IC-NRLF APPENDIX TO THE SEVENTEENTH ANNUAL REPORT OF STATE BOARD OF HEALTH OFJJRHODE ISLAND, FOR THE YEAR ENDING DEC. 31, 1894. REPORT OF THE RESULTS OBTAINED WITH EXPERIMENTAL FILTERS AT THE PETTACONSET PUMPING STATION OF THE PROVIDENCE WATER WORKS, EDMUND B. WESTOX, MEMBER or THE AMERICAN SOCIETY OP CIVIL ENGINEEI MEMBER OP THE INSTITUTION OF CIVIL ENGINEERS OF GREAT BRITAIN. ASSISTANT ENGINEER IN CHARGE OF WATER DEPARTMENT, PROVIDENCE, R. I. PROVIDENCE, R. I.: E. L. FREEMAN & SONS, STATE PRINTERS. 1896. EXCHANGE APPENDIX TO THE SEVENTEENTH A^NXJAL- ItEPORT^OF^ THE STATE BOARD OF HEALTH OF RHODE ISLAND, FOR THE YEAR ENDING DEC. 31, 1894. REPORT OF THE RESULTS OBTAINft) WITH EXPERIMENTAL FILTERS AT THE PETTACONSET PUMPING STATION OF THE PROVIDENCE WATER WORKS, BY EDMUND B. WESTON, MEMBER or THE AMERICAN SOCIETY OF CIVIL ENGINEERS. MEMBER OF THE INSTITUTION OF CIVIL ENGINEERS OF GREAT BRITAIN. ASSISTANT ENGINEER IN CJIARGE OF WATER DEPARTMENT, PROVIDENCE, R. I. PROVIDENCE, R. I.: E. L. FREEMAN & SONS, STATE PRINTERS, 1896, GENERAL CONTENTS. PAGE. INTRODUCTORY 1 Definition of Natural and Mechanical Filtration 1 Description of Filters Nos. 1 and 2 2 Description of Table No. 1, etc 2 Definition of "Effective Size" and "Uniformity Coefficient" 4 Table No. 1. A comparison of the Results obtained from Filters Nos. 1 and 2, and the Experimental Morison Mechanical Filter from March 27 to October 5, 1893, including Rates of Filtration, Bacterio- logical Percentages of Removal (computed from cultivations of from 42 to 62 hours), Loss of Head due to the Flow of the Water through the Filters, Percentage of Color Removed, and Quantity of Basic Sulphate of Alumina used 5 DESCRIPTION OF THE EXPERIMENTS THAT WERE MADE WITH THE EX- PERIMENTAL MORISON MECHANICAL FILTER 34 The term Morison Mechanical Filter, an abbreviation of Experimental Morison Mechanical Filter 34 Description of the Experimental Morison Mechanical Filter 34 Standard Rate of Filtration decided upon 34 Alumina, an abbreviation of Basic Sulphate of Alumina 34 Details investigated 36 Chemicals used during preliminary experiments 37 Theory of Mechanical Filtration 37 Definition of " Free Flow " 37 A proportional rise of water above filter-bed essential, in order to ob- tain a constant rate of filtration 37 Loss of Head due to " Free Flow," etc 38 Improvement in efficiency over Natural Filtration by adding Alumina. 38 Description of the Method followed in adding the Sulphate of Alumina to the Applied Water, and the Apparatus used 38 Coagulant, proportions of Alumina and Water used 38 Investigations relative to the decomposition of the Basic Sulphate of Alumina during filtration 39 Application of the Logwood and Acetic Acid test for Alum 39 Sensitiveness of Logwood and Acetic Acid test 39 Constituents of the Basic Sulphate of Alumina used. 39 Experiments with Settling Tanks 41 Time that the Samples of water were Collected to which the Logwood and Acetic Acid test was applied 41 iv GENERAL CONTENTS. Bacteriological Work : 42 Description of Tables 47 Tables showing Percentages of Removal of Water Bacteria. Table No. 2. End Growths, the Samples of Applied and Filtered Water were collected at the Same Hour 55 Table No. 3. Growths of about Ninety Hours, the Samples of Ap- plied and Filtered Water were collected at the Same Hour 57 Table No. 4. End Growths, the Samples of Filtered Water were col- lected from 1 to 9 times daily, One Hour or More after water com- menced to flow from the filter 59 Table No. 5. Growths of Eighty-five Hours or More and End Growths, the Samples of Filtered Water were collected from 1 to 9 times daily One Hour or More after water commenced to flow from the filter G5 Table No. 6. End Growths, the Samples of Filtered Water were col- lected Thirty Minutes or Less after water commenced to flow from the filter 74 Table No. 7. Growths of about Ninety Hours, the Samples of Fil- tered Water were collected Thirty Minutes or Less after water com- menced to flow from the filter 76 Table No. 8. Growths of Eighty-five Hours or More and End Growths. the Samples of Filtered Water were collected Thirty Minutes or Less after water commenced to flow from the filter 78 Table No. 9. Summary of the Average Percentages given in tables Nos. 2, 3, 4 and 5, the Samples of Filtered Water were collected One Hour or More after water commenced to flow from the filter. . . 81 Table No. 10. Summary of the Average Percentages given in tables Nos. 6, 7 and 8, the Samples of Filtered Water were collected Thirty Minutes or Less after water commenced to flow from the filter 83 Tables for making Comparisons, relating to the Experimental Morison Mechanical Filter. Tables Nos. 11 and 15. The number of times that Percentages of More than Two Per cent., of the Applied Water Bacteria, Appeared in the Filtered Water. Also the Percentages that the number of times are of the Total Number of Results obtained, (pages 85 and 90). 85 Tables Nos. 12, 14, 16 and 18. The number of times that Percentages of the Applied Water Bacteria Removed, which were used in work- ing up the Average Percentages given in tables Nos. 9 and 10, were One Per cent, and More Less than the Average Per cent. Removed. Also the Percentages that the number of times are of the Total Num- ber of Results obtained (pnges 86, 88, 91 and 93). 86 Tables Nos. 13 and 17. The number of times that Percentages of the Applied Water Bacteria Removed, which were used in working up the Average Percentages given in tables Nos. 9 and 10, were More than Two Per cent. Less than the Average Per cent. Removed. Also the Percentages that the number of times are of the Total Number of Results obtained (pages 87 and 92). 87 GENERAL CONTENTS. . V Table No. 19. Percentages of Applied Bacillus Prodigiosiis Removed from the water by filtration, the Number that were found in the Applied and Filtered Water, and the length of time that they were grown 95 Table No. 20. Chemical Analyses of Applied and Filtered Water 105 Table No. 20. concluded. Special Analysis of a Sample of Pawtuxet River Water giving Quantitative Constituents and Compounds 107 Table No. 21. Percentages of Color Removed from the water by filtra- tion, and the Color of the Applied and Filtered Water 108 Table No. 22. For making Comparisons, computed from data derived from the Report of the State Board of Health of Massachusetts for the year 1892, relating to the filtration of water through Experi- mental Filters at the Experiment Station of the State Board of Health of Massachusetts at Lawrence, Massachusetts. Giving Rates of Filtration, Percentages of Removal, The number of times that Percentages of One Per cent, and More, of the Applied Water Bacteria, Appeared in the Filtered Water of the different fil- ters, the number of times that the Percentages of Applied Water Bacteria Removed were One Per cent, and More Less than the Aver- age Per cent. Removed, and the Percentages that the number of times are of the Total Number of Results obtained. Also the Per- centages that the number of times that More than Two Per cent, of the Applied Water Bacteria Appeared in the Filtered Water, are of the Total Number of Results obtained, and the Percentages that the number of times, that the Percentages of the Applied Water Bacteria Removed that were More than Two Per cent. Less than the Average Per cent. Removed, are of the Total Number of Results obtained 114 CONCLUSIONS 118 Filter-bed Steamed and Boiled 119 Experiments when the Temperature of the Applied Water was artifi- cially raised 119 Foreign Matter in Filter and Filter-bed 119 Effective Cleansing of the Filter and Filter-bed with Caustic Soda 120 Higher Bacterial Percentage of Removal after Cleansing Filter and Filter-bed with Caustic Soda 120 Small quantity of Suspended Matter in Applied Water appeared to be beneficial 120 Experiments upon which the Efficiency of the Filter for Removing Bacteria is based 121 Estimate of the Cost of Operating, includes the Cost of Cleansing twice a year with Caustic Soda 121 Bacteriological Percentages of Removal considered were worked out from End Growths 121 Basic Sulphate of Alumina, the Chemical best adapted for the Puri- fication of Pawtuxet River Water 122 Quantity of Basic Sulphate of Alumina Required 122 VI GENfiRAL CONTENTS. None of the Applied Basic Sulphate of Alumina in its original state, present in the Filtered Water 122 Rate in Gallons per Acre, per 24 hours, that could be efficiently fil- tered, and average rate during experiments 123 Recommended rate of filtration upon which capacity should be based. 123 Bacteriological and Chemical purification of the water 123 Average Bacteriological Percentage of Removal 124 Comparison of Bacteriological Results obtained with the Morison Me- chanical Filter, with those obtained by Natural Filtration, with Ex- perimental Filters at Lawrence, Massachusetts, .(pages 124 and 126). 124 Efficiency of a filter for removing bacteria should not be entirely based upon the Average Results, but the Worst Results should be duly considered 125 Temperature of the Applied Water in December and January -128 Possibility that a cheaper chemical than Caustic Soda could be used in cleansing the filter, in connection with steam 121) Application of Bacillus Prodigiosus to the Applied Water 131 Average Percentage of Removal of Bacillus Prodigiosus ... . 131 Application of Cruikshank's Bacillus to the Applied Water 132 Reduction of Albuminoid Ammonia by Filtration 133 Reduction of Ready-formed Ammonia by Filtration 133 Sulphur trioxide (SO 3 ), in Pawtuxet River Water before and after adding Sulphate of Alumina, and in other waters 133 Filtered Water and Boilers 135 Color of the Applied Water Removed by Filtration 135 Filter-bed can be thoroughly washed 137 Average Time required for washing 137 Quantity of water required for Washing filter-bed 137 Quantity of water necessary to Waste after washing filter-bed 137 Time that Filter will run between washings 137 Condition of the Water in the Pawtuxet River during the experiments. 138 Effective Stability of the Quartz and Supplementary precipitate bed. . 