Recent Progress in Sanitary Science. 287 



together with " the refuse waters of 36 woollen mills, 23 cotton mills, 6 

 iron works, a tannery, and a slaughter-house — these works employing 

 7,200 hands," a total of 006,508 cubic feet per diem of badly polluted 

 water. This would amount to about l-10th of the entire dry- weather flow 

 of the river at Blackstone, a town located near the southern bound- 

 ary line of the state. A sample taken from the Gate-House of the City 

 Reservoir on Lynde Brook, one of the head waters of the Blackstone, 

 contained in 100,000 parts, 0.0235 parts of proteine matter, and 1.96 parts 

 of organic, requiring 0-504 parts of oxygeu to effect oxidation ; while the 

 waters of the Blackstone near the state line, after a flow of about 20 miles 

 beyond Worcester, contained 0.0128 parts of proteine matter, 1.72 parts 

 of organic, and required but 0.320 parts of oxygen to decompose the 

 organic impurities. 



We must conclude, therefore, that those who have denied any power of 

 self-purification to a flowing stream, are mistaken iu this matter; and that 

 the receipt of tributary waters holding their normal percentage of dis- 

 solved ox3 r gen in solution, intestinal movement in contact with growing 

 plants and earthy oxides, and abundant exposure to light and air, should 

 be elevated to the rank of true causes in the regeneration of rivers. 

 Moreover, while it seems incredible that Philadelphia, Newark, Albany, 

 Cincinnati, and other great cities, should drink waters after pollution by 

 the sewage of towns located a few miles above them, and should do so 

 without active disease traceable to this source, yet this is a fact, and one 

 of so great magnitude that we must allow it due weight and must explain 

 it by a sufficient cause. 



Finally, while we believe the above statements to be true, yet in view 

 of what has been previously said concerning the danger from infected 

 sewage, and the deterioration of health from all sewage, we do not the 

 less look upon the pollution of waters as a monstrous evil, to be done 

 away with so soon as public opinion upon these important sanitary ques- 

 tions shall have become imperative. 



VII. Whether any means, microscopic, chemical or otherwise, exist at 

 the present time, of discriminating between Infected and Non-infected 

 Sewage ; and if, as some high authorities contend, they cannot be dis- 

 tinguished, whether sewage by one community into the water-supply of 

 another community, should not be interdicted. 



Upon this point all the best authorities have decided in the negative. 

 Moreover the matter which carries the infection may, as appears from a 

 recent case in Switzerland, be filtered through several miles of soil, and 

 escape destruction. And this too, when, as the English Rivers-Pollution 

 Commission has declared in their report of 1875, "Slow soakage through 

 a few feet of gravel destroys more organic matter than does a flow of 

 many miles in the Thames." It is unnecessary to bring to your recollec- 

 tion the great mass of testimony concerning the carrying of cholera and 

 typhoid fever by infected streams. No process of filtration, precipitation, 

 or irrigation appears adequate to destroy these germs of infectious dis- 

 eases; according to recent investigations this can be effected only by 



