Water supply : considered mainly from a chemical and sanitary standpoint / by Wm. Ripley Nichols.

  • William Ripley Nichols
Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: Water supply : considered mainly from a chemical and sanitary standpoint / by Wm. Ripley Nichols. Source: Wellcome Collection.

    83/252 (page 69)
    while there do exist compounds of chlorine which are insoluble in water, and other compounds which are gaseous, and while it is true that chlorides are absorbed to a limited extent by earth filters and by growing plants, for all practical purposes we may say that the chlorides once dissolved in the water are not removed either as insoluble or gaseous compounds. If, now, we take the case of the Blackstone River as instanced in Table IX, page 62, we shall see that the 3.80 parts of chlorine in Mill Brook have become 0.92 part five miles below, after the brook has been merged in the river, and twenty miles further still the river water contains only 0.36 part. Believing, as we do, that this decrease of the chlorine is due almost entirely to dilu- tion, we must believe also that the decrease in the amount of the organic matter is largely due to the same cause. Owing to the fact that the organic matter is much more liable to conversion into insoluble and volatile compounds, no one would deny that an appreciable amount of organic matter is chemically changed and actually destroyed, but emphasis should be laid upon what we believe to be a fact—namely, that the apparent self-purifica- tion of running streams is largely due to dilution, and the fact that a river seems to have purified itself at a certain distance below a point where it was certainly polluted, is no guaranty that the water is fit for domestic use. Referring again to Table IX, it would appear that no effect is produced upon the waters of the Merrimack by the cities of Lowell and Lawrence, which throw into the stream the greater part of their sewage and the waste from all the mills. Is the organic matter of all this refuse destroyed by oxidation or other chem- ical change ? Certainly not! Let us take simply the results of examination above and below Lawrence. Between these two points the river receives the refuse from nearly all the manufac- turing establishments, a large proportion of the excreta of the factory operatives, and a portion of the sewage of Lawrence. Moreover, the lower station is so short a distance below the city, that no chemist, probably, would believe that any considerable destruction of organic matter could take place in the rapid flow for so short a distance, and if, upon chemical grounds, the evi- dence was not sufficient, the floating soap-suds, with still unbroken bubbles, and other materials borne down upon the current show the same thing. Now, in spite of this addition, which must be