138 Range of the Working Head of the filter 141 Results equally good under all heads 141 Number of Bacteria in samples of filter-bed 141 Number of Bacteria contained in a sample of Eflluent Wash-water 142 Loss of Head, due to the water flowing through the filter 142 Estimated Cost of Operating, per 1,000,000 gallons, a Morison Me- chanical Filter Plant 142 REMOVAL OF WATER BACTERIA BY SUBSIDENCE AND FLOW 142 FINIS 143 APPENDIX 145 Report of Professor Thomas M. Drown, upon the analysis of a sample of Pawtuxet River Water, before and after adding one-half () grain of Sulphate of Alumina 146 Letters from the Hartford Steam Boiler Inspection and Insurance Co., relating to boilers 149 GENERAL CONTENTS. vii Letter from Dr. C. V. Chapin, giving information relative to Me- chanical Filtration, obtained by personal inquiries, inspection and correspondence 152 Extracts from two papers published in the Transactions of the Ameri- can Society of Civil Engineers, relative to the use of Alum in the purification of water 156 Extracts from an article, published in the Chemical News, relative to experiments with Alum Baking Powders, etc., etc 157 Letter from Professor C. A. Doremus, relative to the action of puri- fied waters upon boiler scale 159 Letter from the Treasurer of the Providence Dyeing, Bleaching and Calendering Co., relative to experience with filtered water in boilers and wrought iron pipes 160 Table A. The number of grains, per gallon, of "Alumina" and " Sulphuric Acid," which are contained in 146 Mineral Springs of the United States 161 Table B. The number of grains, per gallon, of " Alumina " and " Sul- phuric Acid," which are contained in some Natural Waters in Massa- chusetts 171 Table C. The Number of Times during Fifteen Winters, that Periods occurred of One day and More, when the Daily Mean Temperature was 32 and Less at Providence, R. 1 1 72 Table D. Normal Mean January Temperature of a number of Euro- pean cities and at Providence, R. I 173 Table E. The Number of Times and the Number of Days in each Period, during each Winter from 1879 to 1893, that the Hope Reser- voir of the Providence Water Works was Frozen Over. Also the Date that the Reservoir was Frozen Over the First Time during each Winter, and the Last Time that Ice was visible, and the Total Num- ber of Days that the Daily Mean Temperature of the air was 32 and Less 174 Estimates of the Cost of Mechanical Filtration 175 Estimates of the Cost of Natural Filtration 178 Summary of the Estimates of cost, of Mechanical and Natural Filtra- tion.. . 181 REPORT OF THE RESULTS OBTAINED WITH EXPERIMENTAL FILTERS AT THE PETTACONSET PUMPING STATION OF THE PROVIDENCE WATER WORKS. BY EDMUND B. WESTON, C.E., ASSISTANT ENGINEER IN CHANGE OF WATER DEPARTMENT. CITY ENGINEER'S OFFICE, WATER DEPARTMENT. PROVIDENCE, R. I., March 12, 1894. J/r. J. Herbert Shedd, City Engineer. DEAR SIR: As directed by you, I commenced the experimental filtration work in the Cornish Engine House at Pettaconset Pump- ing Station in February, 1893. The experimental niters, having been set up, were started about March 27, and the work was continued, with the exception of a brief interval in September, until January 30, 1894. Two Experimental Filters, N"os. 1 and 2, built according to your design, and an Experimental Morison Mechanical Filter, were used during the course of the w T ork. Another Experimental Me- chanical Filter was also set up, at the expense of the owners of the same and run for several months, but as the results obtained with this filter were not satisfactory, it will not again be mentioned in this report. Nos. 1 and 2 filters were run for about seven months as natural and mechanical filters, at rates of flow of about 2,000,000, 5,000,000 and 30,000,000 gallons per acre per 24 hours. The work with these filters was then discontinued. The term Natural Filtration, is used in this report to designate the filtration of water through a bed of sand or quartz, when there has not been any foreign substance added to the Applied Water, and the term Mechanical Filtration, is used to designate the filtra- tion of water through a bed of sand or quartz, when some foreign substance, such as Basic Sulphate of Alumina, has been added to the Applied Water. 2 FILTRATION EXPERIMENTS. A sketch representing Filters Nos. 1 and 2, is shown in Cut No. 1. The arrangement of the interior of each of the Filters Nos. 1 and 2, is as follows : Upon the bottom of the filter a bed of cement about six (6) inches deep was laid. Several rows of bricks, set on edge, upon the cement, about six (0) inches apart supported a floor of bricks laid flatwise. The bricks of the floor were cut so as not to leave any openings of more than one-sixteenth (?-%) of an inch wide in the joints between the bricks or at the sides of the filter. The filter-bed consisted of three (3) inches of " pea gravel," which was placed upon the brick floor, a layer of coarse sand one (1) inch thick, which was laid upon the top of the l( pea gravel," and upon this coarse sand the filtering medium proper was placed, which was composed of a layer of " fine sand," of uniform quality, one (1) foot and eight (8) inches deep. During the experiments sev- eral kinds of " fine sand " were used at different times in Filter No. 1 as the filtering medium and one kind during the entire time in Filter No. 2, the Effective Size and Uniformity Coefficient of which, are given in table No. 1. A representation of the Experimental Morison Mechanical Filter, which is described in detail in that portion of the report which describes the experiments made with this filter, is shown in Cut No. 2. At the end of the runs of each of the Filters, Nos. 1 and 2, the filter-bed was either washed, or about one-half (|~) of an inch of the top of the filtering medium scraped off. When each filter-bed was washed a one -inch hose was con- nected to the discharge-pipe at A. This hose supplied the water used in washing, which was forced up through the brick floor and filter-bed under pressure, and overflowed through the six -inch branch at J5, the cap, to which the inlet-pipe C is connected, having been removed. The results that were obtained with Filters Nos. 1 and 2, and the chemicals that were used when they were run as mechanical filters are given in table No. 1. In the same table are given the results that were obtained with the Experimental Morison Mechanical Filter during the time that Filters Nos. 1 and 2 were in service. This table is intended for comparison only, as the bacterial colo- nies, from which the percentages contained in the table were de- termined, were only cultivated from 42 to 62 hours, and " Fifteen- FILTRATION EXPERIMENTS. CutJYa.l. 4 FILTRATION EXPERIMENTS. per-cent Gelatin " was used the greater part of the time as the cultivating medium instead of " Ten-per-cent Gelatin," conse- quently, it is quite likely that the percentages given in the table are slightly unreliable. The methods followed in regard to the bacteriological work are described in detail under the head of Bacteriological Work in that portion of the report which de- scribes the experiments that were made with the Experimental Morison Mechanical Filter. Table No. 1 practically describes itself, and it contains the only information which I shall hereafter mention in regard to Filters Nos. 1 and 2, owing to the very limited time at my disposal for the preparation of this report. When Alumina or Alumina and " Free Flow," are mentioned in the table, in connection with the niters, it signifies that Basic Sulphate of Alumina and " Free Flow,'' were added to the Applied Water in the same manner as will be mentioned later on in detail in the description of the Experimental Morison Mechanical Filter. When Natural Filtration is mentioned in the table it signifies that the filters were run as natural filters. The "Effective Size" and the "Uniformity Coefficient" men- tioned in the table, were determined by the methods followed at the Experiment Station of the Massachusetts State Board of Health at Lawrence, Massachusetts. The " Effective Size " of the filter material (diameter in milli- meters). This size is such that 10 per cent, by weight of the ma- terial is of smaller grains, and 90 per cent, is of larger grains than the size given. The " Uniformity Coefficient " is the ratio A to B when the values of A and B are such that 60 per cent, b} 7 weight of the material is finer than A and 10 per cent, finer than B. FILTRATION EXPERIMENTS. S 8 ^ ,0 <5o .i- g e -to e 5 J2 t o e g S o s 1 1 ls|1 I" %"S-5.1-So i ^ S 8 =18 o a a^ GO ^ O Z_, frfr r* nd Grain Started 3,110,0 S<* * 'I ^ 2MS fl ^| a o-g.s P.IS S M ^ O CO CO CO 'o OS 00 O CO g ^%-l O I CD j CD FILTRATION EXPERIMENTS. ICAL FILTER. Gallons of Water Filtered per Acre, per 24 Hours. i Quartz Grains dium 0.59 mm. it 1.5. ural Filtration. 128,000,000 o" o co" Ci 118,000,000 127,000,000 O O CO ft A a 3 W -^ TJ. 03-d rH o CO 3 g^s-^l^ o^? ^ pd Ci JO q co a g^s S 1 J P-i PQ p3 ^s^ 4 j^ s * "St: .El ^ Oi CO CO JO ^1 o a'S^fl^-l Hl|s CO rH rH Ci CO t^ CM JO o 3 S 1 s^ S'sSs CM d O o O H h< CM CO ^ Ci ^ JO rH JO JO Ci 'S e_i IH i o o> PJ |i|s O O O 0, 0^ o -^ o cT JO o CO o o" ! oo o" ; CO o" s o " o" o 33 s? 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CO rH ' E CO (^ GO i-H Cd Ci JO 10 CM CO OO 00 TH 00 C^l b- co CO 1O CO Ci CO CM j-1 CO *o Ci Ci o ci GO Ci CM rH rH CM rH "- ' 1-1 CO CO rH CM CM CM CO ' ' ' Ci oc - rH * ** ~* * ^ ^ ^ ~ * ~ ^ o to t>T co" cT o^ i-T CM" CO T^i 10" CO" *T co" cT T: FILTRATION EXPERIMENTS. 1 si -E 8 o o O O O O 8 8 I ill : | rH | T-H 1 co~ " C^ CD^ co" co" rH o 8 co" 1 co g ^ rH rH rH rH rH T 1 a ^ rrj cS-d O CO CO Oi CO b- CO O 8 Mil CO O g g o 01 Oi C^ Oi Oi ** c3 rd . 1C ^ CO CO O T-l 3 faS-2 c? > rH ""r-^ s r^H - S 1 8 o o 8 o *" j P O " 3 ^"* "^ o CO CM ^ ^ ^c$ ^ CM o CO o . si Ots ft CD rH rH T-H CM rH c i p4 fc P" M ^ rrj c3Ti CO CO ^ CO O B .2 _ g > : CO . g ^ >^ C5 Oi Ol 'C^ 1 O rH S ^"w^ mi : " o T-H CM T-H 01 CO & ; ; \ \ oll S "re '+2 ^ 1 8 ps g : o (^> * * * Q r^ "<5 ^^ CM CM ,4 || || |s ^ CO T-H r ^- CO rH 6 ^ ft E^ 1 ^ l g-2 f S sl -* CM 00 T-H EH g^^-2 o ^ ^ . ^ T-H CO o hq ^ > g ** : G5 1 cs . 