1824.] Mineral Waters of Carlsbad. 125 



succession of air bubbles rising to the surface of the water. The 

 openings made in the course of this examination were built over 

 with mason work, every joint of which became speedily stopped 

 up with the carbonate of lime deposited by the water. It still 

 continues to retain the water completely, and to constrain it to 

 flow through the pipes, which have been placed in the reservoir. 

 These pipes also become by degrees incrusted with the sprudel- 

 stone, and must be cleared four times every year to prevent their 

 being clogged up altogether. 



What is called the Sprudel is merely an opening in the reser- 

 voir, from which, however, the water rises only at intervals, in 

 such a manner that air and water are discharged from it alter- 

 nately. This remarkable phenomenon is occasioned by the car- 

 bonic acid gas, which gradually accumulates in the upper vault 

 of the reservoir, and which, owing to the diminished pressure, 

 the water is constantly emitting, in proportion as it recedes from 

 the interior of the earth. This gas, having no means of exit, of 

 necessity reacts upon and presses down the expanse below, until 

 it at last escapes through the canal which, until then, had fur- 

 nished a passage for the water. Hence air and water are dis- 

 charged through the opening successively, in proportion as the 

 elasticity of the gas accumulates and is expended.* This alter- 

 nation takes place at the Sprudel 18 or 19 times every minute. 

 There are many other openings in the immediate neighbourhood, 

 from which the water is discharged even in greater abundance ; 

 but it proceeds from them all in an uninterrupted stream. 



The quantity of hot water which flows from these springs is 

 altogether astonishing. Many attempts have been made to es- 

 timate it ; but all of these are of so indirect a nature, that they 

 do not deserve to be regarded as even approximations to 

 accuracy .+ 



Analysis of the Water. 



The water employed for this analysis was taken from the 

 Sprudel, and was preserved in bottles furnished with ground 

 glass stoppers, in order to prevent the diminution in the quan- 

 tity of oxide of iron, which is always occasioned by a common 

 cork. The Carlsbad water is clear and colourless. Whennewlv 

 drawn its taste resembles that of weak chicken broth, but after 

 some hours it becomes unpleasantly alkaline. It has no peculiar 

 smell, nor can any reagent detect in it the minutest trace of sul- 



• An ingenious illustration of a similar natural intermitting spring will be found 

 towards the conclusion of the introductory portion of the article Steam Engine, by Prof. 

 Kobison, in the Encyclopaedia Britannica; or in his System of Mechanical Philosophy, 

 edited by Dr. Brewster, vol. ii. p. 43. 



+ Klaproth's estimation of this quantity is certainly twenty times too high. From a 

 measurement made on the spot, Nov. I, 1811, it was calculated that the Sprudel and 

 the Hygeian spring alone discharge 19'2'j millions of German cubic feet of water every 

 24 hours. 



