184 ANNUAL OF SCIENTIFIC DISCOVERY. 



coal-tar, as a source of anthracene ; but upon these points no 

 definite information has been obtained up to the present time. 

 On Artificial Alizarine, by W. H. Perkin, F.R.S., Journ. Cliem. 

 Soc., May, 1870. On iJie Artificial Production of Alizarine, by Prof. 

 E. E. Itoscoe, F.R.S., Proc. Boy. Inst., 1870. 



RIVER POLLUTION. 



The Commission appointed in 1868 to inquire into the pollution 

 of rivers, have presented to the British Parliament a very interest- 

 ing and valuable report.* The commissioners were Sir William 

 Denison, Dr. Frankland, and Mr. J. C. Morton. They class river 

 pollutions under two general heads : " sewage " and " manufactur- 

 ing refuse." The chemical difference between polluted and unpol- 

 luted water is thus defined : " Absolutely pure water is not to be 

 found in nature. Even at the moment of its condensation in the 

 atmosphere from invisible vapor to visible cloud, water absorbs 

 gases and becomes also contaminated with a fine dust which is 

 everywhere floating in the air. When it falls to the earth as 

 rain, it percolates through strata or flows over surfaces more or 

 less soluble, and dissolves, according to circumstances, quantities 

 of solid matter, varying generally from about 3 pounds to 50 

 pounds in 100,000 pounds of water. In addition to these inevita- 

 ble impurities, natural and unpolluted water is not unfrequently 

 turbid from insoluble substances suspended therein in a finely 

 divided condition. 



" The following are the chief characteristics of unpolluted 

 water : It is tasteless and inodorous, possesses a neutral or faintly 

 alkaline reaction, rarely contains in 100,000 pounds more than one- 

 half pound carbon and one-tenth pound nitrogen in the form of or- 

 ganic matter, and is incapable of putrefaction even when kept 

 for some time in close vessels at a summer temperature. 



" Of the different kinds of pollution affecting rivers, animal 

 organic matter as it occurs in sewage is that which renders water 

 not only most offensive to the senses, but most likely to injure 

 health both by its gaseous emanations and by its deleterious 

 effects when used as a beverage. Rivers so polluted frequently 

 contain from 1 pound to more than 2 pounds of organic carbon, 

 and from one-third pound to three-fourths pound of organic nitro- 

 gen in 100,000 pounds. Pollution by vegetable organic matter, 

 such as that caused by dye and print works, stands next as 

 regards offensiveness ; water so polluted being excessively un- 

 pleasant not only to the sight, but also, in warm weather, to the 

 sense of smell. It often contains in 100.000 pounds twice as 

 much organic carbon as is present in water polluted by sewage, 

 but, owing to the comparatively small proportion of nitrogen in 

 vegetable substances, it rarely contains more than one-third pound 



* First Report of the Commissioners appointed in 18G8 to inquire into tho 

 best Moans of Preventing the Pollution of Rivers. (Mersey and Ribble Basins.) 

 Vol. i. Reports and Plans. London, 1870. 



