Mr. West on Natural Waters. 41 



very much discoloured. Where such water, then, must be 

 used, (and from its softness it has many advantages,) a well- 

 arranged and well-managed filter is highly desirable. 



It may serve to shew how cautious we should be in attri- 

 buting mistakes on scientific points to any writer, from minute 

 criticism of the terms used, to notice that, in an official report 

 from one of the most eminent chemists of the present day, it 

 is stated that the yellow or light-brown peaty water is not, in 

 his opinion, objectionable for * any domestic purpose.' He 

 undoubtedly used the term in a limited sense, confining it to 

 the preparation of food, and to its power as a simple detergent, 

 without taking notice of the probability of its leaving a colour 

 of its own. Again, the Commissioners of 1825, on the Supply 

 of Water to the Metropolis, in their able report, say, It must, 

 however, be recollected, that insects and suspended impurities 

 only are removed by filtration ; and that, whatever substances 

 may be employed in the construction of filtering-beds, the 

 purity of the water, as dependent upon matter held in a state 

 of solution, cannot be improved by any practicable modification 

 of the process/ &c. &c. Now this, as I have proved by expe- 

 riment, is not applicable to some dissolved animal and vegetable 

 matters : it can only be strictly true as applied to the salts con- 

 tained in water ; and though undoubtedly correct in the general 

 as to these, yet exceptions are still possible. 



Besides the superiority of filtering over mere subsidence, for 

 the mechanical separation of impurities, I think enough atten- 

 tion has not been paid to the power of alumine to separate both 

 animal and vegetable matter, however perfectly dissolved. I 

 evaporated deep-coloured peaty water, previously filtered and 

 very bright, and obtained at the rate of 1.6 grains from one 

 pint. On calcination, these 1.6 grains were reduced to 0.6. 

 About 0.8 grains of the quantity thus dissipated was vegetable 

 matter ; 0.2 or upwards was carbonic acid, from carbonate of 

 lime. I then separated the colouring matter by well-washed 

 alumine ; the water was left perfectly limpid : on evaporation 

 it left one grain, which, on calcination, became 0.6, as before : 

 allowing for the carbonate of lime decomposed by the heat, 

 not less than four-fifths of the vegetable matter had separated 

 in combination with alumine. 



