900

Appendix.

Ill

soon falls, and the water loses its taste. If the iron be in the state of sulphate,however, no sediment falls ; and the black colour is produced by the above test,even after the water has been boiled and iiltered. There are many chalybeates inGreat Britain ; but the most celebrated are Tunbridge, Brighton, and Peterhead :the Cheltenham spring also contains carbonate of" iron ; but on account of thelarge proportion of saline matter, and its strong purgative properties, it is notranked in this class. The Spa springs also belong to this class.

Chalybeate waters are powerful tonics, and are employed in dyspepsia, scrophu-lous affections, cancer, amenorrhcea, chlorosis, and the other diseases of debilityfor which the artificial preparations of iron are used. Much of the benefit derivedfromtheuse of chalybeate waters depends on the extreme division of the metallic saltsthey contain, as well as the vehicle in which it is held in solution ; while at thesame time their operation is much modified by the carbonic acid by which the ironis suspended. When the water is a carbonated chalybeate, it should be drank themoment it is drawn from the spring : but the same precaution is not necessarywith a water containing sulphate of iron.

3. Sulphureous waters derive their character chiefly from sulphureted hydro-gen gas ; which in some of them is uncombined, while in others it is united withlime or an alkali. They are transparent •when newly drawn from the spring, andhave the foetid odour of rotten eggs, which is gradually lost from exposure to theair, and the water becomes turbid. When they are strongly impregnated withthe gas, they redden infusion of litmus, and exhibit some other of the characteris-tics of acids; and even in a weak state blacken silver and lead. Besides contain-ing sulphureted hydrogen gas, they are not unfrequently, also, impregnated withcarbonic acid. They generally contain muriate of magnesia or other saline mat-ters, which modify their powers as a remedy.

The most important sulphureous springs in this island are those of Kilburn,Harrowgate, and Moffat; on the continent, Aix la-Chapelle and Barege; whichare resorted to chiefly for the cure of cutaneous eruptions, and are applied locallyas well as drunk. They are slightly sudorific and diuretic, and are apt to occa-sion in some patients head-ach of short duration, directly after they are drunk.They are also employed for curing visceral and scrophulous obstructions, torporOf the intestines, and some dyspeptic and hypochondriac cases.

4. Saline mineral waters owe their properties altogether to saline compounds.Those which predominate, and gv>je tte\x characters to the waters of this class, areeither,

1. Salts, the basis of which is lime ;

2. Muriates of soda and magnesia;

3. Sulphate of magnesia;

4. Alkaline carbonates; particularly carbonate of soda.

They are mostly purgative, the powers of the salts they contain being verymuch increased by the large proportion of water in which they are exhibited. Themost celebrated saline springs are those of Cheltenham and Leamington, in Eng-land ; Pitcaithly, in Scotland; and Sedlitz, on the continent. They are employ-ed in diseases which require continued and moderate intestinal evacuations - suchas dyspepsia, hypochondriasis, chronic hepatitis, jaundice, and strumous swellings.They are more grateful to the stomach when carbonic acid also is present ■ andwhen they contain iron, as in the case of the Cheltenham spring, their tonic powers,combined with their purgative qualities, render them still more useful in dyspepticcomplaints and amenorrhcea.

To this class the water of the ocean belongs. The quantity of saline matter seawater contains varies in different latitudes : thus between 10 D and 20 J it is rathermore than J^th ; at the equator it is A-th ; and at 57° north it is only -'-th. Thesaline ingredients in 10,000 parts of sea water, according to the last analysis ofDr. Murray >, are, muriate of soda, 220-01 ; muriate of lime, 7-84; muriate ofmagnesia, 42-08; and sulphate of soda, 33-16. When brought up from a greatdepth, its taste is purely saline ; but when taken from the surface it is disagreeablybitter, owing, perhaps, to the animal and vegetable matters suspended in it. Itsspecific gravity varies from 1'0269 to 1 -0285 ; and it does not freeze until coofed

1 Edinburgh Transactions, vol. viii. p. 205. The water was taken from th eFrith of Forth, and was of the. specific gravity I -029.