HOT SPRINGS. 



ground we see effusions : of watery vapour and 

 of gaseous carbonic acid, mostly free from all 

 admixture of azote(^®*) ; of carburetted hydro- 

 gen gas (in the Chinese province of Sse-Tschu- 

 an(^^^) for thousands of years, and in the State 

 of New York, where, in the village of Fredonia, 

 it has lately been employed for economical pur- 

 poses in heating and lighting ; of sulphuretted 

 hydrogen gas ; of sulphur fumes, and more 

 rarely of sulphurous and hydrochloric acid va- 

 pours("«). Such emanations from fissures in 

 the ground do not only indicate the dominion 

 of volcanoes long extinct or still burning ; they 

 are farther observed exceptionally in districts 

 in which neither trachyte nor any other volcanic 

 rock meets the eye exposed upon the surface. 

 In the Andes of Quindiu I have seen sulphur 

 precipitated from hot sulphureous vapours issu- 

 ing out of mica slate, at a height of 6410 feet 

 above the level of the sea('^^) ; whilst the same, 

 and, as it used to be regarded, primitive rock, 

 in the Cerra Cuelo, near Ticsan, south of Quito, 

 exhibits an enormous bed of sulphur in pure 

 quartz. 



Of all the air-springs which the earth pours 

 forth, those of carbonic acid gas are still at the 

 present time the most important both in num- 

 ber and extent. Germany, in her deeply-cut 

 valleys of the Eifel, in the neighbourhood of 

 Lake Lach, in the Kesselthal of Wehr, and in 

 Western Bohemia, as also in the burning hearths 

 of the primeval world, or their vicinity, shews 

 us these effusions of carbonic acid as a kind 

 of last effort of volcanic activity. In former 

 epochs, where, with a higher temperature of 

 the earth, and the frequency of fissures yet un- 

 filled, the processes which we are here descri- 

 bing proceeded more actively, where carbonic 

 acid gas and watery vapours were mingled with 

 the atmosphere in larger quantities than at 

 present, the youthful vegetable world, as Adolph 

 Brongniart("8) has acutely observed, must have 

 attained almost everywhere, and independently 

 of geographical position, to the most rank lux- 

 uriance and evolution of its organs. In the 

 ever hot, ever moist atmosphere, surcharged 

 with carbonic acid, vegetables must have found 

 such vital excitement, such superfluity of nour- 

 ishment, as enabled them to supply the material 

 of those beds of coal and lignite, the exhaustion 

 of which it is difficult to conceive, and which 

 now serve as foundations for the physical 

 strength and the welfare of nations. Such beds 

 are principally contained in basins, and are pe- 

 culiar to certain parts of Europe. They are 

 abundant in the British Isles, in Belgium, in 

 France, on the Nether Rhine, and in Upper 

 Silesia. In the same primeval times of all- 

 pervading volcanic action, too, must those enor- 

 mous quantities of carbonaceous matter have 

 issued from the bowels of the earth which all 

 the limestone rocks contain, and which, separ- 

 ated from oxygen, and represented in the solid 

 form, composes about an eighth part of the ab- 

 solute bulk of these great mountain masses 

 ("'). The carbonic acid which the atmosphere 

 still contained, and which was not absorbed by 

 the alkaline earths, was gradually consumed 

 by the vegetation of the primeval world, so that 

 the atmosphere, purified by the processes of 

 vegetable life, by and by contained no more of 

 the gas than was uninjurious to the organiza- 



tion of such animals as people the earth at the 

 present time. Sulphurous or sulphuric acid 

 vapours, too, occurring more frequently and 

 much more abundantly then than now, occa- 

 sioned the destruction of the inhabitants of the 

 inland waters — mollusca and numerous genera 

 of fishes, as well as the formation of the strange- 

 ly-twisted beds of gypsum which have often 

 apparently been shaken by earthquakes. 



Under precisely similar physical relations 

 there were further thrown out from the bosom 

 of the ground various gases and liquids, mud, 

 and, from the eruption-cones of volcanoes, 

 which are but a species of intermitting springs, 

 streams of molten earths(^'''). All these mat- 

 ters owe their temperature and the nature of 

 their chemical constitution to the place of their 

 origin. The mean temperature of ordinary 

 springs is lower than that of the atmosphere 

 of the place where they appear, when the wa- 

 ter is derived from high levels ; their tempera- 

 ture increases with the depth of the strata with 

 which they come in contact at their origin. 

 The numerical law of this increase has been 

 stated above. The mixture of the waters which 

 come from the mountain elevations and from 

 the depths of the earth, renders the position of 

 the isogeothermal linesC^'*), or hues of like in- 

 ternal heat of the earth, difficult of determina- 

 tion, when the conclusion has to be come to 

 from the temperature of springs as they rise. 

 So, at least, did I and my friends find it in some 

 experiments which we made in Northern Asia. 

 The temperature of springs, which has been so 

 constant an object of physical investigation for 

 the last half century, depends, like the height of 

 the line of perpetual snow, on numerous and 

 highly complex causes. It is a function of the 

 temperature of the stratum in which they have 

 their origin, of the capacity for heat of the ground, 

 and of the quantity and temperature of the at- 

 mospheric or meteoric water that falls(*"), 

 which last, again, according to the mode of its 

 origin, differs in its temperature from that of 

 the lower strata of the atmosphere(^"). 



Gold springs, as they are called, can only give 

 the mean temperature of the air if unmixed 

 with water that is rising from great depths, or 

 that is descending from considerable heights, 

 and when they have flowed for a very long way 

 under the surface of the earth — in our latitudes 

 from 40 to 60 feet, in the equinoctial zone, ac- 

 cording to Boussingault, one foot(^^*). These 

 depths are those, in fact, of the stratum of earth 

 in which, in the temperate and torrid zone re- 

 spectively, the point of invariable temperature 

 begins, in which the hourly, diurnal, or month- 

 ly variations in temperature of the air are no 

 longer perceived. 



Hot springs burst out of the most diversified 

 mineral strata ; the hottest of all the perma- 

 nent spnngs which have yet been observed, 

 and which I myself discovered, flow remote 

 from all volcanoes. I here refer to the Aguas 

 calientes de las Trincheras, between Puerto 

 Cabello and New Valencia, and to the Aguas 

 de Gomangillas, near Guanaxuato in Mexico, 

 The first spring, issuing from granite, indicated 

 90-3° C. ; the second, which breaks from basalt, 

 shewed 96-4° C. The depth of the source of 

 water of these temperatures, from what we 

 know of the law of increase of temperature in 



