358 A. Vaughan Jennings — Geology of Bad Nauheim. 



Sucb is a brief summary of the history and nature of the Nauheiui 

 borings. From the geologist's point of view the features of interest 

 fall into two series : first, the strata traversed by the borings ; and 

 second, the temperature and contents of the waters themselves. 



The former question may be more conveniently dealt with in the 

 concluding section of this paper, but it may be noted, in passing, 

 that those borings which are likely to give most help in explaining 

 the subterranean structure are Nos. 1-7, 11, and 12. An almost 

 straight line can be drawn through these, approximately at right 

 angles to the general strike of the rocks. 



The results of chemical analysis of the contents of the different 

 springs are given in many of the books of local and medical 

 information published on the spot, and there is no necessity to 

 investigate the numerous variations here. With a view to geological 

 considerations, however, it may be well to reproduce the details of 

 one typical analysis, that of the Friedrich-Wilhelm's Quelle (No. 12). 



Amount per 1,000 Grammes of Water. ^ 



Sodium chloride ... 29-29 



Lithium diloride .. . ... ... ... ... -05 



Potassium chloride ... ... ... ... I'll 



Ammouium chloride -07 



Calcium chloride .. . ... ... ... ... 2'32 



Magnesium chloride ... ... ... ... -52 



Calcium sulphate .. . ... ... ... ... -03 



Strontium sulphate ... ... ... ... "04 



Calcium carbonate ... ... ... ... 2'60 



Iron carbonate '04 



Silica ... -02 



At the risk of seeming to break the promise given above to keep 

 entirely to such matters of detailed description as bear on the 

 geology of the district, I am tempted to insert here a note on the 

 process by which the concentrated brine, and subsequently the dry 

 salts, are obtained. It is distinctly difficult at first for the enquiring 

 visitor to understand the meaning of the curious structures round 

 the town ; and the process is not only interesting from the com- 

 mercial, chemical, and mechanical points of view, but in some of 

 its features is very suggestive to the biologist and geologist as well. 



About the middle of the century the old method of simple 

 evaporation in troughs was discarded and a more elaborate system 

 adopted. A short distance south of the town a number of long tanks 

 across the plain of the Usa were constructed, and above each an 

 immense erection of heavy timber frameworks. The interspaces of 

 these massive structures are entirely filled in with what may in 

 general be termed ' brushwood,' but which consists almost entirely 

 of close-packed bushes of blackthorn. Along the top of each of 

 these 'gradirwerke,' as they are termed, runs a trough containing 

 the water from the springs with nearly all its lime, iron, and salts ; 

 and this is allowed to percolate down through the brushwood 



i_ These are the chief constituents of the dissolved solids. There are traces of 

 various other substances, but those given here are such as can be recorded in the 

 second decimal place. 



