92 On supplying Cities with Water. 



contact with the iron ; we should place another gun-barrel, 

 in two pieces, at the extremity of the former; the barrel 

 composed of two pieces would serve as a refrigerant, and 

 could be opened in order to collect the metal." 



Mr. Davy informs us that he has found the above process 

 to answer perfectly. The great precaution necessary is, that 

 the potash should be as dry as possible. The metal obtained 

 is rather heavier than that procured by electricity, and seems 

 to contain a little iron: but is proper for all analytical pur- 

 poses ; so that this happy experiment of the French che- 

 mists puts it in our power to procure potassium in consi- 

 derable quantities. 



SUPPLYING CITIES WITH WATER. 



An abundant supply of good water is one of the most in- 

 dispensable requisites for the cleanliness and health of the 

 inhabitants of large towns. Till iately, collections of spring 

 water have been preferred for the purpose of supplying towns 

 by means of pipes, from its supposed greater purity. But ex- 

 perience and the progress of science have proved that spring 

 water is- far inferior to river wate fo this purpose. River 

 water contains impurities visible to the eyes — spring water 

 contains them in a state of actual solution, and therefore 

 invisible. From the former the impurities will separate 

 themselves almost entirely, by rest or by filtration; from 

 the latter they cannot be separated by means adapted to the 

 demands of common life. 



London, which is extremely healthy for its size, has long 

 been supplied with river water, and to this, more than to 

 any other circumstance, are the inhabitants indebted for the 

 health thev enjov, though few of them ever take the trouble 

 to filter the water they use, even for culinary purposes. The 

 citv of Glasgow, which, till lately, had no supply of water 

 but from wells*, has at length the prospect of an inex- 



* Dr. Ure, of Glasgow, has, we understand, been lately occupied in ana- 

 lysing the wells and mineral waters in the neighbourhood of that city. The 

 former have been found to contain a surprising quantity of heterogeneous 

 matters in solution. We hope the Doctor will publish his analyses. 



haustible 



