﻿ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 103 



an increase of nitric acid from 218 to 457. Oxidation to an important 

 degree is shown in this case, but the result is not altogether favorable 

 to the efficiency of aeration. In observations made on the River Lim- 

 mat before and after passing through Zurich the following were the 

 results : 



Outflow from lake 



station 1 



Sewer outlets 



Station 4 



Station 5 



Station 6 



Station 7 



Station 8 



Station 9 



Distance 

 in kilo- 

 meters. 







1.86 



2.175 



2.485 



2.796 



3.417 



5. 903 



6.214 



8.078 



^Number 

 of bacteria 



per cubic 

 centimeter. 



225 

 1,731 

 296, 670 

 12, 870 

 10, 892 

 5,902 

 4,218 

 2,346 

 2,110 



Miquel found iu the Seine above Paris a rate of 4,800,000 microbes 

 in the liter; below Paris, 12,800,000; in sewer water, 80,000,000. 



Instances of outbreaks of typhoid through the use of river water 

 contaminated miles above the intake are not rare. Gloucester suffered 

 by the poisoning of the river by Kidderminster, 20 miles higher up. 

 A single case of typhoid produced the disease in a Scottish town by 

 the drawing back up the course of the river, owiug to the obstruction 

 of a weir, of the sewage which had entered below. At Providence, 

 E. I., an epidemic was caused by the very slight pollution of a large 

 and rather rapid stream 3J miles above the intake. When Lowell, 

 Mass., has had a fever outbreak, Lawrence, lower down, has had a 

 similar attack a little later. The Merrimac River has given several 

 instructive examples of tyi^hoid following pollution, and the Schuylkill, 

 which is contaminated many miles above the intake of Philadelphia, 

 appears to be the chief cause of the prevalence of the disease in that 

 city. 



Experiments on the artificial aeration of water by the Massachusetts 

 Board of Health, and on natural aeration below Niagara Falls by Pro- 

 fessor Leeds, show that little or no diminution of organic particles, and 

 no chemical purification, is brought about. 



Dr. Percy Frankland has found that various disease-causing bacilli 

 present no uniformity in their behavior in potable water. Many pre- 

 serve their vitality for a considerable time — days and weeks — and some, 

 which form spores, for an indefinite time. Gafi'key's typhoid bacillus 

 preserves its vitality even in distilled water for about fourteen days. 



Altogether, aeration can not be trusted as effectual in rendering pol- 

 luted water fit for drinking, and the diminutiou of organisms which to 

 some extent does take place must be attributed to other causes. 