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CM Cl 01 P3 >H ^ ej ^ CO 10 o 01 CO CO 1-1 ^-^ a t* rH CM rH CO CM CO 1 1 rH CO ^o z* M g 'd^.ce^ CM CM 1O o CM ^ CM CO H ^^S-S o3 ** CO OS O 10 CO CO -fl g ri^ii C5 o OS o OS 1 1 is 10 CM o t- 10 10 10 rH CO CM CO CO I1' S H * rH CO rH , L| B || OS GO rH OS 10 CO rH CO CO OS rH rH 10 -H 10 CM CO 05 CM CO ; ^ 1 - CO CM 10 ^ CO o o GO CO . ( ?5 pq ^5^ rH CO OS w s* ^ ^ ^ ^ M EH rH O 10 tr> CO o rH rH CM CO ^ CM CM CM CM CM CO CO 08 fl r-i FILTRATION EXPERIMENTS. 11 : o^ o rH Tl j ; ' 1 o o ill ' ^ co" v Ol 148,000,000 o o o" 01 rH ^ a 119,000,000 Free Flow." CM rH o 8 : 8 t>T rH rH CO - rjn a 10 'd OS 10 OS a o OS o % OCS CO OS os d rH c rH g * CO ; \ \ 1 b- CO i CO ^ 10 CO : of rH o 8 o 8 o 8 rH CO of rH of o CO i H o Oil of 01 CO of GO T i of GO OS of O 1O CO ^ of 1 GO rH of OS 10 co CO CO t-^ OS OS Ol ts. GO GO O GO OS OS OS OS OS OS OS OS OS rH CO OS rH o OS OS OS 10 o o rH 10 10 oq . CO ! rH CO 1 1 o 10 Ol O ** 01 CO o rH GO Ol 1 O CO of o o" OS rH o o" 01 OS r I 2,200,000 O i o" OS rH o o" OS rH a | 1 co" rH co" 0^ co" : 8 rH CO CO 10 GO ^ OS t^ ^^ ^H 10 CO OS CO OS OS OS OS OS OS OS OS OS OS 1 OS OS 00 OS OS CO GO GXJ Ol 00 rH CO ^ 01 ; GO 01 2 s CO Ti OS 10 : 3 GO" 10 OS 10 o" o 10 os~ rH 10 GO" rH o : GO" O CO ^-HX 00 rH of (^) G\\ o co *o co 10 01 GO o" OS co" 10 rH 0, rH CO OS ; : GO rH 10 CO t^ CO OS O rH Oq CO HH 10 CO t> GO OS 12 FILTRATION EXPERIMENTS. O O O 1 _, Q < a|f| O I ; '. ; ; s o 8 1 O o H-3 ^ 4> 0) rH CO o CM O g a | s CO rH CM rH CM rH CO rH 1 Mill OS* . | CO OS O5 8 GO OS rH 02 f-c 03 73 . S 'C "^ ^ CO o : ; ; ; ; rH 00 GO rH * o 11% oj>g'| . o 1 o 8 O o 8 O O O o O o o O O O ^ ^ *** CO OS CM CO rH CM 3 f-H f_ 5 o o CM *o CO t>. 00 0* o~i ft CM CM rH rH CM CO - CM CM rH 1 1 o ft K -^ 73 cJ-d ^ GO (^ OS CO CM 10 ^ ** 05 05 OS OS O rH 05 05 GO O5 CO 05 CO 05 05 OS OS 1 1 Is 10 CO t> CO CO CM rH CO rH CO CM o C5 CO O t- i H I1"II * rH rH CM g ^ o o o o 8 8 8 O o Q 1^ 0" r- o (^) (^t O o (^) o (^) |!| HH CO d 1 CO O o o rH CO cT CO o CM CM CO <& CM GO CO o O 3|&jj CO CM CM CM CM CM CM CM CM CM M ^ rrj^.g'g os ^ O5 05 rH ^ GO ^ OS FH ^.^s-2 5 ^ GO O5 OS O 05 GO OS OS OS OS lj I^1I OS OS o rH OS OS os 05 OS OS lil CO rH OS II rH CO rH OS CM OS rH rH rH CM j i klsll | 00 GO CM CM 00 GO CM CO O CO O O OS OS ' e8 ^^ CO CM rH O rH CM *o CO CM < PQ "^ rH ^ CM CO OS g GO 3 ^* ** V. V. ^* "* *"* ^* ^* fi CM CM CM CO CM CM CM CO CM CM GO OS CM O co 0) 3 FILTRATION EXPERIMENTS. 13 | 8 O o o o o 8 O 8 g O o o o 8 8 R V R 8- 8 ^ g g 8 o o o o . O OS CO CM CM r | GO CM fc iO ^ CM rH GO iO * * | * rH rH CO o 8 O 8 8 o O 8 o 8 ~S'-3 O o CO CO o 8 : O CM O CO ^5 8 CO OS t^ CO CM CM TH 'a> ^ CM CM rH rH CM CM TH CM CM rH a5 ' c5~ |^ j^ CO TH 10 rH CO 10 O O ^ CO CM 5^ CO GO OS o OS OS OS CO OS OS OS g as CO OS 10 as ^ . *o 10 rH TH CM 3 CO CO OS CO 10 rH CO CM ^H Washed Started 985 8 O o o o 1 O 8 O o o. CM 8 : CO CM CO OS g O CM CO o o: 10 CM l>- Tl CO CO CO CO rH 71 CM CM rH rH 11 CO Tl rH rH GO O rH TH CO ,_, CO TH iO GO CM O GO OS 10 OS CO OS OS OS CO OS OS as as o a: CO as GO as OS as 5 CM rH ', OS CO rH CO CO rH CO rH TH TH CM Tl rH O rH 10 HH t^ " rH ! 10 O O OS CO OS ! r- 1 CO O CO GO CM CQ GO as OS 10 CO TH ' CM CM rH rH CO GO rH S S v* ~ N \* - s " 3 ^J ~ r I CM CO -H CO t> co as o rH CM CO TH 10 3 14 FILTRATION EXPERIMENTS. <^> ^ (^ w oIL'i o 8 o O o 8 E jill . : 1 8 8 8 8 : | 8 h-) eg o? 5 r _^ P4 "O O 10 CM CO *o T 1^ o l ft ! C ' I rH rH o CM rH CM rH rH rH CM rH CO rH Jj -g gn.g'g ^ -3 CO 05 GO S !i|l| o a 05 * 8 8 8 05 CO O5 O5 O ^Mpi* .S o tH OS ^ . L^ 1 CM CM ^ ^ ^ rH 1 1 5 "ctH ^ e cB-2 CM ^ ^H o gin* - 00 O5 o rH CM CO HH in rH rH rH rH CM CM CM 05 CM FILTRATION EXPERIMENTS. 15 g 8 8^5 (^) o g 8 g g g o O 8 O 8 1 1 : o o 8 8 CM" CO ^ ^ CO O CM r 1 CM rH CM CO CO CM CM rH CO " rH CO rH o o q ci ci O o o OO OS ; rH c; o OS o o rH O rH "* o 10 C5 r i rH GO rH rH *^ ; o ^ . o o O o o o (^) o o o t5 s o o o o . o ^ o o o o 8 10 . co 2 g GO CO . i>T .g.2 GO ^ co" CM ^ ill ^ Ij CM CO CO CM HH co ' CO g ^ CD rH CO* '^t^ CM' ^.13 ' CM OO OS GO ^ . O -d-SjJ oo 3 . OS os OS OS OS tt^J 2^; CO I O OS oo ^ CM CO S| =1 CO T . | rH~ rH rH rH rH rH ' 1 o 5"- o o "2 S 8 - 8 I| fj .2 o O O ^ o 8 p_O 1 b- ^ 0" & *| fljlll !| S i o ^ > o" ^ 2, en &* ** ll : CC CO ^ S l| C) (T) w -eg ^S ^ || s l| I 1 g CO GO CM Hi" CM ll g'l **! CO ^ .13 o 72 cS SZ5 GO ^"g^-j O O ^^ ?H^ 8 i> GO *" . -3 rH M W C3 ^ |2 a 5 'o o pp 'S 'g.S tfl W .S ^ '3 r-CO t2 ^^^ TjS 1 O iO rrt 3 CO ^^ 10 xa - 5 ^ ^ *O Cu P Ci CQ t> -g l> ^ S X j3 CO CO CO CO ^ || ; ^H ^ti SKI : 1 CO Os" !2 5 ^1 ! 10 CM b- ^ CM CM 10 ^ CO HH HH -j-H ~^ l^ OO f^ 10 ^ CO IO -rfl t> OS CM CM H^l . rH r 1 OO iO CO rH rH CO' b- 10 CO ' : : : * " ' CO rH 5 ^ ^ - - ^J ^ ^J - CD" uj- oo" oT rH rH CM" co" rs ^ CD" CM CM CM CM CO CO CO 3 16 FILTRATION EXPERIMENTS. EH J ,B | 1 O 8 8 8 O | o fe fill 8 o o O O 8 : o" o 8 10 c 1C i-q "efl S* 10" iO CO ,_," 10" if GO r-H rH <5 o Ots ftfe GO GO T I CO CO GO Gl Gl h- 1 ^ ft W g ^^-S^ i | ^ CO HH t^ co o pl^il OS O o rH 8 rH OS OS : OS 00 O! o 02 S 'S^ ^H TH O IO CO TH rH >0 O ll"|l ' sL-i o o o 8 8 8 o ^^ 0,2 o o Q P-H ^ '^ o o o O c ^ !-i t, ^ TH CO CO *o 10 CO cc . GO CO o O * Q G? ^ HH a pP|J CO OS C5 CO . *fj 'S ^ s CO CO CO Gl CO GO ; CO CO o oo fS' s i^ " Cl rH rH GO -slafl g I . c 8 o o -gg 1 S^H o 0' o o > X ^ 8 8 1^ " '. o ^ ^ a3 ^^ OS ^fe o 10 CO fr ' "c S c^ TH 6 ri G? ^ CO CO ll i CO CO ^ 'f & .2^^ 0,2 <0 -~ FILTER Hill q t> CO CO' ci o CO CO* Q^ 0^ CO CO CO CO* OS CO o 16.2 Repackec Size of San I s ! ^ o P j> -g *gj o CO o- 10 00 r X ! O 10 CO CO ^-rt . & i- S = o-g.S^"S r 1 > ^ GO rH CO fe o -i ^ m s^ 02 rH s ! g .* f rH ^ 10 10 Gl IO -~ ^ ^ &5 .2 s CO O CO ^) rH CO rH f 3 "o -g .S "ftte CO CO CO OS CO i ? M -t^ r I ^ rH CO TH CO : * CO rH * * " ** ~* ^ " ** M 1 r>T 00 cT cT rH G^ CO*" TjT 10 fi GO bC pq ", FILTRATION EXPERIMENTS. 17 1 x O 8 O g o O i o o CO g >o o ] | ! ^ ^^ crT OS 00 m 'GO O5 - r^ rH CM CM CM CM 00 CO CO CM cri ; ~. ; ; s*. rH w GO cs ; 1 ' -H rH rH ^ -h rH ' | j 1 o o o 8 8 o o ^ ' f ^ cd o o CM :c CM ^ GO L^ ^ 5 CM .""^ pX o ^""^ i i ^ ro ^^ / * C3 CO* O o oo ~' ^^* IS o CO CM CO co ! to Cl - S CO 'O GO : 1 CO c^ I s 8 o ii g 8 o 8 fe ti. i 5 o f f | : g o g g 1> i t> O :1 |8 8 CO 00 o o f- pq ' CO ^ g 10 10 , , CO r^j ^ jj co' (^ rH on fe CO ^ rH (> r*) CO CM 70 si ! CO CO CM CM sl| ^ CO cs iO CO b- ^^^ rH ."Sn^ "* ^H CO _ "H ^ .2^ 1 o CO . ^-2^ CO -P c o CM rrs cs ^s rrj -^ Cd o o "^ Tj ^ " o ^J ^ -^ t> r'n K~ ~ 22CO ^ ' .Sec ri r- -~ .s ^ ^ ^H " ~ ^H o 00 -H ^ 1 OS . 1 1 cT" S I^ ? JO rH CM rH CM O l q ; to 1/2 5 O CO " - 1 CM O CO os ^ CM ^ cs o ^o (7"S g o 3 *> CO o o r - l||? 2 i ^ ill CM ||o o 00 i i CO o |* i ^ oT|^ o CO '111 1 81 1 to s C7i ^ jj gj ~ r H to os 1^ 00 CO Cl T 11 ^^ CM 1 ^|||| s ^|1 OS cz ''^'fl 00 "S s * CO : ||1 CO 00 OS ^3 rf cS s ft ^ -<"^ 1 BooJ Mcc fl pqceg pqCCg o3 ^^ 00 | to J I y-j x 1 o 2 i3 _ ^et-i O * ^ e 5j CO '^ c 3 CO c -5 t>. "^ eg <5 X ITS? ^^ ^ : * S O "^rH CX C3 CM to CO CM os 1 ! >o GO CO 1 pq -^ T 1 CO 1 1 rH CO : ' j H 00 r- 1 V* ^J JJ - s* ^J i o" CO T r CO rH rf co~ 4 f &b "ft 5 03 rf) FILTRATION EXPERIMENTS. 19 o o 0^ o^ CM~ I CM I 1 O c^ CM" o 0^ co" CM j j ' S C5 o C5 O5 (? o ... T3 ... Ci 05 o 05 * w> * * " rH S ... T 1 L " 05 CO 5 : : : : 1 cT o o o^ o o o O ^H' o o" | CO o CO o 10 o '0 CO 8 *c . o rH o - ^^ CO ^ 4J CM CO CO CO co jg^ 2 CO ,4 rH CO H -"S ^ CO ,__! CO CO t>* O5 T3 . . ... 05 05 O5 05 /--^ r s*- . ... w^ ** CM GO O5 o o 3 rH O5 : CM ^ 3 : : ; : 8 8 s ^ o % ~ o 8 & Is . C^) jj c^> O> c^ CO O ^ fe o & | * ^ s ^ 8 1 * > o V S > ^ 8 8 $ : : O^ QC^ ^ ^ . CO O > fo o> 00 s|s CM CO CO |g CO H+a.W i S || o rjH S-d' t> ^ CO S-g^ CO GO -^ ^ 10 CO tj S 10* . ^^'g ^5 CO ^-2^ t^I CO CO : Il ro O5 M cc 5 GO ^ c^ ^ Woo g 00 ^ l| 1 1j S 05 -S -2 CM J ^ 1 . rS ^ 1O 3 3 ^ o rH s ,oJ CM S 3 CO j^ t^ 10 J ' CM CO 10 o rH ^ 10 CO CM CM - ^o CM -^ o rH CO ^ L^ TjH CO O . rH ^ * CM rH ' rH CO \ : : : ' : : : : O5 CO ~ 3 i! ^ ^ ^ ^ ^ ^ s jj oo 20 FILTRATION EXPERIMENTS. I ! Mi i o o o o s | ^g 5 EH O tl O S s 0_ S s Q 1;!' ^ 00^ ocT CO X FILTRATION EXPERIMENTS. 21 o g 1 o^ o s 1 o" CD" . cT -. o ~, o o^ ~' o co" o^ 01 rH CO rH cxT rH CO 1 1 h o CO s r' CO 8 o C5 Oi OS 1 J r- | CO o ^ t> CO a 1 .2 IQ o o^ g o 0^ 1 g q hg I a o o o ; g ^ T3 CO to co^ 30^ **S CM ^ c ~ ^^ o" rH ' ' s^^ co" -2 o CO CO CO CO 77 si co s 1 CM rH to :? 11 o rU g CO CO CO t ' ^ CO - Ci 35 <1) CO +3 03 g CO t to (^ CO ' ^^ 01 (D T-H CM , rH CO * II to 1 GO" rH ^ CO g o 1 , 8 o> ~ O o | = o ^ s o ^ ^o o" o" : ! .11 81 | c 1 ^ >> J3 o" o o, ^ s p o p f-J rH r _ 1 t> ^ CD ^"^ CO Si fe Hi ^ ^ Cw -*-> o -5 s CO CO CO jg|j$ CO jg-2 co 5? g ?? JES ^s^ K FH IS^ co CO ?! 3 CO S-^^ l^ H o sg ^ +* [^ CO CO t? Pi . s ^ S3* CO lls ll |i O5 ^ .a il .s .s o -g 1 CO Oi .3 to " 'S S 0,1 1 * CO CO ! ^ ^3 to rH q ! ^ T^jH s CO rH ^ s '""' r ~ l ^~ ~ co" rH t>r rH co" 10 'So CO co b- ! to CO 00 01 CO o CO o c<3 o Oi , CO CO o TJ^ ^2 co" ~~" co" co" o r rH IH to CO o ' * s number rs o" ^ ^ r. ^ s 01 CO W c V^ {^ ^ -^ Loss of Head in feet, due to the flow of the water through the filter-bed and dis- charge - pipe, at the commencement of each run. nary. The water grad 5and Grains 0.81 mm. U 0.0156 1 with New Sand. Effec formity coefficient 2.1 0.3646 ied Bed with Filtered 0.1667 ,t a constant height of pe was gradually lower with New Sand. Effec formity coefficient 2.0 ^ a g 33 j 1 1 ^ 2 8 1S pS Ctf S o "Pn" 4 "* ^4-2 Q* t- *ir^ *r^ 4J ciS cS & p ( q ^ . ft O | CO M CO c^ -* T-H r^j 1 1 CD o 1 o go | 02 01 OQ 111 S ^H M -H o }?l w - ^a 24 FILTRATION EXPERIMENTS. w g s s g ^. til T 1 !> Ci CM 05 ^ CO iff CO t>- r 1 rS^ rH & CO CO co ^ CO 3 g^itlllll g s C P o o |-. ^ ^ CD O^ O - g T3 d r =- S^ r*- tj rr^ ^ H S f^l -^ -*-- p *"^ ONTINUED. FILTER No. 1 ~J ^ S-i S 0> 0! jtive Size of the Sa Natural Filtrati 4.20 . Alumina and " S E t^ "g 01 l^- SO (S 10" s* ^ - J2 CO 10 jtive Si/e of the Sa lumina and "Free 5.01 ^r 2^ |o | ct ^ ^ ^ ^Tr^ >J Q W -i-3 ^ CD C 1 . r^ Q _j ^ C J^ w r 1 C3 JH ^ C t5 ^ ' *.2 ^ w d -lifsP li o i < C1 S o 5 p CO 11 ^ H ^o O S.-& ^ a ^ o ^ o 0) S H K o II ' _ 9 Soil |i ^^ w 1 1 H sa "? 