362 THE ISOCHLORS OF NOVA SCOTIA. VICKERY. 



difficult, the control was itself clouded by titrating it nearly 

 to the endpoint, and using this as a standard of comparison. 



For the purpose of collecting samples, a number of new 

 ten and sixteen ounce bottles were provided and fitted 

 with new corks. These bottles were invariably rinsed three 

 times with the water being collected before being finallj^ 

 filled, and these bottles were used for no other purpose save 

 collecting water samples. 



Wherever possible samples were taken from small brooks, 

 usually at a distance of some forty to fifty yards from the 

 road, and from a portion of the brook where the water was 

 running heely. The greatest care was observed to avoid, 

 as far as possible, portions of the brook used b}^ animals, and 

 when a brook ran through a meadow, it was followed up to 

 the woodlands, where running water was obtained. 



It was noticed that a large lake, which has no obvious 

 source of pollution, shows a chlorine content as low, or lower, 

 than small brooks running into it. In other words, a large 

 lake gives a normal chlorine for that vicinitJ^ For example, 

 the northern arm of Lake George, in Yarmouth County, 

 has a chlorine content of 10.0 parts per million, while a 

 small brook discharging into the lake gave a chlorine content 

 of 10.2 parts per million. Milton Ponds in Yarmouth County, 

 in June, 1914, gave 13.0 parts per million, while several 

 brooks running into the ponds ranged from 15 to 20 parts 

 per million. In explanation it might be said that Milton 

 Ponds are surrounded by farms. Grand Lake, in Halifax 

 County, showed 4.1 parts per million, and as it was found 

 impossible to obtain a sample from a brook discharging into 

 Grand Lake, it was thought reasonable to assume that 4.1 

 was the normal for that vicinity. 



This observation was later confirmed by noticing that 

 the United States Geological Survey in the examination of 

 waters in New England, frequently made use of determinations 



