= 4] A IR the reception of fresh air. All per- sons, but es] ;cially children, ought to resort, at least for a short time, foyto this method of enjoying the salubrious influence of that uni- v al agent. To persons of a robust and vi- gorous habit, we cannot recommend a more bracing and pleasant reme- dy. In this place, however, we shall give only an historical sketch simple air-bath, without ex- patiating on its nature and el Its benefits were fir^t pointed out by the la'e illustrious Franklin-, who describes it with his peculiar simplicity, in the following words : " Every morning at day-break I get out of bed, and pass half anhour, tjv an hour, in my chamber, accord- ing to the season, in writing or without any clothes; and this seems rather pleasant than
- and if I return to bed,
as is sometimes the case, before I dress myself, I have an addition to my night's rest of one or two hours . sweeter than you can ima- gine." The late Lord Monbobdo, a man of an amiable, though eccentric cha- ir, was so decided an adv For the air-bath, that he accustomed himself to take violent ex< when quite undressed, in the open air. In this practice he persevered till within a few years of his (which happened in May, 1 799) j he also anointed his body, like die ancients, with aromatic oils, espe- cially in a moist and heavy atmos- phere. — Whether by these singular expedients, or by a frugal and phi- losophic mode of life, he ei extraordinary degre e of mental sei nity ai I bodilj en rg . which prolonged his existence to th< r ot age, we shall not pretend to decide. AIR AIR-JACKET, a dress made of leather, in which are contained se- veral bags or bladders, composed of the same materials, and communi- cating with each other. These are filled with air blown through a lea- ther tube, having a brass stop-cock, accurately ground at its extremity. In order to confine this elastic fluid, the jacket must previously be wet- ted; and thus the person is sup- ported in the water without any ef- fort, by the aid of diese bladders placed near die breast. Those who are proficients in the art of swim- ming, condemn such artificial as* sistance as cannot always be readily •.n?d : in our opinion, the most I method of acquir- es useful talent, is that n tioned by Dr. Struve, in his Ger- man 'treatise on the Physical Educa- tion of Children, lately published, with three Introductory Lectures 1 y the Editor of this Encyclop — See the article Swimming. Aix-la-Qkapellt. See Minerax Waters. ALABASTER, is a species of stone, the basis of which is calcare- ous earth. Mixed with any acid, no effervescence takes place , ia this respect it differs from marble, but in its chemical properties it re- sembles gypsum, selenite, and ter of Paris. There are diree s] of alabaster : the white-shining ; the yellowish : and the variegated, a mixture of yellow and red. The last d, violently ferments with aqua-fortis, and burns to a pale yellow. It was formerly brought from Egypt, but is now obtained in several pans of England. Mr. Boyle, speaking of the first sort, says, that, if fine!) powdered, and set in a bason over the fire, it will, v. hen hot, assume the appear- ance of a fluid, rolling in waves, yield-
