]82 MICRO-ORGANISMS IN WATER 



intended for drinking, and thus to dispense entirely with 

 filters, or, at most, to use them only for aerating the 

 water after boiling, and so remove the flat and vapid 

 taste possessed by boiled water. It will be of import- 

 ance, therefore, to enquire as to what is the effect of 

 high temperatures upon bacteria in water. Miquel 1 

 gives the following tables, which show that it is be- 

 tween 14 C. and 50 C. that the majority of the micro- 

 organisms are destroyed. But this diminution must 

 necessarily depend upon the nature of the microbes 

 present in the water, micrococci being far more readily 

 destroyed than bacilli, whilst some bacilli, again, are 

 far more resistant to high temperatures than others. 

 Miquel sums up his results with the following reas- 

 suring remark : ' De cet ensemble de faits, on peut 

 conclure qu'en 1'absence de filtres parfaits, on debarrasse 

 les eaux suspectes de presque tous les microbes qu'elles 

 renferment en les chauffant durant quelques minutes. 

 L'experience ayant demontre, d'autre part, qu'il n'existe 

 pas de bacteries pathogenes dont les germes puissent 

 resister a 100, on peut conclure que 1'ebullition 

 prealable des eaux est un moyen prophylactique cer- 

 tain contre les epidemics qui out pour origine la diffu- 

 sion des bacteries par les eaux potables.' 



Bacterial Condition of different Waters when heated* to various 

 Temperatures during 15 minutes (Miquel) 



Seine Water 



Temperature Number of 



maintained Microbes in 1 c.c. 



20 C 464 



45 C. during 15 minutes . . 396 



55 C. . 33 



65 C. . 20-8 



75 C. .... . 9-6 



85 C . 6-6 



95 C. .... . . 2-8 



100 C . 3-3 



1 Analyse nticrof/fapJ/ique des Eau-r. Paris, 1891. p. 180. 



