difficult respiration, and it acts powerfully on the mucous membrane, it kills small animals very quickly; it is insoluble in water, and oxydizes very quickly all metallic bodies, and it has the power in a large degree, of destroying miasma arising from the decomposition of animal and vegetable substances, and Schonbien came to the conclusion, that its formation depended upon the action or formation of atmospheric electricity, and he referred the beneficial effects of thunder storms, to the action of the ozone formed, neutralizing the miasma arising from the decomposition of animal and may be vegetable substances, and it possesses in a powerful degree bleaching properties, and in this it is again analogous to chlorine.

Since Schonbien brought its properties before the scientific world, it has received more or less attention both from the physi cian and the meteorologist.

It has been advanced, that during the presence of cholera and other epidemic disease, its absence was remarked, while on the other hand, when the atmosphere has indicated a great amount present, diseases of the lungs and mucous membrane have been more prevalent, it has been still further stated that its action on the vegetable kingdom is similar in its effects as in the animal economy; the potatoe disease or rot especially, and other diseases in vegetables has, it is said, been caused by either its absence or presence, in too large quantities.