260 Mr. H. M. Witt's Chemical Examination of certain 



Travertin Springs. 



"From the plain of Selraas northwards," says Mr. Loftus, 

 " calcareous tufa-springs are of continual occurrence, and those 

 of Derik are good examples of them. 



" The springs are close to the village of Derik. The water rises 

 with great force in the more northerly basin at regular intervals ; 

 but in the other irregularly, at intervals of five or seven seconds, 

 gurgling from below, and throwing up a strong jet to the height 

 of a foot above the surface. The temperature of the two springs 

 is the same, viz. 96° F., indicating a common origin. As the 

 surface of the water cools, numerous thin lamellse of cream- 

 coloured carbonate of lime are formed, and float about like scum. 

 These lamellae are sometimes 2 inches long, and about the thick- 

 ness of a wafer. As the water flows onwards, cooling in its 

 passage, it deposits the calcareous granules of carbonate of lime 

 which become cemented together, and at length are sufficiently 

 compact to be called travertin. These hot springs of Derik are 

 much resorted to for every species of complaint to which the 

 Kourd is subject." The three samples of these springs collected 

 were the following. 



No. 1. Large Saline Spring, Derik near Selmas. 



It was collected August 18, 1852, the spring at the time 

 having the temperature, as before mentioned, of 96° F. 



This water possessed no odour of sulphuretted hydrogen, and 

 did not contain nearly so much free carbonic acid as the prece- 

 ding ; but it had floating about in it granular particles of car- 

 bonate of lime, although after filtration it retained in solution 

 only a comparatively small quantity of lime ; and this might be 

 expected ; for being a hot spring, it would contain but little free 

 carbonic acid in solution after exposure for a short time to the 

 air, and therefore the greater part of the lime which existed in 

 solution in the form of bicarbonate at the moment of emergence 

 from its subterranean source, would be speedily deposited by the 

 evaporation of the carbonic acid which held it in solution in the 

 foi-m of the travertin and granular carbonate of lime described 

 by Mr. Loftus. 



Its specific gravity was 1-0013, and the quantity of solid 

 matter left on evaporation amounted to 110'027 grains in the 

 gallon, showing it to be a far less saturated water than the two 

 before described. 



In composition this saline matter differed from either of the 

 preceding, in that it contained but a very small quantity of 

 chlorides, consisting chiefly of alkaline carbonates, with about 

 14 grains of carbonate of lime, and a minute proportion of oxide 

 of iron, alumina, and silica. 