'C 1 S ll ^ 8 S "i 2 &5 2 5 o ^ r^3 Cl S^'S HH '^j O O 0' ^ .f ^ r c O -^ "S -C! <71 Ol (71 rtf CM K I 1 * '2 M O o CO ( ^ ) ll'l S 1 111 S g d s . s ; o CO ; s o a 00 V. ~ -* a 8 r-T co" 10" 0^ *N o 5 bb bO fcX) bJD bi) 1 - rH ^7) O OO iO CO rH CM T 1 r I T-H Cl 0000 8 8 o ^S 1 1 1 1 i 1 o" 1 . o^ | o^ | cT | BE ^o S ' O S ' . ".; CO P- CO ^ CO coo S S S O S- " O 52- " O -21 '- O 3 CO ^ CO ^ CO ^ CO ^ ^o _o -d 2 c ft CO ti 00 cS iO cs OJ 03 O G CO* s CO "ft 1 1 3 03 00 > 10 > co p -^ g T*J w o ^ o ,- o ^ *O ^ CO t> < ^* ] t> CO to p^ *O ^ "^^ Q3 *^ ' ^3 d _- d A o" 5 pq III PQ PQ PQ g 1 111 O r?-j 01 10 1 1 1 111 ^ ^ O >0 10 '0 10 O O O O i CO 00 2 S* V* V* U i-4 i 3D" ci en c. CO O CO O " 90 . . J3 ^ ^ '"C ^ "^ <4H O CM r-i i i T 1 rH ^IjlllfJ O O O ^S^ 5 j +j ^^i-t - O 6JD 8O> os 03- o ^^^ g '_^ 5 M 'S E ^> ^0 O o O o ^8 ^f-i^Sc^-^^^^^ (^> ^ f^) _^ ^D o" O 5 cT ^*^ ^r if P til IB, SL i s, i ;. 53 ~. o ;: - ^ CO ^ CO ^ g S g S ^ o ^ a - - r O o " O *" O 52- CO ^ CO ^ CO rH +f ^ ^ ^ Q^"trf ^ ) Q o o o ES*^ o5 5 s s s s s T: ?J t- 03 03 OT I I I 1 1 o J2 53 <-> 3 ^ pCt'ZH OS 'H *fl 's cs Oi cS *O> cS co a co i oo 5 fctsfl'o ^ 33 "^ 03 ^ ci .S co .S co .S s a s ^ o3 ^ e8 "^ co .S co .So a a E |2lsil -35,5 -< ^ "< =3 S O * > OJ O) CO t* CO t> 00 'g'S-S^ g'Oj.H P5 o jg co g co S ^ S co w^l^'ftgo ^ O ^ O f< ,=j O ^ O Stp,is>a "I 1 I . '1 '1 M *^ C> C^ O 'rt *rf 'rt rrt r-^ 1 .^-l O-4J O PQ PP W PQ pQ as 'O 'C Ti J! J s CO W 02 o d) "I 1 'S.5 03 5 > fe > S 43 S^ 5 O 000 .f *o ~ o ** ** o 10 o 3 lli o o CM" Sll i s 1 1 CO C5 a oo ^ il ^J s T 1 o GO" ^-T ^"T -rjT |>T T I -H % 1 CM 4-J -4-J ^ ^ ^ I ^H ' /3 CO C/2 FILTRATION EXPERIMENTS. - I II ^ C ? t r > ^ r ll S 5 ^^ {^ " > !_ r > i O 11 >" r > i 1 1 i! i ' > i^ >^ o 0" x f o 2*. - O - i -- -.J o I c^> ^ o" ^ :, '. CT~^ ^ o co _c CO CO 1 CO ^o CO _o CO S S s 1 i u 1 I d 'C d d d ^ c a c - ^> a *_^. cS H c^ ^ J S3 o C!3 T I a rH aj O3 S CM -j jjjY"3 a 05 eg C^l ,_5 fl (^ ,-H _G ''M* c rH CM" S ' S S '| < < ^ _^ S O M -H ^ 0) o S -H S o 2 CO S iO S 10 s ^ ,d O o ,3 ' ^2 o ,j O O ' '% $ ^ '^ 1 , . rg ^ -C r^ T3 13 i PQ w PQ PQ M | T3 d> T3 O 73 0) 1 "8 ^3 S j2 ^a s eS eS aS C3 ^ ^ ^ ^ >o t> o iO 1C t^ uo t> CM' en" o o5 CO Oi 00 1 1 * ** ** ** * oo" cT - ' *s CM TjT 0~ CM CM CO ^j ^j ^ ft o -4-5 ^ * J * <& OJ 00 O O o o 28 FILTRATION EXPERIMENTS. ill |.2.S 1 CO CM CM ifl r-1 * 10 *o CO rH GO 3 bed clogged up. atural Filtration. li . The discharge- is 0.81 mm. Uni- 2,000,000 (1,880,000) i. 11 CO . kept stationary above the filter- icharge-pipe was c5 fj;#sJr l 1 3 |^^ 5^ o> .'5 e o CS^g^ CO ^rK +9 ^ ^ 13 ^S^3 S^_, l|^fl c3 l^H -*-| J 5 OJ+j fcJD > ^ *^ CC 0) t> tx^vi *-* S^d d HI ose in the lity coeffici o rH rt 5 ri^ 4j-o e 0) <&<% 0) J2 O^^ CO 1 &> 3 10 ~-H H! X=t-H ^ o,o*> S^ tS'slb'o S w .sl.slll -0 a'c IIP 1 Sfl c2 "*"* rn fflS O 7- t4_i S-H r^ O ry. The water grad d Grains 0.81 mm. U rH O constant height of a was gradually lower th Same Sand'. Effe< rniity coefficient 2.2, "~ i s o 5 W O Sis 13 6C**-t tjQ Q ^j ^J i^ 2 & 'd O r^ ^ Sf* ^ J-! &JD ^ * S Tj5 ^Jd'ic .1 'l 1 -2 ^Sr-.'^ 3 ^il i& g 1 c 2 'o 1 CO s O5 ^ 1 CO rH *0 S 2 S "S * 88 3 ^ ^ 1-8 FILTRATION EXPERIMENTS. O -hi CO ^t 1 O CO C5 O t>- CO rH rH CO CO 1O O t^ rH rH CO t^ CO CO CO cq CO CO O CO 10 O HH 05 t^ CO rH I- i" o o^ o^_ o^_ o 1 cT 1 cT 1 8 . 1 C- S co _o co i! CO O O o" O o" O o' d" o 1 ll ll 11 li CO CO CO CO CO fl fl fl 09 .2 .2 .2 fe fl -, g g g 5 1 | 111 O T: S fl 2 fl a 03 *s 2 | fe i o ^ 1 5 CO 1 | l> 1 1 ^ 1 HH Sg ^o 5oo 5c^ 5co |f | ^ * ^ * ie averagi <^ ^ "03 "aj 13 r*-( *c3 ^ ._ .. | | | "5 ~ 3 " 1 fc ^ [2; ^ ^ b^ fe 3 fe 1 1 1 ^ ^ 5 aj pq PQ OJ -^ -^ .^ OH P5 PH 1 1 d rH * -c os 1 s I O Tj CO ^3 l>- ^3 CO ,G CO ^ ft ^ GO .- CO S CO TJH S 1 "^ ^O ^d ^O | s 5 .3 S o t/J i 1 i 1 s i ^ CO CO o O O O O >O 10 10 10 o t>- /. * o o* d o o d co* d CO r^s t Ow ^ oo rH - ^ ^ ^ ^ ^ 10*" oT CO*" CO O5 d" rjT t>T 1O GO CO CO f t bb p 1 1 1 I 1 30 FILTRATION EXPERIMENTS. i 1 rH W Sa o o CO . co > -_, C X w _: 2 X S ' | X 7. r .Sg ll 1 s cS 1 " 1 g| s'J 5l 'So Per cent, o color removed. cc co cc o t- co cc 07 co c a co Average colo of Filtered Water. o o ci Average c of Appli Water. M C^ ?Vl 5^ CO " ^ss^ t>- O OD CO 'CO r-lL>.r- 1 i i OOCOrHOOL^?>- Ood -3 _r o * .G IB i Isl OiCOOOOCOQOCMCOCOOOOiO T+* 'T^j c^) GO t^ t> w^ G^ *O t^* ^^ r C^) C^l ^H o o o o o o o o co q q CO QQ^SSSSS-SSSS T I CO GO i-H Cl "^ L^- GO ^ O <3asic Sulphate of Alumina had been added at the rate of one-half (T]-), three-fourths (), and one (1) grain per gallon, and obtained the same results, namely : no traces of the alum tint were detected after the application of the Logwood and Acetic Acid test in any of the samples of water that had been filtered through paper. Several tests were also made with Distilled Water freshly distilled from River Water, to which Sulphate of Alumina had been added at the rate of one-half (|) grain per gallon, and the alum tint was visible both before and after filtration, though of a slightly darker shade in the former. The alum tint was not produced in the Distilled Water owing to FILTRATION EXPERIMENTS. 41 the absence of the constituents from the Distilled Water necessary to decompose the Alumina and form a hydrate, consequently it passed through the filter-paper, in the Distilled Water, in a solu- ble form. While we were in doubt as to the complete decomposition of the applied Alumina (before Dr. Hooker's suggestion, that the alum tint produced by the Logwood and Acetic Acid test in the Filtered Water was due to a finely suspended hydrate instead of Alumina in solution, had been found to be correct), several ex- periments were made with two settling tanks (having a combined area about ten times the area of the filter), in order to ascer- tain, if possible, if a more complete chemical action would take place, if a longer length of time was allowed to elapse before the Applied Water (after the Sulphate of Alumina had been added), reached the filter-bed. During these experiments the Applied Water was first run into a tank (having an area of about sixteen (10) square feet, and a depth of two and twenty-five hundreths (2.25) feet). The Sulphate of Alumina coagulant was dropped into this tank instead of being dropped directly into the filter, and the " Free Flow " put into the filter in the usual way. The water flowed from this tank, through an orifice, located about four (4) inches above its bottom, into a larger tank, situated directly under it (having an area of about thirty-three (33) square feet, and a depth of two and twenty-five hundreths (2.25) feet), and from this latter tank, through a pipe, one and one-quarter (1J) inches in diameter, connected about three (3) inches above its bottom, into the filter. It took the Applied Water, which flowed continually through both tanks, about twenty-two (22) minutes to pass through the first tank and about fifty-three (53) minutes to pass through the second tank. The results obtained, from the experiments that were made with the settling tanks, were not quite as satisfactory, from a bacteriological standpoint, as the results obtained by dropping both the Sulphate of Alumina coagulant and " Free Flow " into the filter, in the usual way, as has already been described, and there was not any diminution in the indications of Alumina in solution in the Filtered Water, so far as could be discovered by applying the Logwood and Acetic Acid test. When the filter was started the water commenced to flow from the outlet-pipe, generally, about five (5) minutes after it was turned on to the filter. A sample of the Filtered Water was always collected one (I) minute after it commenced to flow, and 42 FILTRATION EXPERIMENTS. five samples, one every five (5) minutes for one-half hour, and then hourly during the day and several times during the night. No alum tint was ever visible in the one (1) minute and six (6) minute samples, when the Logwood and Acetic Acid test was applied, either before or after filtration through paper. In all of the other samples, the alum tint was visible before filtration through paper, and in the eleven (11) and sixteen (10) minute samples it was visible after filtration through paper and occa- sionally in the twenty-one (21) minute sample, but it never was detected in any of the samples taken later than twenty-one (21) minutes after the water commenced to flow from the filter. The eleven (11), sixteen (16), twenty-one (21) and twenty-six (2(5) minute samples had generally, before filtration through paper, a darker tint, which grew less as the time increased, than the hourly and night samples. The same may be said of the eleven (11) and six- teen (10) minute samples after filtration through paper, and of the twenty-one (21) minute sample when the alum tint was visible. Great care was taken to have the Logwood decoction prepared properly. It was also necessary to guard against filter-paper that contained traces of aluminum salts. The paper was always tested by applying the Logwood and Acetic Acid test to two samples of freshly Distilled Water, one of which had been filtered through the paper, and one of which had not. The best results are obtained with the Logwood and Acetic Acid test, when it is applied expe- ditiously, and in making the test, in order to aid in detecting the alum tint, it should be applied to a sample of Distilled Water at the same time that it is applied to the samples of Filtered Water. BACTERIOLOGICAL WORK. As I was informed when the filtration work was first com- menced, tiiat the bacteriological cultivations and counts of the samples of water would be made under the direction of the Super- intendent of Health, I did not assume any direct responsibility in regard to the bacteriological work until early in September. At this time I commenced to personally investigate the subject, and was asked by the Superintendent of Health to make any sugges- tions that I deemed advisable and to give such directions as I thought proper in regard to this work. After making myself familiar with the methods that were generally followed in this country and abroad, and consulting with Professor II. C. Ernst of FILTRATION EXPERIMENTS. 