The following table contains the analyses of the city water used for filtration in 1891. The earlier analyses, from Nov. 17, 1887, to Dec. 31, 1889, were given in the special report upon the Purification of Sewage and Water, page 618, and from June, 1889, to Dec. 31, 1890, in the annual report for 1890, page 170. Weekly Analyses of City Water as drawn at the Lawrence Experiment Station. AMMONIA. NITROGEN AS April 1, 38° V. slight, 8, 38 V.elight, V. slight, .18 .0042 .0072 .16 .0260 .0000 .19 15, 41° V. slight, .0064 .0070 .16 .0170 .0000 .0040 .0070 .15 .0190 .0000 .23 .19 .0030 .0086 .13 .0180 .0000 .27 .33 1.24 1.30 117 1.23 1.32 104 5 1.20 1.32 1.29 1.33 40 1.05 1.22 44 .93 1.17 98 Consumed. Oxygen Weekly Analyses of City Water as drawn at the Lawrence Experiment Station -Concluded. The following table contains the analyses of the canal water applied to Filters 8 and 18 A. It is brought through a small pipe, about four hundred feet long, from the canal of the Essex Company, and is substantially the same as the Merrimack River water above Lawrence, and as the water pumped into the city reservoir. It differs from the city water as drawn at the experiment station in containing more suspended matter and a much larger number of bacteria. DATE. Weekly Analyses of Canal Water as drawn at the Lawrence Experiment Station. The full results of the weekly analyses of the effluent of Filter Tank No. 8 are given in the following table. The numbers for bacteria given are the regular weekly counts; a more extended account of the numbers and of the various species found will be given subsequently in the report of the biological work of the station. City water applied 18 times a week till January 11, 12 times a week January 13 to March 24, and afterwards 6 times a week. March 18, straw, leaves and other material removed and surface levelled. 29, 0 May 6, 0 .0014 .0068 .14 .0260.0000 .08 9 .0006 .0068 .14 .0360 .0000 .11 2 13, 0 .0018 .0058.13 .0360.0000 .10 8 20, 0 .0008.0046.12 .0320.0000.09 11 27, 0 .0008.0064 .13 .0300 .00 00 .09 10 |