138] ATH Athamanta LiVanon, L. See Mountain Spignel. Athletic Art. See Gymnastic Exercise. ATHLETIC Habit, a term which implies a strong constitution of body. Among the ancients, it signified a robust and corpulent state, such as the athletes endea- voured to acquire. The athletic habit is considered as the highest point of health ; yet such a state is equally precarious, and exposed to danger; for when the body is no longer capable of improvement, the next change must be for the reverse : hence " its most healthy condition closely borders on disease ; and the seeds of distemper are planted in the very fulness or luxuriance of our fluids." . ATMOSPHERE., a term derived from the Greek words vapour and sphere, whence ithas been generally applied, to signify that surrounding mass of air which consists of aque- ous and other vapours, the electric and magnetic fluids, &c. but the altitude or extent of which has never been accurately ascertained. . Under the article Air, p. 21, we have already mentioned the general properties of this surround- ing medium ; hence we shall here observe, by way of supplement, that according to the discoveries of modern chemists, though still op- posed by Dr. Priestley, the at- mosphere is not a simple, but a compound body. Pure air, or tKxygen, is but a small part of its composition, while that of azote, or mephitic air, constitutes about three-fourths. The former is, on account of its more salutary pro- perties, better adapted to the re- spiration of men and animals, than common atmospheric air ; and though, by its powerful influence, ATM it is eminently calculated to restore the life of creatures, when anima- tion is accidentally suspended, so that the late Dr. Ingenhouz has justly termed it vital air ; yet it is net proper for long-continued re- spiration. Azote, or suffocative air, on the contrary, is unfit for sup- porting animal life, as it is abso- lutely irrespirable. Hence it must be obvious, that a greater or less proportion of this noxious ingre- dient in our atmosphere, arises from the innumerable processes of combustion, putrefaction, and re- spiration, whether by nature or art, in all large and populous ci- ties. For this reason, country-air is so much preferable, that certain invalids, especially pthisical and asthmatic persons, are obliged to retire from towns to a purer, or, at least, less vitiated region. Hence also, it will be understood, that sea-air must be infinitely more conducive to support the most im- port :mt process of life ; as, by the constant agitation or commotion of the watery element, mephitic va- pours are in a manner neutralized; though the azote enters into no combination with that fluid : upon a similar principle, it has been sug- gested (p. 23) to purify the foul air of pits and wells, before any person attempts to descend into them, by simply pouring in a few pailfuis of water, whether boiling or cold. By the same method also, the noxious vapours of old wine- casks, and other vessels or recep- tacles of corrupted air, may be effectually deprived of their perni- cious, and often fatal, influence. The third constituent part of the common atmosphere, viz. fixed air, or car home acid gas, naturally exists in so small a proportion, as to form only a hundredth part of the whole, and