43 the Harvard University Medical School, who had made some test counts for us upon two occasions, I came to the conclusion that the bacteria had not been cultivated long enough to reach their highest growths, and that the " Fifteen-per-cent Gelatin " that had been used, nearly the whole of the time, should be discontinued and " Ten-per-cent Gelatin" used, which is the nutrient media generally made use of in the cultivation of water bacteria. The majority of the counts from March 27 to October 6, 1893, had been made after a cultivation of from 42 to 62 hours. Subse- quent investigations have proved that these counts were made too soon, and that more bacterial colonies would have been visible when the counts were made, if a longer period had been allowed for cultivation and "Ten-per-cent Gelatin " used. I am, therefore, of the opinion that the bacteriological counts that were made from March 27 to October 0, 1803, are not strictly reliable, and should onl}^ be used for comparing the efficiency of the different filters. The application, however, of a slight correction, derived bj 7 com- paring the counts of from 42 to 62 hours with results that have been obtained since October 6, 1893, tends to show, when Basic Sulphate of Alumina and "Free Flow" were used, that an average of about ninety-nine (99) per cent, of the Applied Water bacteria was removed by the Morison Mechanical Filter, from March 27 to October 6, 1893. This average percentage, if it had not been cor- rected, would have been slightly more than ninety-nine per cent. Owing to the reasons given above, the only bacteriological work which I shall mention, and describe hereafter, unless otherwise specified, will be the work that was done later than October 6, 1893, or that which was done previous to that time by Professor H. C. Ernst, The method used in cultivating the bacterial colonies was the familiar method of gelatin-plate culture devised by Koch. The bacterial colonies were grown at the laboratory tempera- ture. The bacterial colonies visible in each dish were first counted after a cultivation of about 42 hours, and subsequently about every 24 hours until an increase in their number could no longer be detected. It was then assumed that their end growths had been reached. The entire length of time necessary for cultivation ranged from 67 to 236 hours. A great deal of trouble was caused by the bacterial colonies liquefying before end growths w r ere reached (from October 17, 44 FILTRATION EXPERIMENTS. 1803, to January 30, 1894, all of 51 (lays' samples were lost on this account), and it was deemed advisable on December 12, 1893, to discontinue using one (1) cubic centimeter from each sample of Filtered Water which had previously been used in eacli dish and to use four dishes for each sample with one-fourth ( 7 1) of one (1) c.c. in each dish. This method, though being an improvement upon the use of one (1) c.c., was not entirely satisfactory, and on December 2(>, 181)3, another change was made, namely : the equal division, from each sample, of one-half (-J) of one (1) c.c. among five dishes. This latter method was followed until the completion of the work, and very little inconvenience was experienced from liquefying colonies during this time. A check was kept upon it by frequently culti- vating one (1) c.c. in one dish, from the same sample that one- half (^) of one (1) c.c. divided by five (5) was taken from, and the average result obtained from all the one (1) c.c. cultures, which could be kept 137 hours or more without liquefying, was almost exactly the same as the average of the one-half (4) of one (1) c.c. divided by five (5) cultures that were taken from the same samples. Four dishes, each containing 1 --J-- of one (1) c.c. of Applied Water, were used in making the cultures of the Applied Water, with the exceptions which will be mentioned hereafter. The methods of cultivating the samples of Filtered Water, when Bacillus Prodigiosus was being added to the Applied Water, were the same as those that have previously been described ; but only in a few instances was it possible to ascertain, on account of liquefaction, if end growths had been reached. But as it is gen- erally customary to count cultures of these bacilli after from 48 to 90 hours growth, and as table No. 19, giving the results that were obtained when they were being applied, shows that the samples of Filtered Water were cultivated from 41 to 208 hours before they liquefied, and the samples of Applied Water from 40 to 190 hours, there is not any doubt, I think, but what the percentages given in this table are sufficiently reliable. A pure culture of Bacillus Prodigiosus was obtained, by inocula- tion and growth for about four days, in the following solutions, namely : On November 22, 23 and 25, 1893, one (1) liter of Bouil- lon ; on the 28 and 29, four (4) cubic centimeters of the above Bouillon in one (1) liter of tap water ; on December 2, f> and G, a solution of one-tenth (-f^) per cent. Peptone, and two-tenths (f^) FILTRATION EXPERIMENTS. 45 per cent. Glucose in tap water; on the 12, 13 and 14, four (4) cubic centimeters of the above Peptone and Glucose solution in one (1) liter of Sterile Water; on the lf> and 10, tive (/>) cubic centimeters of the Peptone and Glucose solution in one (1) liter of Sterile Water; on the 18 and 10, four (4) cubic centimeters from one (1) liter of Bouillon and " Ten-per-cent Gelatin" in which the culture was made, in one (1) liter of Sterile Water ; on the 20, 21 and 22, the full Peptone and Glucose solution ; from December 3, 1803, to January 3, 1804, inclusive, one-tenth (y 1 ^) of the Peptone and Glucose solution in one (1) liter of tap water ; and from Janu- ary 4 to 8, one-twentieth (-$) of the Peptone and Glucose solution in one (1) liter of tap water. The Bacillus Prodigiosus Solution was uniformly applied by being di'opped into the filter from an earthen jar located upon the top of the filter. Cruikshank's Bacillus, that was prepared and used in a man- ner similar to the Bacillus Prodigiosus, was added to the Applied Water on July 27 and August 17, and on October 11 and 12, 1803, at the rate of more than one million (1,000,000) per cubic centi- meter. Three (3) colonies of this bacillus were found, after a cultivation of five days, in the sample of Filtered Water that was collected on July 27. None were discovered in the samples of Fil- tered Water that were collected on the other days mentioned. The samples of Applied Water containing the Bacillus Prodigi- osus were drawn from a stop-cock connected to the filter about seven (7) inches above the filter-bed. Samples of the Applied Solution were also taken during each run, and if the samples from the top of the filter liquefied in cultivation, the number of Bacillus Prodigiosus in the Applied Water were estimated from the num- ber in the Applied Solution. The Bacillus Prodigiosus Applied Water was generally culti- vated in four dishes, two, each containing T oV c.c. and two, each containing yoUo c.c. The Applied Solution was cultivated in two dishes, each generally containing roooooo c.c. The proportions of ,077 <^<'- of the Applied Water and the Woo c.c. and TOOOO c.c. of the Bacillus Prodigiosus Applied Water and the Tooiooo c.c. of the Applied Solution, were obtained, for culti- vation, by diluting with Sterile Water of known volume. The proportions of one-fourth (^) of one (1) c.c. and one-tenth ( T 1 ,,) of one (1) c.c. of the Filtered Water were obtained by direct meas- urement without dilution. 46 FILTRATION EXPERIMENTS. The samples of Applied Water (not containing Bacillus Pro- digiosus), were collected from a tap in the pipe which supplied the filter with water. All samples of Filtered Water were col- lected at the outlet of the discharge-pipe of the filter. The gelatin used in the bacteriological work was tested for alkalinity up to about the first of November with litmus paper and after that time by the " phenol- phthalein test." The following table, computed from results obtained in our laboratory, shows the Ratios of the growths of bacterial colonies in " Ten-per-cent Gelatin," over what they were in "Fifteen-per- cent Gelatin," etc. NlTMBEK OF HOURS OF CULTIVATION, ETC. 00 Cfl m as ft ft ft a ft CO s a g a QO CC ci CC CD 05 CO en CO t CO n 0) ^' C O o o o o OF 1 a to +1 1 4-1 1 a 1 K -ft: a w 4-1 o O) fl 5 * % SB CO CO 3 1 .08 3 1 . 36 3 1 58 C) 1 . 09 1 0.94 14 10 1 .0(5 \ 10 1 14 10 1.01 9 0.85 7 . 79 15 4 3 . 00 4 1.16 4 1.17 3 1 . 28 16 1 1 53 1 *1 31 18 16 1 . 23 8 1.18 19 16 1 . 33 8 1.41 i .... .... .... ... 20 18 1 . 89 ! 18 1 . 69 12 1 . 62 2J Average ratios. 1.60 1.32 1 . 35 1.07 0.87 *Not included in averages. The above table indicates that nearly the same results can be obtained with " Fif teen-per-cent Gelatin " as can be obtained with FILTRATION EXPERIMENTS. 