104

ELEMENTS OF MATERIA MEDICA.

which they were supposed to communicate to the system. These notionsare now exploded.

In asphyxia arising from a deficiency of atmospheric air, or frombreathing noxious vapours, the inhalation of oxygen gas has been said tobe, and probably is, useful. On the same principle, it may be employedduring an attack of spasmodic asthma, when there is danger of suffoca-tion, but it is at best only a palliative, and has no power of preventingthe occurrence of other attacks. Chaussier has recommended its use inchildren apparently still-bom. To combat the asphyxia of malignantcholera, inhalations of oxygen were tried in Russia, Poland , Prussia, andFrance, but without success (Herat and De Lens, Diet . Mat. Med. tom. 5 rae .p. 143).

A'qua Oxyge'nii .— Ox ygen Water.

At the mean pressure and temperature of the atmosphere, 100 vols. ofwater dissolve, according to Dalton and Henry ( Elem. Experim. Chem.)3'7 vols. of oxygen gas, according to Saussure {ibid.) 6‘5 vols. By pres-sure in a proper machine, water may be charged with a much largerquantity (Jourdan, in the Pharmacopee Universelle, says with half its\ olunie) of gas. This solution has been termed oxygenated water, but isa very different substance to the peroxide of hydrogen, which also hasbeen known by this appellation. It has been used to the extent of oneor two bottlefuls daily, as a slight excitant. It is said to increase theappetite and promote the secretions; and to be serviceable in spasm ofthe stomach, amenorrhcea, hysteria, atonic dropsy, &c.

Order II.— Chlorine and its Aqueoos Solution.

Chlorin'ium. — Ohio'vine.

History, synonymf.s, and etymology.— This gas was discovered byScheele in 1774, who termed it dephlogisticated muriatic acid. Berthollet ,in 1785, named it oxygenated muriatic acid. Sir II. Davy called itchlorine (from green), on account of its colour.

Natural History . —It is found in both kingdoms of nature, (a.) Inthe inorganized kingdom it exists principally in combination with sodium,either dissolved in the water of the ocean or forming deposits of rock salt.Chlorine also occurs native, in combination with magnesium, calcium,lead, silver, &c. Free hydrochloric acid is met with in the neighbour-hood of volcanoes, and is probably produced by the decomposition ofsome chloride. ( b .) In the organized kingdom, it is found in combination,in both animals and vegetables. Sprengel ( Decand. Physiol. Veg. tom. i.p. 220), says maritime plants exhale chlorine, principally during thenight. Hydrochloric acid, in the free state, exists, according to Dr. Front,in the stomach of animals during the process of digestion.

Preparation. —There are several methods of procuring chlorine gas

1. By adding sulphuric acid to a mixture of common salt and binoxideof manganese .—This is the cheapest and most usual method of preparingit. Mix intimately three parts of dried common salt with one partof the binoxide of manganese, and introduce the mixture into a retort.Then add as much sulphuric acid, previously mixed with its own weightof water, as will form a mixture of the consistence of cream. On the