60 



ALUMINOUS CHALYBEATE SPRING IN I. OF WIGHT. 



Sect. VII. Of the different Methods of Analysis applicable 

 to the present Inquiry. 



J>ifTerrnt me- 

 thods of ana- 



"Methcis em* 



1st method. 



5«i method. 



In analysing a mineral water, two modes of proceeding 

 OCeur from the very first. We may either evaporate the 

 water first, and apply our reagents to the solid residue; or 

 operate at once upon the water itself. The former plan is 

 in general found expedient when the quantity of the 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 redissolution of the solid residue, when the first 

 mode of proceeding is resorted to, generally lequires the in- 

 troduction of an acid, which may modify or complicate the 

 process, it is always desirable, that both methods should be 

 tried in succession, in order to obtain comparative results. 



We may also, if necessary, precipitate from tne 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 por- 

 tion of it for each successive operation, a mode of proceed- 

 ing which is generally preferable. No difficulty being ex- 

 perienced 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 m order to con- 

 vey 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 na- 

 ture, I shall briefly enumerate the different plans which 

 presented themselves a<this period of the analysis, and it 

 will be seen afterward how these plans were gradually modi- 

 fied, 



1st method. To precipitate in succession from a known 

 quantity of the water, the iron by prussiate of potash — the 

 lime by oxalate of ammonia — the alumine and magnesia by 

 caustic potash, which, by boiling, redissolves the alumine 

 and leaves the magnesia untouched. 



2d method. To precipitate the iron and earths by sub- 

 carbonate oF ammonia. To evaporate the remaining clear 

 solution to dryness, and apply a red heat. To redissolve 



this 