47 " Ten-per-cent Gelatin," if the bacteria are grown more than 113 hours. The Bacteriological Work, in the laboratory was clone from March 27, to December 10, 18U3, by Dr. G. T. S warts, Medical Inspector, with the exception of several short periods of time, when it was done by Dr. C. V. Chapin, Superintendent of Health. From December 11, 18!)3, to January 31, 181)4, the work was done by Dr. M. T. Richardson, a graduate of the Harvard University Medical School, who was recommended by Professor H. C. Ernst. The remainder of the time, from February 1, to February 12, the counts were made by myself. Since October 1, I have had consultations in regard to the Bacteriological Work, with Professor H. C. Ernst of the Har- vard University Medical School, Professor E. K. Dunham of the Carnegie Laboratory of New York, and Professor T. M. Prudden of Columbia College. These gentlemen, all of whom are expert bacteriologists, have signified their approval of the methods that have been followed in regard to the Bacteriological Work, since October G, 1893. DESCRIPTION OF TABLES. All, of the tables from No. 2 to No. 21 inclusive refer to the Experimental Morison Mechanical Filter. The columns in the Bacteriological tables from No. 2 to No. 8 inclusive headed "Grains of Sulphate of Alumina used per Gal- lon," include " Free Flow." The rate of Alumina (not including "Free Flow"), that was added constantly to the Applied Water, was gauged very carefully and it was intended to apply it at a specific rate per gallon, as the case might require, of one-half (-J) grain or three-fourths (f ) of a grain (or more or less). This could not always be done in actual practice, however, as the outlet of the " dropper " was so small that it would sometimes clog up in spite of constant watchfulness and testing. The computed average rate, including " Free Flow" and a constant addition of Alumina at the rate of one-half (TT) grain per gallon, would be fifty-nine one- hundreths ( f Vo) of a grain for an average length of run of Ifi hours and 43 minutes and an average rate of filtration of 128,000,000 gallons per Acre per 24 hours, and under the same conditions the computed average rate, including " Free Flow " and a constant addition of three-fourths (f) of a grain of Alumina per gallon, 48 FILTRATION EXPERIMENTS. would be eighty-four one-hundred ths (ro 4 o) f a grain. The quan- tity of " Free Flow " used was always the same, therefore an in- crease or decrease in the length of the run would of course change the computed average rate of Alumina used during the entire run, and a slight deviation one way or the other in the quantity of water filtered would also change the average rate of Alumina used. More than the usual care was exercised in all gaugings of both Alumina and Water for at least one-half hour before the samples of Filtered Water were collected. Tables from No. 2 to No. 10 inclusive give the Bacteriological Results that have been obtained and the percentages of the Bac- teria in the Applied Water that w r ere removed by filtration, com- puted from the same. Only one sample of Applied Water was generally collected each da} 7 , the hour of collection in the great majority of cases being from 12 M. to 1 P. M. The samples of Filtered Water were collected as will be seen from the tables, from One (1) to Ten (10) times daily. Table No. X gives the End Growths or positive results that were obtained from Samples of Filtered Water that were collected at the Same Hour as the Applied Water, once during each rim, generally from 12 M. to 1 P. M., One Hour or More after water commenced to flow from the filter. Table No. 3 covers the same ground as table No. 2, with the ex- ception that it is computed from counts that were made after a cultivation of about Ninety Hours. This table was made for comparison with table No. 2, as it is generally customary to make the counts of water bacteria after they have been cultivated about four days. Table No. 4 gives the End Growths or positive results that were obtained from Samples of Filtered Water that were collected from One (1) to Nine (9) times each day, One Hour or More after water commenced to flow from the filter. The percentages were all based upon results derived from the single sample of Applied Water that was generally collected from 12 M. to 1 P. M. daily. Table No. 5 gives the End Growths and all of the Growths of Eighty Five Hours or More, that did not reach their End Growths, that were obtained from Samples of Filtered Water that were col- FILTRATION EXPERIMENTS. 49 lected from One (1) to Nine (9) times each day, One Hour or More after water commenced to flow from the filter. The percentages were all based upon results derived from the single sample of Applied Water that was generally collected from 12 M. to 1 P. M. daily. Table No. 6 gives the End Growths or positive results that were obtained from Samples of Filtered Water that were collected Thirty Minutes or Less after water commenced to flow from the filter. The percentages were all based upon results derived from the single sample of Applied Water that was generally collected from 12 M. to 1 P. M. daily. River Water was used in washing the filter, with the exception of on November 15, 17, 18, 20, 23 and 24, when Filtered Water was used. Table No. 7 covers the same ground as table No. 6, with the ex- ception that it was computed from counts that were made after a cultivation of about Ninety Hours. This table was made for com- parison with table No. 6, for the same purpose as is mentioned in the description of table No. 3. Table No. 8 gives the End Growths and all of the Growths of Eighty Five Hours or More, that did not reach their End Growths, that were obtained from Samples of Filtered Water that were col- lected Thirty Minutes or Less after water commenced to flow from the filter. The percentages were all based upon results derived from the single sample of Applied Water that was generally col- lected from 12 M. to 1 P. M. daily. In tables Nos. 2, 3, 4, 5, 6, 7 and 8 during the time that Bacillus Prodigiosus was used, the number of bacteria in the columns headed " In Filtered Water," include the Bacillus Prodigiosus, when there were any, found in the Filtered Water. (See table No. 19). If they had not been included, the average per cents, of the "Applied Bacteria Removed," would be slightly larger and a few of the individual per cents considerably larger. This does not affect, however, any of the final results or conclusions which will be mentioned hereafter in this report, for reasons which will be subsequently explained. The average percentages given in the tables from No. 2 to No. 7 50 FILTRATION EXPERIMENTS. 8 inclusive, which are not inclosed in parentheses, and which were considered as a basis for all' comparisons and summaries, were ob- tained by averaging the individual per cents given in the tables. The average percentages obtained by using the total number of bacteria found in the Applied and Filtered Water are also given in the tables, inclosed in parentheses, in order to show the differ- ence between this method of computation, which is sometimes fol- lowed for obtaining average bacterial percentages, and the method just previousl} 7 mentioned. The average percentages obtained by using total numbers, as can be seen by inspecting the tables range from 0.0 to 3.1 more than the averages obtained by using the indi- vidual per cents of each sample. Tables Nos. 9 and 10 were computed from tables Nos. 2, 3, 4, 5, G, 7 and 8, and give Summaries of the Average Percentages of Ap- plied Water Bacteria that were Removed by the filter. The averages obtained by "totals "are also given in parentheses in these two summaries. They were obtained in the same manner as described above for tables from No. 2 to No. 8 inclusive. Tables from No. 11 to No. 18 inclusive, were computed from tables Nos. 2, 3, 4, 5, G, 7 and 8. Tables Nos. 11 and 15 give the number of times that Percentages of More than Two Per cent., of the Applied Water Bacteria, Ap- peared in the Filtered Water. Also the Percentages that the number of times are of the Total Number of Results obtained. Tables Nos. 12, 14, 16 and 18 give the number of times that Per- centages of the Applied Water Bacteria Removed, which were used in working up the Average Percentages given in tables Nos. and 10, were One Per cent, and More Less than the average Per cent. Removed. Also the Percentages that the number of times are of the Total Number of Results obtained. Tables Nos. 18 and 17 give the number of times that Percentages of the Applied Water Bacteria Removed, which were used in working up the Average Percentages given in tables Nos. 9 and 10, were More than Two Per cent. Less than the Average Per cent. Removed. Also the Percentages that the number of times are of the Total Number of Results obtained, FILTRATION EXPERIMENTS. 51 Table No. 19 gives the Percentage of Applied Bacillus Prodigio- sns that was Removed from the water by filtration. Also the number of these bacilli that were found in the Applied and Fil- tered Water and the length of time that they were Grown. The ''Last Growth obtained," mentioned in the table, was the last growth that could be obtained before the bacterial colonies lique- fied. The Average Percentages given in the table were obtained in the same manner as the averages given in tables from No. 2 to No. 8 inclusive. The quantity of Alumina used per gallon of Applied Water is given in the latter part of the table. Table No. 20 gives the Chemical Analyses of Applied and Fil- tered Water that were made during the experiments with the Experimental Morison Mechanical Filter, by Professor J. PI. Ap- pleton. Table No. 21 gives the Color of samples of Applied and Filtered Water that were collected during the experiments with the Ex- perimental Morison Mechanical Filter, and the Percentage of Color that was Removed from the Applied Water by filtra- tion. Table No. 22. As the elaborate and very valuable experiments relative to the Natural Filtration of water, that have been made at Lawrence, Massachusetts, under the direction of the State Board of Health of Massachusetts, during the past few years, are recognized, I think, by the engineering profession the world over, as being the most complete exposition of the subject that has ever been made, table No. 22 has been compiled from the Report of the State Board of Health of Massachusetts for the year 1892, in order to make, in a few instances, a general comparison of some of the results that have been obtained at Providence with the Morison Mechanical Filter with some of the results that have been obtained by Natural Filtration with Experimental Filters at Lawrence. The Massachusetts Report states, relative to some of the data that has been used in computing the table, namely: "It has" "been found, however, that the true degree of bacterial purifica-" "tion is somewhat obscured by the presence in the effluent of" " bacteria which have not come down through the filter directly " " from the Applied Water. Some of them appear to have their " 52 FILTRATION EXPERIMENTS. "origin in the outlet-pipes and underdrains where they continue" ' to live upon the very slight amount of food present. This is " "especially noticeable during the warm summer months when" " a few of the more hardy species grow upon the organic matter " " stored at the surface." The principal object of table No. 22 is to show the number of times that Percentages of One Per cent, and More, of the Applied Water Bacteria, Appeared in the Filtered Water of