10 GEOLOGICAL SUKVEY OP CANADA. 



case it. should be found otherwise desirable for the supply of the city, 

 namely, by adding to it a certain amount of wood ashes, which could 

 easily be obtained so long as wood is so largely used as fuel. In this 

 way a salubrious salt, the sulphate of potash, would be substituted in 

 the water for one which Dr. Parkes, the well-known writer on sanitary 

 science, says should not exceed three grains to the gallon in a whole- 

 some water. 



stage of water The samples of water analysed by Dr. Edwards were collected after 

 were 11 collected, a long term of dry autumn weather, and at a time when both rivers 

 were rather low. They would, therefore, represent the average com- 

 position of the streams better than if they had been collected at any 

 other season. During the spring freshet the waters would contain a 

 larger proportion of organic matter relatively to the mineral salts, in 

 summer they would be affected locally and temporally by the wash 

 from thunderstorms, while during the winter they would be excep- 

 tionally pure. 



I might mention in connection with this subject that the same year 



in which I brought home the above samples of water, I collected speci- 



r'e A ion ^drained mens °^ ^e white efflorescing salt or "alkali" which every traveller 



b y i e he Assini " observes around many of the lakes and covering the dry beds of ponds 



in the region drained by the western branch of the Assiniboine, and 



found that it consists principally of sulphate of sodium and magnesium, 



together with chlorides of calcium and sodium. 



improvement As to the possibility of improving either of these waters before dis- 



of the water. .. - . . * . . J . jT ° , ., 



tributmg them m the city, 1 may remark that, while much of the 

 coarser matter held in suspension might be thrown down in settling 

 ponds, a portion of it is so very fine that it cannot be got rid of in this 

 way. The turbid water of the Eed Eiver imparts a muddy appear- 

 ance to the whole length of Lake Winnipeg, notwithstanding the 

 immense volume of clearer water supplied by the Winnipeg Eiver, 

 and along with the milky Saskatchewan it is discharged by the Kelson 

 Eiver into the "sea — still very muddy — 700 miles from the city of 

 Winnipeg. 

 PiltratioD. Filtration is the only effective remedy for this defect, and in addi- 



tion to the sand and gravel for removing the mechanical impurities, 

 there should be a layer of animal charcoal for eliminating the organic 

 matters. Such a provision would add comparatively little to the cost 

 of filtration, since this substance is found in practice to act efficiently 



in such cases for a great length of time. Unfiltered river waters, 

 Propagation of . ° • ° '■ 7 



diseases. more than any other kind, are frequently the medium for propagating 



such diseases as typhoid fever, cholera, diarrhoea, dysentry, internal 



parasites, &c, by means of the living germs which they contain, and 



