248 MICROBES, FERMENTS, AND MOULDS. 



bread. Spring- water, and still more river-water, as 

 it is now supplied in towns by a system of pipes, 

 is not free from organic matter, nor from microbes, 

 although they are less abundant than in well-water. 

 Purification is therefore necessary. 



With this object, it is recommended, especially in 

 times of epidemic, to boil the water, so as to destroy 

 the microbes contained in it. But this process expels 

 the gases, and reduces the proportion of salts in solu- 

 tion, thus rendering the water heavy and indigestible. 

 It has, therefore, been suggested that only weak 

 mineral waters should be drunk, such as that of 

 Saint Galmier, which, if taken at the source and 

 immediately placed in hermetically sealed bottles, 

 contains very few microbes. But this process is 

 costly, so that only rich people can avail themselves 

 of it. The most practicable mode of purifying table- 

 water and rendering it wholesome is by the use of 

 filters. 



Ordinary Filters. Charriberland' s Microbe Filter. 

 Every one is acquainted with the common filter, 

 made with crushed sandstone, charcoal, etc., which 

 should be found in all households and kitchens. This 

 generally suffices to free water from organic matter, 

 and especially from the ova of ascarides (intestinal 

 worms), which, when introduced into the system, 

 develop and cause inconvenience to so many children, 

 and even to grown persons. It is impossible to insist 

 too strongly on the fact that the presence of ascarides 