the different filters, the number of times that the Percentages of Applied Water Bacteria Removed were One Per cent, and More Less than the Average Per cent Removed, and the Percentages that the num- ber of times are of the Total Number of Results obtained ; and to show the Percentages that the number of times that More than Two Per cent, of the Applied Water Bacteria Appeared in the Filtered Water, are of the Total Number of Results obtained, and the Percentages that the number of times, that the Percent- ages of the Applied Water Bacteria Removed that were More than Two Per cent. Less than the Average Per cent. Removed, are of the Total Number of Results obtained. The above results were calculated from data given in the tables of the Massachusetts Report, above mentioned, on pages from 491 to 524. The average rates of filtration given in the Seventh column, of the First part of table No. 22 were obtained by averaging the daily rates of filtration, from June to November inclusive, of the days when both samples of Applied and Filtered Water were col- lected (given in the Massachusetts Report on pages from 491 to 524), with the exception of the rates of those days when the num- ber of bacteria in the " Effluent" exceeded the number in the Applied Water, and are therefore somewhat approximate. The Average Percentages of Bacteria Removed, not inclosed in parentheses, given in the Ninth column of the First part of table No. 22, were obtained by averaging the individual per cents worked out from daily samples, taken from June to November inclusive, given in the tables of the Massachusetts Report on pages from 491 to 524, with the exception of those cases in which the number of bacteria in the " Effluent " exceeded the number in the Applied Water, (viz : 2 in 33 A ; 3 in 34A ; 3 in 36 A ; 2 in 37 ; 1 in 38 ; 1 in 39 ; 2 in 40). The Massachusetts Report states, in a note under the tables of December bacterial results, that "Channels were formed in the sides of the filters," and on page 477 that "This took place to a greater or less extent in the case" FILTRATION EXPERIMENTS. 53 "of all the small filters, and the results obtained in December " "have not for this reason been included in the discussion." The number of results used in working out these percentages is given in the Second. Third and Fourth parts of table No. 22. The per- centages were computed in the manner above described in order to compare them with the results obtained with the Morison Mechanical Filter, as, has previously been explained, the per- centages given in the tables relating to the Morison Mechanical Filter, that have been considered in all comparisons and summa- ries, were obtained by using individual per cents which were worked out from all the results obtained while the filter was in its normal condition, there not being any results rejected on account of excessive numbers of bacteria being found in the Filtered Water. The figures inclosed in parentheses, given in the Ninth column of the First part of table No. 22, were obtained by averaging the individual per cents of daily samples in the same manner as the percentages which are not inclosed in parentheses, with the excep- tion that samples were not considered in which the number of bacteria in the "Effluent" exceeded 500. These percentages were computed by this method in order to show the difference that the rejection of the last mentioned samples would make in the aver- age percentages. A foot-note at the bottom of the tables in the Massachusetts Report states that " Numbers above 500 do not appear in the " "averages (see page 530)." The information on page 530 of the Massachusetts Report, referred to in this note, relating to the sub- ject, is as follows : " The statistics in the tables (pp. 400-525) " "show that all of the effluents at times contained very large" "numbers of bacteria during July and August. In some cases" "they equalled and even exceeded the number applied. This" " was least noticeable in case of the intermittent filters Nos. 35 A " "and 41. Some error in the process of determination was at first" "suggested as the reason for this. Detailed study of the condi-" "tions under which the examinations were made, however, to-" "gether with the results of more numerous examinations, indi-" "cated that this was not so. It then appeared that there must" "be present in the filters at times conditions which favored the" "growth of certain kinds of bacteria." The figures given in the Tenth column of the First part of table No. 22, not inclosed in parentheses, are percentages of removal 54 FILTRATION EXPERIMENTS. worked out by using the total number of bacteria found in the "Effluent" and Applied Water of each filter during the entire period above specified, instead of from individual results. In other respects the same method was followed as was used in work- ing out the percentages given in the Ninth column. These per- centages were computed in order to compare them with the cor- responding percentages given in the Ninth column. The average percentages given in the Tenth column inclosed in parentheses, were worked out in the same manner as those not inclosed in parentheses in the Tenth column, with the exception that samples were not considered in which the number of bacteria in the "Effluent" exceeded 500. These percentages, which were also computed in order to compare them with the corresponding percentages given in the Ninth column, were worked out in a man- ner similar to the method followed in working out the bacterial percentages given in the Massachusetts Report. The Average Percentages given in table No. 22, considered in making all comparisons with the results obtained with the Morison Mechanical Filter, unless otherwise specified, were computed by averaging the individual per cents of daily samples including samples in ivhich the bacteria in the "Effluent" exceeded 500, with the exception of those samples in which the number in the " Efflu- ent " exceeded the number in the Applied Water. As can be seen by the table the average per cents obtained by this method range from 0.5 to 2.8 less'than the averages computed by using, as men- tioned above, the total number of bacteria found in the "Effluent" and Applied Water. FILTRATION EXPERIMENTS. 55 TABLE No. 2. FILTRATION EXPERIMENTS. MORISON MECHANICAL FILTER. END GROWTHS, of Water Bacteria in the Samples of Applied and Filtered Water that were taken at the SAME HOUR ('which icas One Hour or More after 'water commenced to flow from the filter). DATK. Gallons of Water Filtered per Acre, per 24 Hours. Bacteria per Cubic Centimeter. Per cent, of the Applied Bacteria Kemoved. Averaee ( ... f Percentage ./^of Awn!* Al ;;r &! .- In Applied Water. In Filtered Water. 1893. July* 20, " 01 *j, Oct. 3, 4, 5, Oct. 17, u 27 30J 31, Nov. 1, " O * 3, 4, 9, " U, Nov. 23, " 24, Dec. 2, 4, 1894. Jan. 2, 3, 4, 5, U Q Q 8) 125,000,000 122,000,000 125,000,000 128,000,000 131,000,000 125,000,000 122,000,000 128,000,000 131,000,000 132,000,000 123,000,000 122,000,000 132,000,000 125,000,000 125,000,000 Com 120,000,000 132,000,000 125,000,000 128,000,000 132,000,000 137,000,000 132,000,000 130,000,000 130,000,000 c< 2,000 9,477 905 010 4,002 0,175+ 10,700 1,700 500 21,200 7,000 12,500 4,100 3,300 3,800 menced to use 15,850 14,000 0,000 4,475 2,850 3,375 5,025 3,775 4,000 jased to use B 11 10 2 25 43 44 12 16 28 34 66 101 35 20 s Bacillus Pr 218 304 190 91 178 192 136 142 360 acillus Prod 99.5 99.8 99.3 99.7 99.4 99.3 99.0 99.3 90.8 99.9 99.0 99.5 97.5 98.9 99.3 odigiosus. 98.0 97.4 90.8 98.0 93.8 94.3 97.3 96.2 91.0 igiosus. 0.75 0.90 0.00 0.58 0.55 fO.57 0.01 0.50 0.59 0.01 0.81 0.84 11.20 0.85 0.82 0.00 0.59 || 0.50 0.00 0.85 0.84 0.85 0.82 0.58 99.5 "OMreT" 99.0 .(99.4) 95.9 (96.8) 56 FILTRATION EXPERIMENTS. TABLE No. 2. CONCLUDED, DATE. Gallons of Water Filtered per Acre, per 24 Hours. Bacteria per Cubic Centimeter. Per cent, of the Applied Bacteria Removed. Average Percentage of the Applied Bacteria Removed. Grains of Sulphate of Alumina u0, 44 OO " 23; Jan. 24, 25, 20, 27, " 9 " 30^ 130,000,000 3,400 134,000,000 1,725 130,000,000 2,150 132,000,000 875 132,000,000 1,033 134,000,000: 1,000 134,000,000 775 130,000,000 3,375 134,000,000 3,800 130,000,000 2,707 130,000,000 5,200 132,000,000 11,200 132,000,000 4,133 Washed filter-be 128,000,000 5,025 125,000,000 3,000 128,000,000 10,700 128,000,000 7,507 128,000,000 3,100 130,000,000 3,000 148 108 84 ' 274 08 184 178 150 102 200 230 340 -278 cl with Caus 24 30 117 123 120 70 95.0 1)3.7 90.1 08.7 95.8 88.5 77.0 95.0 95.7 92.0 95.0 90.9 93.3 tic Soda. 99.5 99.0 98.9 98.4 96.1 97.7 0.00 0.84 0.01 0.81 0.72 0.84 0.58 0.82 0.59 0.83 0.72 0.85 0.80 0.00 0.82 0.58 0.58 0.59 0.58 91.2 ~~(94~3) ' 98.3* (98.5) *The counts from July 20 to July 21, and from Oct. 3 to Oct. 5, were made by Professor H. C. Ernst. tOne-half "Free Flow." ^ One-half grain when sample was taken. ; Docs not include " Free Flow " although it was used. Temperature of Applied Water 71. FILTRATION EXPERIMENTS. 57 TABLE No. 3. FILTRATION EXPERIMENTS. MORISON MECHANICAL FILTER. Growths of about NINETY HOURS, of Water Bacteria in the Samples of Applied and Filtered Water that were taken at the SAME HOUR (which was One Hour or More after water commenced to floiv from the filter). DATE. Gallons of Water Filtered per Acre, per 24 Hours. Bacteria per Cubic Centimeter. Per cent, of the Applied Bacteria Removed. Average Percentage of the Applied Bacteria Removed. Grains of Sulphate of Alumina used per Gallon. In Applied Water. In Filtered Water. 1893. July *20, " 21, Oct. 3, " 4 ^ Oct. 17, 27, 30, 31, Nov. 1, u o w ? 3, 4. 9, U, Nov. 23, 24, Dec. 2, 4, 1894. Jan. 2, 3, 4, 5, U CJ Q v o 125,000,000 122,000,000 125,000,000 128,000,000 131,000,000 125,000,000 122,000,000 128,000,000 131,000,000 132,000,000 123,000,000 122,000,000 132,000,000 125,000,000 125,000,000 Com 120,000,000 132,000,000 128,000,000 128,000,000 132,000,000 137,000,000 134,000,000 130,000,000 130,000,000 r, 2,000 9,477 905 610 4,002 6,175+ 9,700 1,700 400 15,112 6,950 9,400 3,400 2,200 3,650 menced to us 15,850 7,600 4,900 4,475 2,150 2,000 2,275 1,925 2,375 11 16 6 2 25 26 41 7 9 19 26 50 63 26 25 3 Bacillus F 218 364 190 91 94 118 44 60 184 99.5 99.8 99.3 99.7 99.4 99.6 99.6 99.6 97.8 99.9 99.6 99.5 98.1 98.8 99.3 rodigiosus. 