388 



M I N E R A L W A T E R S. 



Mimrl 



ces j n solution in a large quantity of fluid, is supported 

 by several facts. Thus by the evaporation of some mi- 

 neral waters, a quantity of a substance sparingly solu- 

 ble, as of sulphate of lime, is obtained in greater quan- 

 tity than we know water cm hold in solution. It must 

 therefore have been formed during the evaporation by 

 the operation of new affinities. It usually happens also, 

 that when this is the case, the deposition of the sub- 

 stance commences at a certain stage of the evaporation, 

 and that, after the fluid is farther evaporated, the depo- 

 sition ceases. At this point, then, it would appear that 

 the substance deposited begins to be formed. 



Another strong argument in favour of the opinion of 

 Dr. Murray, is, that different products are obtained 

 from a mineral water according to the mode of analy- 

 sis. Sea -water, for instance, by slow evaporation, af- 

 fords muriate of soda, muriate of magnesia, and sul- 

 phate of magnesia. When the fluid is evaporated to dry- 

 ness, and the residue is subjected to the action of alco- 

 hol, the products are muriate of soda, muriate of mag- 

 nesia, and sulphate of soda. It is likely then, that du- 

 ring the evaporation of the fluid new affinities may ex- 

 ert their influence, so that salts, different from those 

 which exist in solution, may be obtained. 



Many mineral waters possess active properties, for 

 which, however, we cannot account, on the known 

 properties of the compounds discovered in them. Thus 

 the Bath waters, according to the analysis by evapora- 

 tion, contains in an English pint about 9 grains of sul- 

 phate of lime, 3.3 muriate of soda, 3 sulphate of soda, 

 f s llis of carbonate of lime, fth silica, and -^th oxide of 

 iron. These are either so inert, or in so small quantity, 

 as to be incapable of producing any effects on the liv- 

 ing system. According to Dr. Murray, the true com- 

 ponent parts of the Bath water are very different. It 

 contains muriate of lime, a substance possessed of con- 

 siderable power, along with muriate of iron. The quan- 

 tity of muriate of lime, equivalent to 3.3 of muriate of 

 soda, is 3.1. A pint, therefore, of the Bath water, if 

 the views of Murray be correct, contain 3.1 gr. of this 

 active agent. If this be the case, we can perhaps ac- 

 count for its medicinal properties. 



The opinions entertained by Dr. Murray, as just ex- 

 plained, afford another method of analysing mineral 

 waters. 



In analysing a mineral water, according to the mode 

 recommended by Murray, we must first, by the use of 

 the various tests already described, ascertain the differ- 

 ent substances which it contains. We then infer that 

 these exist in it in a state of combination, so as to form 

 the most soluble salts. 



This method of ascertaining the quantity of saline 

 compounds in water, was previously employed by Dr. 

 Marcet, in his analysis of the water of the Dead Sea, 

 published in the Philosophical Transactions for 1 807. 

 Dr. Marcet, does not however state, that he supposed 

 the ingredients were so combined as to form the most 

 soluble salts. 



Dr. Murray has given the following formula, which 

 is applicable to almost all mineral waters. 

 . The four classes of mineral waters, the acidulous, the 

 sulphureous, the chalybeate, and the saline, may all be 

 reduced under the last. By the application of caloric, 

 the gaseous fluids are driven off from the two first, and 

 the iron may be precipitated from the third by its pro- 

 per test. The substances left after this are the same as 

 those contained in saline mineral waters. 



The substances which usually exist in saline mineral 

 waters, are carbonic, sulphuric, and muriatic acids, 



with soda, lime, and magnesia. Suppose that in the 

 water to be analysed all of these have been detected, the 

 fluid must be evaporated, stopping the evaporation be- 

 fore there is any deposition from it. Muriate of bary- 

 ta is then to be added, as long as any precipitate falls, 

 carefully avoiding adding an excess. If the precipi- 

 tate be soluble with effervescence in muriatic acid, it 

 is carbonate of baryta. The weight of this gives that 

 of the carbonic acid 100 gr. = 22 of acid. If the preci- 

 pitate do not effervesce with muriatic acid, it is sul- 

 phate of baryta, 100 gr. of which =r 34 of sulphuric 

 acid. If the precipitate be partially soluble in muria- 

 tic acid, it contains both carbonate and sulphate of ba- 

 ryta ; the proportions of each of which may be known, 

 by weighing the precipitate, washing it with muriatic 

 acid, and drying the residue. The weight of this gives 

 that of the sulphate, the loss that of the carbonate of ba- 

 ryta. By this means the carbonic and sulphuric acids 

 are removed, and the whole of the salts are converted 

 to muriates. Oxalate of ammonia is next to be added to 

 the filtered fluid. Oxalate of lime is precipitated, 

 which, after being exposed to a strong heat, must be 

 converted into sulphate. (62.) I00g.=4-1.5 of lime. 



The filtered fluid is afterwards to be heated to about 

 100, and reduced a little by evaporation. A solution 

 of carbonate of ammonia is then to be added to it, and 

 immediately afterwards a solution of phosphate of am- 

 monia, continuing the addition of both as long as there 

 is any precipitation, taking care to leave an excess of 

 ammonia. By the addition of these substances, one 

 part of the ammonia neutralises the muriatic acid of the 

 muriate of magnesia, the other portion combines with 

 the phosphoric acid and the magnesia, and forms the 

 triple phosphate of magnesia and ammonia, which is 

 precipitated. By exposing this to a red heat for an 

 hour it is converted into phosphate of magnesia, lOOgr. 

 of which = 40 magnesia. After this the fluid contains 

 muriate of soda perhaps with muriate of ammonia. To 

 procure the former it must be evaporated to drynesg, 

 and the residue exposed to a high temperature, 100 = 

 53.3 soda. 



The muriatic acid in the muriate of soda obtained 

 may be either greater or less than what was contained 

 originally in the fluid ; part of the soda may have been 

 disengaged from the other acids, and have combined 

 with the muriatic acid of the muriate of baryta, used in 

 the precipitation of the sulphuric and carbonic acids. 

 If this be the case, the acid in the muriate of soda pro- 

 cured will be greater than what existed in the water ; 

 or the soda may be in less quantity than could neutral- 

 ize the whole of the muriatic acid, part of this acid hav- 

 ing been combined with the other bases. If this be the 

 case, the acid set free during the addition of the ammo- 

 niacal salts, would be contained in the residue of the 

 evaporation in union with ammonia, but would be vo- 

 latilized by the heat, the muriatic acid in the muriate of 

 soda would therefore be less than the water originally 

 contained. Though the quantity of muriate of soda 

 procured therefore, gives the real quantity of the soda, 

 yet it does not afford the proportion of the muriatic 

 acid. This may be discovered, by combining by cal- 

 culation the buses with the acids, taking the quantity of 

 muriatic acid in the muriate of soda, and thus we will 

 find whether there be a deficiency or redundance of 

 muriatic acid. By subtracting the surplus from what 

 exists in the muriate of soda, or by adding the deficien- 

 cy to it, we arrive at the quantity of the muriatic acid. 

 This method is, however, liable to fallacy. It is better^ 

 therefore, to take a separate portion of the water, eva 



Mincr! 

 Waters. 



