182 



Nos. 23, 24 and 26 are from wells of from 14 to 25 feet in depth, dug in a light, 

 gravelly soil, and all more or less contiguous to contaminating sources, as stables 

 and privies. Their analyses, standing by themselves, would not absolutely condemn 

 them for use, though they would not be considered " first class." These wells, how- 

 ever, are evidently fed fiom the Bow River by infiltration, and a comparison of the 

 analytical data of the latter water (No. 25) clearly shows that these waters receive 

 pollution to some extent. 



No. 25. Drawn from the Bow Eiver, near Calgary ; clear; no debris; a good 

 water. 



No. 27. Depth of well, 12 feet 6 inches, in gravelly clay with limestone bottom. 

 Distance from house, 30 feet; from hog yard, 130 feet; from barn, 300 feet. Most 

 probably receives soak age from hog yard through crevices of the rock. 



No. 28. Well, 42 feet deep, in sandy and gravelly soil. Distance from barn, 120 

 feet; average depth of water, 8 feet J 60 feet from closet. A clear, bright water^ 

 with no deposit, but veiy badly polluted, making it unfit for use. 



No. 29. Creek water; no sewage contamination; contains suspended vegetable 

 matter, which should be removed by filtration. 



General Eemarks on Waters and "Water buppLiES. 



The chief impurities found in drinking waters, as detected by chemical analysis, 

 are of an organic nature, and arise from the presence of decomposing animal or 

 vegetable matter, or both. The former is to be regaided as the more deleterious of 

 the two, and comprises the solid and fluid excreta of animals, and decaying animal 

 matter ; vegetable pollution consists of peaty matter — the more or less decomposed 

 remains of plants. Although vegetable matter is not as injurious as that of animal 

 origin, an excessive quantity is very apt to cause diarrhoea and kindred complaints. 



Whether the organic matter itself always acts in the water as a poison or not 

 is yet a question open for discussion, though there seems to be ample evidence that 

 in many instances active organic poisons are developed by the decomposing matter. 



It has, however, been well established that it is the organic matter of a water 

 that forms the food for the growth of bacteria — microscopic plants, among which 

 are the disease germs — and cases of typhoid (a germ disease) have been repeatedly 

 traced to drinking water surcharged with organic matter. 



for these reasons we may safely conclude that a water containing much organic 

 matter must be more dangerous to health than water comparatively organically 

 pure. 



It is of the first importance, therefore, to discover the degree to which any 

 water may be contaminated by organic matter and to endeavour to establish whether 

 such be vegetable or animal. 



The amounts of free and albuminoid ammonia, of the oxygen absorbed in fifteen 

 minutes and four hours, and of chlorine, are a measure of the organic impurities of 

 a water. 



Large quantities of free ammonia associated with a considerable amount of 

 chlorine prove contamination with sewage. 



Small quantities of free ammonia and chlorine and high amounts of albuminoid 

 ammonia and " oxygen absorbed" indicate vegetable pollution. 



The presence in considerable quantities of nitrogen in nitrates and nitrites— 

 especially in shallow wells — indicates previous sewage contamination. 



When the ratio of oxygen absorbed in 15 minutes to that absorbed in 4 hours is 

 as 1?:2, dissolved vegetable matter is indicated ; when this ratio approaches 1 : 1*5, 

 the presence of animal oi'ganic matter is shown. A water contaminated with vege- 

 table matter will absorb or use up more oxygen than one polluted with animal matter. 



The bright and clear appearance of a water is no guarantee of its wholesome- 

 ness. Many badly polluted waters are sparkling and cold. 



As every water must be judged according to its source and surroundings, it is 

 impossible to lay down rules that could be applied rigidly in every case, though it 



