Wintergreen oil is also obtained by distillation from _Gaultheria punctata_ and _Gaultheria leucocarpa_. An oil, very closely resembling wintergreen oil, is in this country distilled from the young shoots of the American species of birch, _Betula lenta_, variously called sweet birch, black birch, cherry birch, and mountain mahogany. According to Procter, the oil does not exist in the birch but is formed by the action of the water upon an odorless body, called gaultherin, which is converted into volatile oil by the reaction of another substance analogous to emulsin. Hence the formation of oil is similar to that of oil of bitter almonds. To obtain the oil from _Betula lenta_, the material is chopped up and placed in the still, as much as this will hold, a sufficient quantity of water being then added to fill the still about one-third full. The still is generally permitted to remain in this condition over night, a fire is made in the morning and distillation proceeds nicely. The manufacture of birch oil is carried on at quite a large scale by Mr. A. H. Seidle, of Middleport, Schuylkill County, Pa. Methyl salicylate may also be artificially prepared by heating a mixture of methyl alcohol, sulphuric acid and salicylic acid whereby at first methyl-sulphuric acid is formed which is then converted into methyl ether and sulphuric acid:-- {OH {OCH_{3} SO_{2}{ + CH_{3}OH = SO_{2}{ + H_{2}O {OH {OH {OCH_{3} {OH SO_{2}{ + C_{6}H_{4}{ = {OH {COOH {OH {OH C_{6}H_{4}{ + SO_{2}{ {CO.OCH_{3} {OH. Etherification succeeds without difficulty, it being sufficient to heat the mixture for some time and then pour it into water whereby the ether separates as a heavy layer of oil. After washing with water distil in a direct current of steam. The ether thus obtained is as clear as water and, as regards its other properties, does not differ from the naturally occurring oil. This artificial wintergreen oil is now much used for perfuming purposes. Wintergreen oil is said to be frequently adulterated with sassafras oil which is also specifically heavier than water. If, according to Hayer, 5 drops of the oil in a test-tube be mixed with 10 drops of crude concentrated nitric acid, a deep blood-red fluid results in one minute if oil of sassafras is present. In the course of another minute, the fluid separates a brown resinous mass. Pure oil, on the other hand, is but little altered.