MINERAL WATERS. 



587 



wUe in solution, precipitate the lime by carbonate of 

 magnesia, and weigh the precipitate ; then throw down 

 1 the iulphiiric acid, and ascertain its quantity ; subtract 

 from it that which belongs to the lime, obtained by the 

 former precipitation ; the remainder gives the quantity 

 of.ulphate ot rnagnecia, 100 of acid uniting with 50 of 

 magnesia. If the fluid contain sulphate of magnesia 

 ana sulphate of soda, add soda, ami the magnesia will be 

 precipitated. Dry it and weigh it, 100 = 300 grains of 

 dry 'ulphate of magnesia. If the fluid contain these three 

 sulphates, add soda, by which the lime and magnesia 

 will be precipitated. Dissolve the precipitate in dilut- 

 ed sulphuric acid, and evaporate to dryness ; wash the 

 re-idue with a little cold water, which will dissolve the 

 salphatte of magnesia, and leave the sulphate of lime. 

 Evaporate the solution, and weigh the residue ; this is 

 the weight of the sulphate of magnesia, the weipht of 

 the undissolved matter is that of the sulphate of lime. 

 Should the water also contain sulphate of alumina, the 

 precipitate given by the soda must be treated with ace- 

 tic acid, which will di*solve the magnesia ; the magne- 

 sia may then be precipitated by soda. If sulphate of 

 iron be present, expose the fluid to the air for some 

 days, and add alumina, the oxide of iron, and the sul- 

 phate of alumina are precipitated, and the sulphate of 

 roagnem is left, and may be procured as above. 



87- Sulphate of Iron. Having ascertained, by boil- 

 ing. that the iron is not in union with carbonic acid, 

 precipitate the iron, (53.) and infer the quantity of suU 



88. MmruUn. Suppose that the carbonate* are thrown 

 down by boiling, and that muriates of lime, magne- 

 sia, and alumina are pits* lit, add baryta, by which the 

 whole of the three earths will be precipitated. Dis- 

 solve the precipitate in muriatic acid, and then ascer- 

 tain, by the tests, (4*, 50, 51.) the quantity of each 

 earth, and infer that of the muriate of each. 



100 lime = 196 dried muriate of lime. 



100 magnesia = 238.3 dried muriate of magnesia. 



100 alumina = 317. <> dried muriate of alumina. 



89. When the sulphates are present with the muriates, 

 the latter mint be separated by evaporation to dry-nets, 

 and treating the residue with alcohol, which will dis. 

 solve the muriates ; then proceed as above. If sul- 

 phate of lime only be present, throw down the sul. 

 phuric acid by baryta, and ascertain its quantity, filter 

 the fluid, and proceed as (88.) subtracting the quantity 

 of the mlphate of lime, iVum the lime obtained by 

 precipitation, the remainder belongs to the muriatic 

 acid. 



90 When sulphates of lime and magnesia, and the ma. 

 nates of soda, magnesia, and alumina are present, throw 

 down the lime and alumina by carbonate of magnesia, 

 an ! ascertain the quantity of lime which will give that 

 of the sulphate, (ri2.) Find out the quantity of sul- 

 phuric acid by baryta ; subtract the quantity which we 

 know was in union with the lime; the remainder will 

 belong to the matjnt -m, and will shew the quantity of 

 the sulphate of that earth. 



91. To another portion of the water, add lime-water, 

 which will throw clown the mngnrsiaand alumina; as- 

 certain the proportions of these, (6>.) that of the alu- 

 mina will shew the quantity of muriate of alumina. 

 (88.) -Subtract from the weight of magnesia that which 

 we know to belong to sulphuric acid, the remainder 

 will indicate the quantity of muriate of magnesia. By 

 adding baryta, and then carlxmic acid, to the fluid, 

 the sulphuric acid and lime will be thrown down, and 



the quantity of muriate of soda may be ascertained by Mineral 

 evaportion. ^""^ 



Sucti are the various methods which have been re- 

 commended for ascertaining the nature and quantity 

 of the different compounds contained in mineral wa- 

 ter<. It is doubtful, however, if, by these means, we 

 arrive at the exact quantity of the different substances, 

 and it is still more doubtful if we really procure them 

 in the state of combination in which they exist in the 

 mineral water. 



It has been already remarked, that little reliance can 

 be placed in the knowledge derived from incompatible 

 salts as some salts which decompose each other, when 

 their solutions are concentrated, exist together in solu- 

 tion, if a large quantity of the solvent be present. 



This subject has been lately particularly investigat- 

 ed by Dr. Murray. From numerous experiments he 

 has found, that salts, different from those known to be 

 in solution, can be obtained by the evaporation of the 

 solvent. This has induix-d him to call in question the 

 accuracy of the> modes of analysis explained, and to pro- 

 pose another method of determining the state of combi- 

 nation of the ingredients of mineral waters. See Trail- 

 tad tuns of the Royal Society of Miiihuish, vol. vii. 



.rding to Dr. Murray, two views may be enter- 

 tained with re|*ct to the state of combination of sa- 

 line substance* dissolved in water. When we have 

 two acids and two bases contained in this fluid, these 

 may be united by the pure force of the affinity, and 

 those substances between which the most powerful at- 

 traction is exerted, will be combined. Thus, suppose 

 muriatic and sulphuric acids, and soda and lime, be 

 dissolved in the same fluid, if the pure force of the af- 

 finity operate, the compounds formed will be sulphate 

 of lime and muriate of soda. We know, however, 

 that affinity is much influenced by external circum- 

 stances ; when, therefore, any of these operate, com- 

 pound* mi.y be formed, different from those which 

 the pure force of the affinity would generate. When 

 the above mentioned substances are dissolved in 

 small quantity of water, the compounds stated are 

 formed, Nit if the quantity of fluid be great, it is 

 possible that it may, by its quantity, influence the 

 affinity, and other compounds will be the result. When 

 the quantity of fluid is small, or when we evaporate 

 the fluid by which the cohesion is allowed to operate, 

 we find invariably that the compounds existing in the 

 water, sre thote, between the particles of which the 

 strongest cohesion is exerted. The reverse, it is pro- 

 bable, is the case, when the quantity of water is great, 

 the quantity of the fluid causing the formation of sub- 

 stances, between the particles of which there is little 

 power of cohesion, so that the most soluble salts are 

 formed. When the above mentioned substances, then, 

 are dissolved in a large quantity of water, instead of 

 sulphatp of lime, and muriate of soda, we will have mu- 

 riate of lime and sulphate of soda. Thr same it it sup- 

 posed is the case, when carbonate of lime and muriate 

 of soda are procured by evaporation, these salts having 

 been formed, by the decomposition of the carbonate of 

 soda and muriate of lime, which were the salts tint ex- 

 isted in the water, when large quantity of the solvent 

 was present If carbonate ofrnagnesia and muriate of 

 soda be procured, the salts in solution were probably 

 carbonate of soda and muriate of magnesia. In all mi- 

 neral waters, the quantity of fluid is large in propor- 

 tion to the saline ingredients ; these, therefore, are pro- 

 bably united, so as to form the most soluble salts. 

 This view of the state of combination of the substan- 

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