The quality of Canadian kerosene has been greatly improved of late years, but notwithstanding the elaborate process of refining, the oil, though thoroughly deodorized and of good color, contains sulphur, and of course evolves sulphur compounds in its combustion. The rules of the Petrolia Oil Exchange provide that refined kerosene shall be of the odor "locally known as inoffensive," and shall "absolutely stand the test of oxide of lead in a strong solution of caustic soda without change of color." The "burning percentage" in the case of "Extra Refined Oil," "Water White" in color, and of specific gravity not exceeding 0.800, is required to be not less than 70; in the case of "No. 1 Refined Oil," "Prime White" in color, not less than 60; and in the case of "No. 2 Refined Oil," "Standard White" in color, to be not less than 55. The "burning percentage" is determined by the use of a lamp thus described: "The bowl of the lamp is cylindrical, 4 in. in diameter and 23/4 in. deep, with a neck placed thereon of such a height that the top of the wick tube is 3 in. above the bowl. A sun-hinge burner is used, taking a wick 7/8 in. wide and 1/8 in. thick, and a chimney about 8 in. long." The test is conducted as follows: "The lamp bowl is filled with the oil and weighed, then lighted and turned up full flame just below the smoking point, and burned without interference till 12 oz. of the oil is consumed. The quantity consumed during the first hour and the last hour is noted." The ratio of the two quantities is the measure of the burning quality, and the percentage that the latter quantity is of the former is the "burning percentage" referred to. * * * * * TREES FROM A SANITARY ASPECT. BY CHARLES ROBERTS, F.R.C.S., ETC. As this is the usual time of the year for planting, pruning, and removing forest trees and shrubs, it is a fit time for considering the influence which trees exert on the sanitary surroundings of dwelling places. The recent parliamentary report on forestry shows that trees are now of little commercial value in this country. And we may conclude, therefore, that they are chiefly grown for picturesque effect, and for the shelter from the sun and winds which they afford.