50 TRANSACTIONS OF THE [nOV. 29, 



Nitric Acid, 0.45 0.54 



Total Solids, 9.00 8.70 



It will be seen that the albuminoid ammonia has diminished 

 nearly forty per cent; and, what is the most noteworthy feature 

 of all, the nitrous acid has undergone complete oxidation, none 

 being present in the aerated sample. At the same time, by oxi- 

 dation of the nitrogenous portions of the organic matter, the 

 nitric acid has been increased twenty per cent; and by oxidation 

 of the organic constituents in general, the total solids have been 

 diminished from 9 parts per 100,000 to 8.7 parts. 



The process has now been applied to the entire water-supply of 

 Hoboken, amounting to four million gallons per diem, for more 

 than two years, and during this time the unpleasant taste which 

 caused its first application has never reappeared. 



A similar experience in Brooklyn has caused the process to be 

 used in connection with the water obtained from driven wells. 

 This driven-well water has been used in the Greenwood Cemetery 

 to feed a number of artificial lakes arranged to beautify the 

 grounds. Last summer I was asked to examine the water in the 

 reservoir into which the driven-well water is first pumped, and 

 to devise a means, if possible, for preventing the enormous 

 growth of plants therein. The growth, on examination, proved 

 to be diatomacece, particularly of the species Navicula viridis, 

 and the green vegetable substance which by its decay rendered 

 the water offensive was the slime secreted by these diatoms. 

 Two facts were prominent. The one was that the diatoms could 

 be made to grow very rapidly when exposed in open jars to sun- 

 light; the other, that the water of the reservoir was very deficient 

 in dissolved oxygen. It contained only 2.32 cubic centimetres 

 of oxygen in the litre, and the enormous amount of 4.97 cubic 

 centimetres of carbonic acid. I advised the covering of the 

 reservoirs to exclude sunlight. The authorities were opposed to 

 so doing, because it destroyed the very result aimed at in provid- 

 ing the reservoir and ponds, which was to beautify the park. 

 Then I advised the use of an air-compressor. This was installed, 

 and the result is given in the following letter from the consulting 

 engineer: 



November 27th, 1886. 

 Dr. Albert R. Leeds. 



Dear Sir: — In answer to your inquiry concerning the trouble 

 at Llie Greenwood Cemetery reservoir, I would state: that the 

 water, fresh from driven wells, when delivered into the reservoir 

 began to develop decaying vegetation, which, in a short time, 

 rendered the water offensive to taste and smell; that immedi- 

 ately on receipt of your report and recommendation last June, I 

 set up an ordinary compressor, and pumped air into the mains 



