r 42 ; 



at the fame time, preferve it wholefoms and 

 good *. 



J. A common way of purifying water is by fil- 

 tration. Water, which is filtcrated through por- 

 ous ftones, is extremely clear and limpid j but 

 fome writers have aflcrtedj that it acquires a pe- 

 trifying quality in its paflage, which, at length, 

 may produce difagreeable efFecfts J. However 

 this may be, thefe Hones are too dear for common 

 life. 



Dr. Rotheram afierts, that one of the readieft 

 and befc methods of filtering water, is, to let it 

 run through a bed of clean fand. This is^ , he 

 fays, preferable to the filtering- Hone, as" it per-, 

 forms its work much fooner ; and the grains Qf 

 fand are of fo many different figures, that they arc 

 pretty fure to flop the progrefs of any bodies of 

 fenfible bulk, in pafTmg through them §. 



♦ Boerh. Chem. vol. i. p. 348, 



I M. Amy on Cifterns ; but fee above, p. 31. 



§ If you view ten thoufand grains of fand through a mi- 

 crofcope, you will fcarcely find tv^'o of tlie fame fize ani 

 ftiape. Rothcram's Philofophical Inquiry, p. 4S. 



^^ A friend 



