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The London Dispensatory, containing : 1. the Elements of Pharmacy ; 2. the botanical Description, natural History, chemical Analysis, and medicinal Properties of the Substances of the Materia Medica ; 3. the pharmaceutical Preparations and Compositions of the Pharmacopoeias of the London, Edinburgh, and Dublin Colleges of Physicians ; the Whole forming a Practical Synopsis of Materia Medica, Pharmacy, and Therepeutics
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part i. Elements of Pharmacy. Ixxvii

water, if a quantity of water fully impregnated with any gas,as carbonic acid, for example, be exposed to the atmosphere,or any other gaseous body, the greater part of the absorbedgas escapes from the water and mixes with the superincumbentair; and, therefore, to preserve the impregnation complete, theaerated water must be preserved in well-stopped bottles; orunder an atmosphere of the same gas it contains.

Such are the principal circumstances connected with theabsorption of the less absorbable gases: those which are moreabsorbable appear to belong to the class of acids and alkalies.

Table of the very absorbable gases hitherto examined, placedin the inverse order of their absorbability, with the numbers ofmeasures of each absorbed by one measure of pure water.*

Na?nes qf gases. Measures absorbed.

Oxymuriatic acid gas (chlorine) - - - 2Cyanogen ---------- 41

Sulphurous acid -------- 43-78

Fluosilic aeid........363 +

Muriatic acid -- ------516

Fluoboric acid -------- 700

Ammoniacal --------- 780

The water when saturated with these gases undergoes an in-crease of bulk. The following table exhibits this change, sup-posing the original bulk to have been l. 1

Saturated with Cubic inches.

Oxymuriatic acid gas (chlorine) - - 1 -002 +Sulphurous acid ------- 1-040

Fluosilic acid -------- ------

Muriatic acid -------- 1-500

Ammoniacal -------- 1-666

The absorption of these gases is the consequence of theexertion of an affinity between them and water; but in everyrespect the circumstances attending it are exactly the same asthose attending the absorption of the former class of gases;except that " most of the gases belonging to the first classexperience an expansion when absorbed; while all those ofthe second undergo a condensation, their affinity for waterbeing greater than their elasticity."

With regard to the absorption of gases by other liquids,scarcely any very decisive experiments have been made.

3. OF THE COMBINATION OF GASES WITH SOLIDS.

From the difference which exists between the constitutions ofgases and solids, their combination appears to be opposed by

' Thomson's Chemiitry, 5th edit. iii. 68. * Ibid, 68.

 
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