.52 THE DOMESTIC WATER FILTER. 



and now am obliged to drink tap water that has been boiled. 

 The boiling may destroy any organisms that are in it, but cer- 

 tainly does not improve the taste or smell of the water, nor cause 

 any appreciable precipitation of the suspended matter ; on the 

 contrary, the peaty taste of the Enoggera and Gold Creek waters 

 is intensified and they are rendered more acrid. Some weeks ago 

 the Mount Crosby water was turned on, and for some time it was 

 very muddy, but gradually cleared and became bright, and after 

 boiling was quite palatable, but when it had arrived at this stage, 

 and I was congratulating myself that my troubles respecting 

 drinking water were at an end, for a time at all events, the next 

 morning, to my chagrin, on turning the bath -tap muddy water 

 issued from it and has continued to do so, with a slightly varying 

 degree of intensity since. It is highly desirable to obtain 

 drinking water as free from suspended impurities as possible, 

 even if it cannot be freed from dissolved matter and bacterial 

 organisms, and for that reason the use of the ordinary filter is 

 not to be despised altogether. And possibly in the case of a 

 fresh charge of pure charcoal or other medium employed, careful 

 boiling of the water before filtering may preserve the filter from 

 bacterial contamination for a time. But in order to do that, the 

 filtered water should be drawn off and used as soon after filtra- 

 tion as possible, otherwise it may become inoculated with some 

 pathogenic organism from the air, and serve as a means of 

 conveying the organism to the filtering material ; whereas in 

 the case of charcoal filters, it will find suitable conditions for its 

 development, and then become a source of infection to all the 

 water which may be passed through the filter. The experiments 

 above referred to, conducted by Dr. Sims Woodhead and Dr. 

 Cartwright Wood show how different filtering media may serve 

 as breeding grounds for disease-producing organisms. I will 

 not weary you by detailing these experiments at length, but will 

 merely state the results. 



In these experiments the filter was first carefully sterilised, 

 and repeated charges of tap water passed through it. The 

 number of organisms per cubic centimetre originally present in 

 the tap water was first determined, and the filtrate examined 

 from time to time. Samples of the first water passed were poor 

 in organisms, owing to the greater number being arrested in the 



