376 Royal Society : — 



a remarkable phsenomenon to be brought to ligbt), far from 

 being a reproach to the method employed, is to be regarded as 

 a quality inherent in the subject matter under representation, 

 and inexpugnable, as such, in the very nature of things. 



K Woolwich Commorij 

 October 2, 1858. 



XLIII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 312.] 



March 18, 1858. — The Lord Wrottesley, President, iu the Chair. 



THE followiug communications were read : — 

 " On the probable Origin of some Magnesian Rocks." By 

 T. Sterry Hunt, Esq., of the Geological Survey of Canada. 



The deposits of mineral matters from natural waters offer many 

 points of interest to the geologist. Besides the rock-salt and gypsum, 

 w'liich in many cases have doubtless been formed by the spontaneous 

 evaporation of saline waters, it is well known that many mineral 

 springs charged Avith carbonic acid under pressure, deposit great 

 quantities of earthy salts when they come to the surface, and that 

 the travertines thus formed often constitute extensive masses. The 

 deposit from the hot alkaline saline springs of Carlsbad, which forms 

 great beds, wasfound byBerzelius to consist chiefly of carl)Ouate of lime, 

 Avith portions of oxide or carbonate of iron, and small quantities of 

 silica, strontia, phosphoric acid and fluorine ; the analyses of other 

 chemists have added to the list of elements met with in these and 

 similar precipitates, manganese, zinc, cobalt, nickel, chromium, arsenic, 

 autimony, tin, copper and lead. Carbonate of magnesia is however 

 wanting, or present only in very small proportion, in these deposits ; 

 and the same is true of the calcareous sinter from cold springs. The 

 Carlsbad water, however, contains for 1 7 parts of carbonate of lime 

 ] parts of carbonate of magnesia ; but this latter salt, according to 

 Berzelius, is only deposited after evaporation. 



The analyses by Berzelius and Struve of the various carbonated 

 waters of Germany, show tbat carbonate of lime is generally present 

 in much larger quantities than carbonate of magnesia ; and it is only 

 in the waters of Piillna and the Elisenbrunnen of Kreuznach, which 

 contain very little carbonic acid, tbat we find a large amount of 

 carbonate of magnesia, with a small portion of carbonate of lime. 

 The water of Piillna, according to Struve, contains in 1000 parts 

 32'72 of solid matters, consisting of sulphates and chlorides of sodium, 



m=3/Lt+l and m=3fj.-\-2. The adjacent curves have, so to say, in the 

 instance above, the same tangents and circles of curvature at the points of 

 miion, so that we may be said to modulate from one formula into another. 

 The raison raisonne'e of this fact is easily explicable on a priori analytical 

 principles. 



