556 AKNUAL RECORD OF SCIENCE AND INDUSTRY. 



manufactories, besides being very rich in nitrogen, readily 

 passes into putrefaction by reason of its comparatively high 

 temperature, so that streams are covered with scum from it 

 for miles, and the fish are exterminated. The waters from 

 manufactories of starch and spirituous liquors have similar 

 properties. Washing, bleaching, dyeing, and printing proc- 

 esses generally, add to w y ater a refuse rich in organic mat- 

 ter; that from woolen and carpet manufactories being much 

 more impure, and that from silk much less impure than that 

 from cotton factories. To the preceding may be added man- 

 ufactories of chemical products and dye-stuffs generally, and 

 fat-extracting establishments; while soap-boiling seems to be 

 but slightly objectionable in this respect. Numerous plans 

 for utilizing refuse of this character from different sources, 

 and thus preventing pollution of the rivers by it, have been 

 suggested. But, besides organic matter, arsenic is frequently 

 met with, and sometimes not in trifling quantities, especially 

 in the water from soda manufactories, on account of its fre- 

 quent presence as an impurity in the sulphuric acid employ- 

 ed; and for the same reason, in part, it is also found in that 

 from dyeing establishments, as well as in part also on account 

 of arseniate of soda employed with madder colors. In wool- 

 en factories the soda and soap employed add arsenic to the 

 other contaminating matter; and, generally, whenever large 

 quantities of sulphuric acid are employed, perceptible traces 

 of arsenic may be found; it also occurs in the refuse of ani- 

 line manufactories. Free hydrochloric acid is added in large 

 quantities by soda-works, and chlorides from bleaching es- 

 tablishments; while sulphureted hydrogen and, ultimately, 

 free sulphur are frequently liberated from soda residues by 

 the action of the acid waters. 



The sewage of cities, however, with its accumulations of 

 domestic refuse, of rain-water washings from the streets, and 

 excrementitious matter, contributes the largest share to the 

 sum total of putrescible nitrogenous refuse, although its filthi- 

 ness may at times be masked by the refuse products from 

 manufactories ; while the organic contents are not rapidly 

 destroyed, as is supposed, by mixing it with twenty times its 

 quantity of river water. The remedies suggested, in connec- 

 tion with the various species of impurities, are almost with- 

 out number; prevention, principally by the separate removal 



