1819.] Scientific Intelligence. 471 



Philosophical Transactions. Afterwards it was analyzed again 

 by Prof. Klaproth. The result of his experiments, and the 

 animadversions on them by Dr. Marcet, may be seen in the first 

 volume of the Annals of Philosophy. A few months ago, Gay- 

 Lussac published another analysis of the same water. The 

 specimen examined was brought by the Comte de Forbin. I 

 shall exhibit the results of these three analyses in the following 

 table. The saline contents were extracted from lOOof'water. 



Marcet. 



Common salt 10-676 . 



Muriate of lime 3-792 . 



Muriate of magnesia 10-100 . 



Sulphate of lime 0-054 . 



24-622 42-60 26-24 



The specific gravity of the water examined by these gentle- 

 men differed somewhat ; depending, perhaps, upon the season 

 of the year in which the specimens were taken. The following 

 table exhibits the specific gravities as stated by each of them : 



Dr. Marcet 1-211 



Prof. Klaproth 1-245 



M. Gay-Lussac 1-2283 at 62 



)0 



I think it probable that the greater specific gravity of the 

 water examined by Gay-Lussac, together with his making an 

 allowance for the muriatic acid driven off during the exposure 

 of the muriate of magnesia to a red heat, is the cause of the 

 greater proportion of salt found by him in this water than by Dr. 

 Marcet. 1 he method of determining the true quantity of salts 

 contained in water may, at first sight, appear very easy, but it is 

 a problem attended with considerable difficulty. The method 

 which I find to answer best is to put a given weight of the water 

 into a Florence flask, the weight of which is noted, to incline 

 the flask upon a sand-bath, and to evaporate the water away. 

 I then expose the bottom of the flask to a red heat, and weigh it 

 when cold. From this it is easy to deduce the weight of the 

 saline contents, provided care be taken to add the proportion of 

 muriatic acid which may be driven off from various earthy 

 muriates (especially muriate of magnesia), if they are present. 



Klaproth's salts were not dried at a red heat. This accounts 

 for the great weight of the salts which he obtained ; and makes 

 it difficult to draw any accurate conclusions from his analysis. 

 The muriate of lime found by Marcet and Gay-Lussac nearly 

 agree. We find the same approach to coincidence in the quan- 

 tity of common salt and muriate of magnesia taken together ; 

 but Dr. Marcet found a much greater proportion of common 

 salt than M. Gay-Lussac; while, on the other hand, Gay-Lussa<* 



