720 Proceedings of the Royal Irish Academy. 



ate of lime and of carbonate of magnesia is about equal. These ai'e 

 the only analyses of water I have seen in which the amount of mag- 

 nesian salts at all approaches that of the lime salts. 



In the valuable abstracts of chemico-mineralogical papers pub- 

 lished in the Journal of the Chemical Society, from toI. ix. to vol. 

 xiv., inclusive, I find very many analyses of mineral waters, with one 

 or two exceptions European, ordinaiy river water, chalybeate and 

 thermal spiings, &c. In all of these the carbonate of lime is in great 

 excess of that of magnesia; the chlorides also occupy the same relative 

 position. In all these analyses there is no instance to the contrary. 

 The proportions are very variable of course, in some cases carbonate 

 of magnesia being altogether absent. The lowest proportion in which 

 it is stated in any of these is *•' 



Carbonate of lime, 145 



,, magnesia, 7 



The highest is,t for total lime and magnesia salts : they are cal- 

 culated only as oxides — 



Lime(CaO.) 74-94 



Magnesia (MgO.) 20-54 



and the average proportion appears to be about 14 to 1. 



About thirty or forty analyses are included in the above resume. In 

 no single instance was carbonate of magnesia in excess of carbonate 

 of lime. All these scattered analyses are the more valuable in their 

 agreement on the point I am urging, from their authors having, appa- 

 rently, no particular theory to bring forward, and, though taken at 

 random, the persistence in the larger amount of lime salts is very 

 marked. I may now refer to the capital table of analyses of river 

 waters given by Bischof,| which includes forty-eight examples, in 

 every one of which carbonate of lime is very largely in excess of that 

 of magnesia. These range as follows : — 



Carbonate of lime, . . 1-28 to 18-23 | In 100,000 

 ,, magnesia, . 0-09 to 1-47 | parts. 



In many cases no carbonate of magnesia is recorded at all, even 

 where the corresponding lime salt is so high as 26-2, nor is there in 

 any case a large proportion of the more soluble salts of magnesia, sul- 

 phate, or chloride. This shows, therefore, that carbonate of magnesia 



* Chalybeate spring at Sellafield, near "WTutehaven. "W. H. "Watson, Chem. 

 News, xxxii., p. 11. Abs. Joiir. Chem. Soc, vol. xiii., p. 1169. 



t Ehine water, near Kohi, Dr. Yohl, Abs. Jour. Chem. Soc, vol. ii., 

 pp. 213-14. 



+ Op. cit. l, pp. 76, 77. 



