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place in his lungs (Beddoes , New Method of treating Pulmonary Consump-tion. i p- 44). If we speak while the chest is tilled with hydrogen, aremarkable alteration is perceived in the tone of the voice, which becomessofter, shriller, and even squeaking. That this effect is, in part at least,if not wholly, physical, is shewn by the fact that wind instruments (asthe flute, pitchpipe, and organ) have their tones altered when playedwith this gas. The conclusion which has been drawn by several expe-rimenters as to the effects of breathing hydrogen is, that this gaspossesses no positively injurious properties, but acts merely by excludingoxygen.
Uses. — (a). In pulmonary consumption Dr. Beddoes recommended in-halations of a mixture of atmospheric air and hydrogen gas, on theground that in this disease the system was hyperoxygenised. The in-halation was continued for about fifteen minutes, and repeated severaltimes in the day ( New Method of treating Pulmonary Consumption ).Ingenliousz fancied that it had a soothing effect when applied to woundsand ulcers.
(b.) In rheumatism and paralysis it has been used by Reuss as aresolvent.
(c.) A flame of hydrogen has been employed in Italy as a cautery, tostop caries of the teeth {Diet. Mat. Med. par Merat et Re Lens).
{d.) Hydrogen water (an aqueous solution, prepared by artificial pres-sure) has been employed in diabetes {ibid}.
Aqua. — Water.
History. —The ancients regarded water as an elementary substance,and as a constituent of most other bodies. This opinion, apparentlysupported by numerous facts, was held until the middle of the last cen-tury, when the lion. Mr. Cavendish proved that this liquid was a com-pound of oxygen and hydrogen. It is, however, only doing justice toMr .Watt to say, that he had previously inferred this to be the compositionof water, but was deterred from publishing his opinion in consequence ofsome of Dr. Priestley’s experiments being apparently opposed to it.
Natural History . — {a.) In the inorganized kingdom. Water existsin the atmosphere; forms seas, lakes, and rivers; it is mechanically disse-minated among rocks; and, lastly, it constitutes an essential part of someminerals.— In the atmosphere it is found in two states: as a vapour(which makes about one-seventieth by volume, or one one-hundredth byweight, of the atmosphere) it is supposed to be the cause of the bluecolour to the sky; and, in a vesicular form, it constitutes the clouds.Terrestrial water forms about three-fourths of the surface of the terra-queous globe. The average depth of the ocean is calculated at betweentwo or three miles. Now, as the height of dry land above the surface ofthe sea is less than two miles, it is evident, that if the present dry landwere distributed over the bottom of the ocean, the surface of the globewould present a mass of waters a mile in depth. On the suppositionthat the mean depth of the sea is not greater than the fourth part of amile, the solid contents of the ocean would be 32,058,939! cubic miles(Thomson’s System of Chemistry , 6th ed. vol. iii. p. 195). The quantityof water disseminated through rocks must be, in the aggregate, veryconsiderable, although it is impossible to form any correct estimate of it.