Report on the chemical examination of several waters for the City of Boston / [Benjamin Silliman].

  • Benjamin Silliman Jr.
Date:
1845
Catalogue details

Licence: Public Domain Mark

Credit: Report on the chemical examination of several waters for the City of Boston / [Benjamin Silliman]. Source: Wellcome Collection.

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    losses are incurred by the volatilization of some- of the com¬ pounds present. We are in a great measure freed from the liability to this kind of error in the analysis of these waters because of the general absence of salts of ammonia. It has been remarked that, from the action of these waters with the silver test, it was inferred that organic acids were present. The next step of incpiiry was to ascertain whether any of the waters were alkaline or acid, or whether they were all neutral. They might be acid, either from the pre¬ sence of free carbonic acid gas in considerable quantity, or from the presence of some free organic acid ; while it is ob¬ vious that an excess of free alkaline salts would give them an alkaline reaction. A sensitive tincture of blue litmus was freshly prepared in alcohol, and five or six ounces of each water being placed in test glasses of uniform size, a few drops of the blue tincture were added to each—enough to impart a decided color. A similar portion of newly boiled and pure distilled water was also treated in the same way, as a standard of comparison. After sufficient time had elapsed—no change of color was seen in Nos. 1, 2, 3, or 4. Nos. 5 and 6 had become slightly reddened {very slightly). Nos. 7 and 8 unchanged. No. 9 was decidedly reddened—No. 10 still more so—and both be¬ came still redder on the addition of more of the test. It ap¬ peared therefore that there was a free acid of some sort in Nos. 5, 6, 9 and 10. None of the waters exhibited any alka¬ line reaction. It now became interesting to determine the nature and comparative quantity of the organic acids which were present. Berzelius, in his well known examination of the waters of the Porla well in Sweden, first made known to us the exist¬ ence of two peculiar organic acids which he detected in that water, and which had before been overlooked and confounded under the general name of u extractive matterf and various similar names. These acids he called the crenic and apocre¬ nic (from the Greek xp^, a fountain). The latter is spon¬ taneously formed from the former, and differs from it consid¬ erably in the proportion of its ingredients.^ Crenic acid is easily altered in composition, and, in the presence of air and a proper temperature, is rapidly transformed into apocrenic acid—growing brown in the operation and imparting this color to the water containing it. A striking example of this is * Hermann found crenic acid to contain, in 100 parts—carbon 40.24—hydro¬ gen 7.69—nitrogen 7.50—oxygen 44.57 ; and apocrenic, carbon 62,57—hydro¬ gen 4.80—nitrogen 15—oxygen 17.63. And the chemical formulas expressing their composition to be, respectively, C 16 H 16 NO 6 and C 14 H 14 O 3 N 3.
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