CHEMICAL ANALYSIS,

AND MEDICAL

PROPERTIES OF THE HOT BATHS AND COLD SPRINGS IN THE VALLEY OF THE FURNAS; WITH OBSERVATIONS ON THE DISEASES FOR THE REMEDY OF WHICH THEY ARE SUITABLE.

The springs used for medicinal purposes or for luxury are the following:

HOT SPRINGS USED FOR BATHS.

1. The great

water.

66

Caldeira;" a boiling alkaline

2. The "Quentúras;" a hot carbonated chalybeate water.

3. The "Mistúras;" a mixture of hot alkaline water and cold carbonated chalybeate water.

COLD SPRING.

4. "Ágoa azêda;" a highly carbonated chalybeate water. This is usually drunk, but it may be employed as a cold bath.

346

CHEMICAL ANALYSIS.

TEPID SPRING.

5. “Ágoa de férro;" a tepid carbonated chalybeate, containing more iron and less carbonic acid than No. 4. Never used as a bath, the quantity being small.

I am indebted for the account of the chemical analysis of these waters to the kindness of Sir James Clark, Bart., to whom (knowing the interest which he takes in the subject of mineral waters) I forwarded the specimens which I brought from St. Michael's. The analysis was made by Professor Graham of University College, London.

1. THE GREAT CALDEIRA.

The " Caldeira," or caldron, is a circular pool about ten feet in diameter, in the centre of which the water boils up to the height of three or four feet among fragments of rock. The steam, which escapes in large quantities, smells slightly of sulphuretted hydrogen (like a hard boiled egg). The water is opaline, and very soft to the skin when cooled. Its temperature is about the boiling point. It deposits silex copiously in the channels through which it flows,

CHEMICAL ANALYSIS.

347

and pieces of fern, moss, sticks, &c., which are covered with the water for any length of time, become petrified. The soil around the Caldeira has become whiter than pipe-clay from the constant action of internal heat and of sulphurous vapours on the pumice or on the volcanic clay. In some places, the iron or sulphur which abounds in the soil tinges it with orange colour, red, and green. Fine crystals of sulphur, as well as silky crystals of alum, are very abundant in the earth surrounding this Caldeira, and in its immediate neighbourhood.

ANALYSIS.

An imperial pint of the water from the great Caldeira contains:

Chloride of sodium, with small quan

tities of an alkaline sulphate, sul

phuret, and carbonate

Grs.

11.83

2.60

14.43

"This water," says Professor Graham, "differs from all the others in containing little gaseous matter. It is also remarkable for the absence of all the earthy bases. To this last circumstance, and the presence of a portion of silicate and carbo

348

CHEMICAL ANALYSIS.

nate of soda, it is indebted for its agreeable softness to the skin. It is, indeed, distinctly alkaline to test paper. A minute quantity of sulphur is present in the form of sulphuret of sodium."

This analysis, coming as it does from one of the highest authorities, is, of course, a correct one of the specimen which was examined. But I suspect that, owing either to the cork of the bottle, or to the wax with which it was covered being imperfect, there might have been some escape of gas. Professor Dunn, of Dartmouth College, in America, (see Dr. Webster's Description of the Island of St. Michael's,) found, in a pint of the water which he examined, 26.4 cubic inches of carbonic acid gas, with a trace of sulphuretted hydrogen; and Dr. Turner also found carbonic acid in all the specimens of the water brought from this spot which he analysed.*

*Alkaline waters are such as contain a free and carbonated alkali, and, consequently, either in their natural state, or when concentrated by evaporation, possess an alkaline reaction. These springs are rare. The best instance I have met with is in water collected at the Furnas, St. Michael's, Azores, and sent to the Royal Society of Edinburgh by Lord Napier. These springs contain carbonate of soda and carbonic acid, and are almost entirely free from earthy substances.

CHEMICAL ANALYSIS.

349

This agreed also with my impression from bathing in the water. The springs in the immediate neighbourhood are all highly charged with carbonic acid gas, and the stimulating effect of the water of the great Caldeira upon the skin is so similar to that of water charged with carbonic acid gas, that it is difficult not to believe, whilst using it, that the gas also exists in it, but in smaller quantities than in the other springs. The natives call it a sulphurous water, and from the steam smelling of sulphuretted hydrogen, and from the existence of crystals of sulphur in the crevices of the soil through which the steam rises in the immediate proximity of the boiling spring, there seems more reason for believing in the correctness of the term than the chemical analysis

warrants.

The quantity of silex held in solution by the water of this caldeira is considerably greater than that found in any of the thermal springs of Germany, but is less than in the Geysers of Iceland. The large quantity is owing to the very high

Of five different kinds of these waters which I examined, the greater part also contained protoxide of iron, hydro-sulphuric acid, and chloride of sodium."-Turner's Elements of Chemistry, 5th edit. 1834, p. 1028.