| PER CENT OF SEWAGE DESTROYED. | |
| 1. Period of 24 hours | 6.8 |
| 2. Period of 24 hours | 8.9 |
| 3. Period of 48 hours | 14.3 |
| 4. Period of 24 hours | 5.4 |
| 5. Period of 24 hours | 5.8 |
| 6. Period of 24 hours | 2.1 |
| —— | |
| Total | 43.3 |
Dissolved oxygen contained in the enclosed water was determined by boiling off the dissolved gases.
REDUCTION OF URINE BY AERATION
Urine, in proportion of one gallon (imperial) to 3,077 gallons of water, exposed to the air and briskly agitated:
| PARTS IN 100,000 PARTS. | ||
| DATE. | ORGANIC CARBON. | ORGANIC NITROGEN. |
| Feb. 17, 1874, | .282 | .243 |
| “ 18, “ | .298 | .251 |
| “ 19, “ | .244 | .255 |
| “ 24, “ | .225 | .253 |
| “ 25, “ | .214 | .259 |
| “ 28, “ | .214 | .276 |
Results show that fresh urine with a large volume of water is, under atmospheric influences, more permanent and indestructible than sewage.
The agents of destruction of sewage are:
| Infusorial animals. | Chemical Oxidation. | |
| Aquatic plants. | Dilution. | |
| Fish. | Deposition. |
Sir Benjamin Brodie, in his evidence before a former River Pollution Commission, stated: “That it was simply impossible that the oxidizing power acting on sewage running in mixture with water over a distance of any length is sufficient to remove its noxious quality; that the oxygen in the water and on its surface does not exercise any rapidly oxidizing power on organic matter.” He believed “that an infinitesimally small quantity of decayed matter is able to produce an injurious effect upon health; that if a large proportion of organic matter were removed by oxidation, the quantity left might be sufficient to be injurious to health. To destroy organic matter the most powerful oxidizing agents are required. We must boil it with nitric acid and chloric acid and the most perfect chemical agents. To think to get rid of organic matter by exposure to the air for a short time is absurd.”