In the Isle ofWtghK 223 



§ VII. Of the different Methods of Analysis applicable to the present- 

 Inquiry^ 



In analysing a mineral water, two modes of proceeding occur 

 from the very first. We may either evaporate the water first, and 

 apply our reagents to the soUd residue ; or operate at once upon the 

 water itself. The former plan is in general found expedient when 

 the quantity of solid contents of the water is small ; but when, 

 as in the present instance, the impregnation is considerable, it may 

 be more convenient to adopt the latter method. But at all events, 

 as the re-dissolution of the solid residue, when the first mode of 

 proceeding is resorted to, generally requires the introduction of an 

 acid, which may modify or complicate the process, it is always de- 

 sirable that both methods should be tried in succession, in order to 

 obtain comparative results. 



We may also, if necessary, precipitate from the same portion of the 

 water the several ingredients which it contains, by applying to it in 

 succession their respective reagents ; or if our supply be considerable, 

 we may use a fresh portion of it for each successive operation, a 

 mode of proceeding which is generally preferable. No difficulty 

 being experienced during the present inquiry in regard to the supply 

 of water, a variety of methods was tried, with the details of which 

 I shall not trouble the Society : but in order to convey a general 

 idea of them, and in hopes that a summary review of this kind may 

 afford some assistance to chemical inquirers not yet accustomed to 

 researches of this nature, I shall briefly enumerate the different plans 

 which presented themselves at this period of the analysis, and it 

 will be seen afterwards how these plans were gradually modified. 



\st method. To precipitate in succession from a known quantity 



