78 PROCEEDINGS OF THE AMERICAN ACADEMY 



V. 



ON A PRACTICAL TEST OF THE CONDITION AND 

 COMPOSITION OF NATURAL WATERS. 



By Aug. A. Hates, M.D. 



Read, April 14, 1874. 



Early in the winter of 1860 I made a verbal communication to the 

 Academy on a mode I had devised for testing tlie composition and 

 characters of waters at rest or in motion. The illustrations were 

 drawn from the then condition of Mystic Pond, as a source of supply 

 of potable water to the city of Chaiiestown. 



The somewhat novel condition of the pond led me to ask for more 

 time in continuing observations on one source of the water; and, as 

 extensive changes of flow would result from the works to be con- 

 structed, it was foreseen that some years must elaj)se before replies to 

 one or two questions arising could be given. 



At that time I stated that the earlier analyses of the water made by 

 myself and others showed that the water at the bottom contained the 

 salts and compounds of sea-water ; Avhile a considerable depth of the 

 surface water was adapted, through ordinary purity, as a source of 

 supply, while flowing as a stream. 



The saline water at the bottom might be the infiltration from sea- 

 water at a higher level, or possibly an overflow at times of high water, 

 which the dam did not prevent. The source of this water could be 

 determined after the construction of the new works, and subsequent 

 observations and analyses. 



It is a frequent remark that ponds and lakes are but enlargements 

 and broadenings of rivers ; but there are few cases only of its truthful- 

 ness of application. Here we had streams of quite pure water poured 

 into a basin, the bottom of which contained saline water, unfit for 

 domestic purposes. 



The success of the public works to be erected for the supply of 

 potable water was deemed by the commissioners and engineer as de- 

 pendent on a suppression of the contaminating water, and the continu- 

 ous flow of pui'er water above it. Further doubt was involved in the 

 solution of the question, arising from the cooling of the surface in the 



