THE A N A L Y S T . OCTOBER, 1878. ON THE IRCONSTANT COMPOSITION OF WELL WATERS. By CHABLES A. CAMERON, M.D., Fellow and Professor of Hygeine and Chemistry, R.C.S.I. ; Medical Officer of Health for Dublin. Read before the Society of Public Analysts, at Bublin, 19th August, 1870. FOE some time past I have been engaged in examining the water of deep wells, and I have noticed the important fact that very often the water varies in composition a t different levels in the same.Well, the most remarkable instance of this kind which I have, up to the present discovered, is that afforded by a well at Glenfarme Hall, near Enniskillen, the residence of Mr. A. Loftus Totterham, D.L. Two speoimens of water taken out of this well, one a few minutes after the other, mere found to have the following composition :- No.1, No, 2, Grains. Grains. Total solids per gallon . . . . . . . . . . . . . . 29.012 - 47’40000 Albuminoid Nitrogen . . . . . . . . . . . . . . . 0%26 - 0.0060 Saline Ammonia . . . . . . . . . . . . . . . . . 0.010 - 0.0003 Chlorine . . . . . . . . . . . . . . . . . . . . . 2.137 - 1,795 Including- The water marked No. 1 was yellowish and very impure.It wa3 in fact a very bad water. No. 2, on the contrary, wa8 colourless, bright, and remarkably free from organic matter. I n this case, therefore, a bad water and a good one were simultaneously procurable from the one well. The bad water was obtained by dipping a vessel into the well; the good water was pumped up from the bottom of the well, which was more than 50 feet deep.It was clear that the lower part of the well was supplied with water derived from springs; or, at any rate, which had percolated through a large amount of soil and had become purified, so far as ite organic matter was concerned. The upper part of the woll contained surface drainage, which appears to have floated upon the somewhat heavier water beneath. Specimens of water were a second time procured from this well, and again it was found that the water near the bottom was harder and purer (from organic matter) than that near the top.In four waters from deep wells, which I have quite recently examined, I found that the composition of the water in each varied somewhat according to the depth. I n one case the solids amounted to 66-23 grains per gallon at the bottom of the well, whilst nemer the surface the solids were only 3 grains per gallon. We may, in short, have two kinds of drainage water collected in the same well,-namely, surface drainage, and arterial or deep drainage. It does not, however, always happen that the water in a deep well varies in quality according to the level at which it is collected, for I found no such variation in the waters bf several very deep wells. It was very much harder than No. 1.