of Mineral Waters. 225 



sulphate of soda, sulphate of magnesia, and sulphate of lime ; 

 digest it in ten parts of boiling distilled water, which, when 

 cold, will have taken up every thing but sulphate of lime, of 

 which an inappretiable portion only will have been dissolved ; 

 separate the solution into two equal portions, a and h. 



To a add nitrate of silver, and wash and dry the precipitate, 

 which is chloride of silver, and of which 100 parts indicate 41 

 of sea-salt. 



To b add acetate of baryta as long as it occasions a preci- 

 pitate, which is sulphate of baryta, and which is to be sepa- 

 rated, dried and weighed. 100 grains are equivalent to 60.5 

 of sulphate of soda, and to 5 1 of sulphate of magnesia. 



In order to ascertain the quantity of magnesia present, and 

 consequently the quantity of sulphuric acid belonging to it, 

 evaporate the liquid filtered off the barytic precipitate E to 

 dryness; it will contain sea-salt, acetate of soda, acetate of 

 magnesia, and, probably, a portion of the added acetate of 

 baryta ; ignite the dry mass, and wash it to separate the sea- 

 salt and soda ; magnesia and carbonate of baryta will remain 

 insoluble, upon which pour dilute sulphuric acid ; digest, filter, 

 and evaporate the clear liquor to dryness ; it is sulphate of 

 magnesia, equivalent of course to the original portion of the 

 salt ; deduct the sulphuric acid contained in it from the whole 

 in the precipitate E, and the remainder will give the quantity 

 united to the soda. 



12. To estimate the quantity of sulphate of lime in the 

 water, the residue of the evaporation of one pint may be 

 washed with cold saturated solution of sulphate of lime, which 

 will dissolve every thing but that sulphate, and which may thus 

 be obtained and weighed ; or, add oxalate of ammonia to a 

 given quantity of the boiled and filtered water, collect the pre- 

 cipitate, and dry it at a heat of 500°. One hundred grains 

 of this oxalate indicate 104 of dry sulphate of lime. 



13. Such are the general components of mineral waters, and 

 the means of ascertaining their relative quantities. Let us sup- 

 pose the following results have been obtained, with a view to 