98.6 95.2 96.1 98.0 95.6 94.1 98.1 96.9 92.3 0.75 0.90 0.60 0.58 0.55 fO.57 0.61 0.56 0.59 0.61 0.81 0.84 J1.20 0.60 0.82 0.60 0.59 ||0.75 0.60 0.85 0.84 0.85 0.82 0.58 99.5 (99.6) 99.2 (99.5) 96.1 (96.9) 58 FILTRATION EXPERIMENTS. TABLE No. 3. CONCLUDED. DATE. Gallons of Water Filtered per Acre, per 24 Hours. Bacteria per Cubic Centimeter. Per cent, of the Applied Bacteria Removed. Average Percentage of the Applied Bacteria Removed. Grains of Sulphate of Alumina used per Gallon. In Applied Water. In Filtered Water. 1894. Jan. 9, 10, 11, 12, " 13, " 15, " 16, " 17, 18, 19, 20, 22, 23, Jan. 24, 25, " 20, 27, " 29, 30, 130,000,000 134,000,000 130,000,000 132,000,000 132,000,000 134,000,000 134,000,000 130,000,000 134,000,000 136,000,000 130,000,000 132,000,000 132,000,000 Wa 128,000,000 125,000,000 128,000,000 128,000,000 128,000,000 130,000,000 1,850 800 750 350 600 925 375 2,150 1,500 1,450 2,800 3,350 2,300 shed filter-be< 2,100 2,225 4,650 4,875 1,575 1,400 54 28 20 52 36 88 44 64 62 80 58 62 64 1 with Cam 6 18 54 72 82 28 97.1 96.5 97.3 85.1 94.0 90.5 88.3 97.0 95.9 94.5 97.9 98.1 97.2 >tic Soda. 99.7 99.2 98.8 98.5 94.8 98.0 0.60 0.84 0.61 0.81 0.72 0.84 0.58 0.82 0.59 0.83 0.72 0.85 0.80 0.60 0.82 0.58 0.58 0.59 0.58 94.6 (96.3) 98.2 (975) * The counts from July 20 to July 21, and from Oct. 3 to (Jet. 5, were made by Professor H. C. Ernst. t One-half "Free Flow." $ One-half grain when sample was taken. il Does not include "'Free Flow" although it was used. Temperature of Applied Water 71. FILTRATION EXPERIMENTS. 59 i 3 ^ eg 1 ^ 8 s 35 s^fil ?&!? !S-- 10 o o oo 10 L^. 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I T H rH r " a a a a a a a a a a s a a a a a a a a a a a a a a a a a oooooooooooooooooQQ. 00*000 oooo i O5 oi rH CC ^ OS QO 64 FILTRATION EXPERIMENTS. ilii 0^^^^^000000000000,00 0*3 s o> oooooooooooooo C"d |S|I| 25 2 > **" S a w* 3 "^ o ClCiciciCiCiOiOiCiCiOCiCiCS 1 >. ^5 ft H ft i, 1 rH rH rH i 1 1 s 2 o ^ o" P HI O fc o >o ooooooooooooo CMOOOOOOOOCOCDOOO 1 ^o CO T3 S <* s s ocococococoooooocococo rH rH rH s i 0) o' 1 S 1 1 g 6 -It. O O> O"W 0000000000000 <^> <^> <^> <^) C^) ^^ CO C^j C^> CT^i C~^i (T*!!) C^!) T3 ^ -S s rj S* w M Ijll j gSflJp ^S s fr!^^ ooo^ooooooooooo 0000000000 o o o ooooooooooooo 5J >) -2 S c g 3 * CS - ^,0> > " -3 o ^ fe ? S 0) X TO C -2 o ^ gj, E" 1 8 r 1 1 i 0? C fl C ^ ^ 5 5 fl ^ S 03 S 2 M 2 ~ S C pt| ^ !3 p< ^^ 1 o ^ S 1 o 1 Id gggggg g^gg g "- 1 W -2 i g g 2 8 Vr ^ S Q) $& "S^ 3 8i88S3a3S885Sa fl "3 rfl (D 01 SS ^ g fl s fl s r i -8 g ^ ^ S rH rH c * -- S H H H- = c*s : w E-c P o ^ ^ 00 ~ ^ rH Gl Cl G*l Ol CO o FILTRATION EXPERIMENTS. 65 S ^ ^'"'P c t^ CO O rHOOSrHrHTJHOtOlOC^OOiO tOOOOCOtOOCOOOOOC i- -*-> f^^j O S S ^ ^ S i>i -rf* U CD ^ ^ S; O ^ I 5 f tf a S 03 ^' ^0373 CO "rfH OS CO CO OO OS CO O 4 O OS O CO CO t> << |1 Plli OOStcosOiOOSOSOJt^OOOOOSOOOi OSOSOSOSOSOSOSOiOSOSOSOSOSOSOS MECHANIC. *^3 Q* ^* ^"S ^j ^~> *iO o ,g > 3 n^ts cocoos^oicooo-ticorHiocococ-qo T^t>-C- tO rH to X ^ Q GO Hi cs +3 'E S ' ^ f o . ^ ^fe tO O^ ^O 1 O> O^ ^) '^^ O^ ^D < O J '-^^ O^ O^ O> cO t>-OCMOOOOOOOOtoOOO TiL^-OL^-L'>-tOG OO OO CO fc H O ^ o COrHCOOrH rHL^G^^COTtlCOCO^ rH rH rH ^ rH CM 13 PQ ^ 1. S i ? ?llg 00000000000000 oooooooooooooo ooooooooooooooo H f^! "^ 111 ooooooooooooooo (^ ( O ) O 5 ^O O> O 5 O> O 3 O> O^ ^O 1 t ^^ O^ ooooooooooooooo 3 w ^ " g ^ll^ iO CO ^O O^l OO TT^ C^^ CO Ol C 1 ^ ^O OO *O ^O ^O kj <~ ^~ K( ^ S * o !r 0) "p, H ^ is g s s s s s ^ H iJ e ;s 1 i! G^ C^J O^ G^l G^l C"} ^1 C^l C^ G'l to ^D to to to i i r^H fc| r CO O O CO CO CO rH rH fe ^ CO "o* . rH H O t^CO-r^t^OrHrHG^ CO ^ OS O rH to t> r 1 C3 I t>. o" o o >d CM' id ' ' 'Sb w ^" * "* ""* *" " '"" ' " "^ 1 ft w p || " BO 3 JO 3 CM r-i GO CO 00 CO CM CM O T-I ^H -^ ^H O O t^ ^ CO O P3 O5 ii CM CM ^ JH CM' L^ t^ ^H CO CO CO T i?H i^H Cl CO CM ONTIN 11 1. t? c* o "*-* p ^ OOOOOOOOOOOOOOOOOOO o UO iO O iO iO iO iO O O O O O O O O O O O O t^ C CO CO CO GO -GO CO CO CO O O O O O O O O -* CM CM <3j| O fl X O 'O iO 'O IO iO IO 'O ^ -^H -sfi -^H TJH Tf -r^l ^ CO "^ -^ . * o Q Q) ^ o ooooooooooooooooooo o ooooooooooooooooooo o ooooooooooooooooooo H E1 OOOOO ! OOOOOOOOOOOOOO" ooooooooooooooooooo O OOOOOOOOOOOOOOOOOO-O PQ Sis* Q\ CO O O 'O GO CM CM GO CO CO CM CM 00 il T 1 CM >O OO d CO T i CM C>1 CM ^M CO CO Ol ^ T^i CO CO CM O-1 CM CO CM CM CO I g g g g g g g s g g ^ g g ^ g ^ g ta-^ 43 03 -^ 05 iO OOCMOOOOCOOOOCMOOOOOOO CO OOi lOOO^^OOOrHOOO^OCOCO O W CO Or- 1 rHCMCOCOiOOiOT-l 1-HCMCOCOOC5O T 1 rH rH rH rH H H ft CO CO O5 O V, v. ^ 00 00 "* - ^ rH r 1 rf r co tT lo^cxT ^ CM CM CM CM o o .^ s ^ FILTRATION EXPERIMENTS. 67 CO O O to 'O to b~ l>- O- t^ O iO O to to to to to to to to to CO O 'tO OOCOOOCOCOtOOOO^CX3CiO5rHCOOOCOOOOCOO5CftOTHOOQOrH CO O CM CO CM O -rp d CO -M O CO CO -fi CO CO CM CO CO rH O l> rH C5 tO L-^ to CM G-l L^ CM C<1 T I O5 rH rH rH rH r-irHOli I T IrH C-lrHrHrHrHrHr-i OOOOOOOOOOtoOOOOOOOOOOOCOCOCOCOCOCOCOCO OOOOOOOOOOI^OOOOOOOOOOOCOCOCOCOCOCOCOCO oooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooo O^O^O^O^O^O^O^O^O^O O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O O O' oooooooooooooooooooooooooooooo ( ^^ O^ O ; ^O O ) ^O ( O | O^ O> ^O O^ 1 ( ^ ) ^O C^ c^ (^ (^> (^^ t^) c^) <^ (^ CM co oc" co" to" to" co" co" o to" co" co" "* CM" co to" cc" co" to" r-T co" co" -H^ -^ c> -rtT -rin" o" TI" ci" CO CM O5 CM CM CM CM (M CM CM CM CM CO CO CM CM CM CM CM CO CM CM CO CO CO CO CO CO CO CO g g g g g g g g g g . gggggggg g g g g g g g g g g g OtoOOOOOOOOCMtoOOOOOOOOOOOOOOOOOtO COrHCO(TOCOCOCOCOCO^rHtoOOCOCOCOCOCOCOHHCOCOCOCOCOCOCO^T^ r-i CM CM Oi d rH CM* rH CM CO ^ rH O C5 O r-H CM* rH CM CO O O5 O r- i O5 rH CM CO to' CO CO" SSSSS ^ ^ T I co" CM HjTt>-^co cs CM co T^H CM rH rH ^H OO) ^^^^^ ^ ^ fa O FILTRATION EXPERIMENTS. TABLE No. 5. CONTINUED. ll O *O lO 1O *O *6 1C O O ^D O O O :r> tD CO [> t>- b- !> L^ L^ L^ OOOOOOOOOOOOOOOOOOOOOOO 'o-c! . OS CO CO OS OO rH GO OS CD OO H^ OO *O *O H^ O O CO CD rH CO *O CO CO t^.' 1C* CO* CO* 00* t>* t>* t>* t>" GO* GO* OS* 00 00* OS OO OO l> t>* t>* GO* GO* CO* CO* rH I>* t>* OS HH CO GO COC^CMCM^CMCOCOOCO OO O O TH ^ O COCMrHiOOSiHCOO OO O O GO CO CMCOCOCOi IrHrHrHrH rHrHrHrH rHrHOIHHCOCOt^rHrH OOOOOOOOOOOOOOOOOOOOOOOOOOOiO00 GO" co" co" GO" co" o^ 10^ i^T i^T ^o o^ co" co" co" co" co co" co" co" co" co" co" co" co" CM" CM" CM" CM" CM CM OOO O OOOOOOOOOOO O OOOO'OOOOOOOOO CZ^ ^> CZ^ CZ^ CZ^ CZ^ ( ^D CZ^ (^ CZ) ^^ CZ> CZ^ CZ^ CZ) CZ 5 CZ) CZ^ ( ^ 1 CZ^ CZ) ^^ CZ^ CZ^ CZ^ '-Z^ CZ) CZ^ t ^ ) o" o" cT o" o" cT cT o" o" o" cT o" o" o" o" o" o" o" o" o" o" cT cT o" o" cT o" cT o" o" oooooooooooooooooooooooooooo o o r-T co" iT co" co" of co" cT GO" cT co" GO" o T CM" cT GO" *- T co" CM" co" H^ CM" CM" CM" of of cT GO" i>T of CO O^ CO O) O5 CO Ol CO Ol CO O CO CO CO CO O5 Ol HH HH CO CO CO CO CO CO CO CO O1 ~* CO <5 PH PH PH - O JO rH CO CO O Cl t>- t>. CO t>- CO CO O rH JO JO O O CO* JO oj JO JO* l>* t>i CO* *HH CO t^ t^ CO O d O ~-H CO ci OO JO* JO JO' CD l>* CO CO* -H -coco i co><3>o:cs0icsoi< 'So I . CM O CO 5 CO OO Ol ^ OO CO CO Ol HH T^I CO ^ CO ( t>- OO ^O &3 H^OI>-COCOO'^JOCO l Ot>-OC COHHJO^rHrHrH r i ce PQ 03 -Jl . o ^ ^ O O' O "^ O O O O O C>1 Cl Ol JO JO JO JO JO t^ t^ t^ L^ L^ CO CO CO CO O O O OO'O ^"fH-f^ '^ t >^ t> ^ t> - r , rH rN r ~x i -i,'-t > 7 ~i, QO oo oo co cc o^o^o^o^o ^o ^^"^ Co" CO" OO" CO" CO*" r- T r-T IH" of of of of of r-T r-T r-T r-T r-T r-T r-T o OOO OOOOOOOOOOOOOOOOOOOOOOOOO 8OO OOOOOOOOOO'OOOOOOOOOOOOOOO 00 OOOOOOOOOOOOOOOOOOOOOOOOO o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" o" 000 OOOOOOOOOOOOOOOOOOOOOOOOO ~ ~ ~ ~ , ~ - - - - ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ .s ^ ^ ^ ^ ^ co" oo" co" of o ' CM" o" J o" of -tn" co" of o" of co" jo" -rjT of o" co" r-T o" of o" co" of -jT o" 01 Ol Ol ^JH CO CO CO O^J T^ CO Ol CO CO CO Ol Ol CO CO CO Ol Ol CO CO CO Ol CC' CO CO 000 OOOOOOOOOOOOOOOOOOOOOOOOO CO ^ CO CO CO CO rlH CO CO CO ^ CO CO CO ^ CO CO CO CO ^ -JH CO CO CO CO CO CO CO rH CO JO d Ol rH CO CO O Ol CO O Ol rH CO* JO O Ol rH CO CO O CM r-i CO Ci Ol rH 01 CO I O rH 72 FILTRATION EXPERIMENTS. TABLE No. 5. CONCLUDED. Grains of Sulphate of Alumina used per Gallon. 00 HHOCGOGOOOOOCMCMCMCM OOiOiOiOiOiOGOGOGOGO CM Ci GO iO 10 10 Ci Ci CO iO iO OO T7 '/, . X C? OC CO CM GO b* 7! oooooooooo o o 000 c C - O c o^ S&sfS g||p ^||l jig *H iOrHOb~CDbCMCDGCCO GO CO b- rH Ci OO CO co CM 00 r^ GO CO Ci b- rH O CM iO iO iO iO OCb-b-OOOOOOCiCiCiCi b- CD Ci- Ci iO iO Ci Ci IO b- CM Ci Ci Ci CM ~ . o: Ci Ci r. ~ C7 c't . || GO rH CO ^ CM OO CM O HH CM O CM O CDCDb-^HiOCOCDiOHiO S3 CM CD CO CO HH CM HH 10 co o X ~ C ~~ 00 -r co 1 - Bacteria ] Centir In Applied Water. o CD 7T OiOiOiOiOiOOiOiOiO O b- b~ b- O O O O CO O CO OO OO OO GO b- L^ L-^ CO b- O o o L^ CM o C ^.\ CO L^ b- b- t^ b- CO CO CO CO CO GO rH CO CO CO CO CO CO CO CO CO CO CM " I Ti CM CM IO >~ Gallons of Water Filtered per Acre, per 24 Hours. o o oooooooooo oooooooooo OOOOO'OOOOO o o o o O O o o 000 q O r ~ Z Z ; 88 ~. i 8 oooooooooo oooooooooo oooooooooo 88 o o 000 888 c ~ q d - q - q 88 C: C CM CO lOCMHHHHCMOOGOOOGO CM-rHCOCOCOCMCMCOCOCM iO CM CM CO HH fM CO CO O GO CM CO CM ^H -r 7? TJH CO CM C7 GO 'CO CM CO o c? 13. II a g gg^^gg^^gg S s g g ^ pr ^ ^ ^ g :-" ^ PH ^etJPHP-iP-i^^TJPnP^pLi OOOOOOOOOO lOCOCOCOHHCOCOCOCOHH < < PH PH o o CO CO 000 HH CO CO ~ CO TO C iO CO CO CO Ci CM r- 1 CO IO Ci CM rH CO CO O CM rH r 1 CO 10 Ci ^i rH r C7 CO Ci CM i i Ci 00 rH rH fl rH rH cxT cT rH CM FILTRATION EXPERIMENTS. 71 CM iO iO 'O iO iO O' O t> . L^ GO GO GO GO CO GO GO d o' d d o* d d d o* O O 7-1 71 71 CM 71 GO CO GO GC GO Ci Ci CO O O GC GC GO GO GO O iO 'O iO JO O O O *O GO IO Ci CO Ci O GO CO JO JO O CD O CD GO* CO CO CiCiCiCiOCiCi'CiCi _ 71 iO H^ CO -fH iO O CM Ci rH Ci H/f CM 7-1 H^ i ' CO t^ e3 Ci Ci Ci Ci' Ci QO Ci* Cl* GO* Ci' CO* Ci ci GO CO* d CO* I--' ^ O Ci O Ci Ci Ci Ci c: Ci Ci Ci Ci Ci C.' Ci Ci Ci Ci w " alt ter 71. ree lied CM CM co TO co cc CM CM CM J 7-1 HH O HH 71 IO ^D O O HH t^ O ^r 10 CO O HH O HH 7-1 CO CO CO iO CO CO HH CO i ' CO GC CO CM 71 O L^ ii rH rH T ! 1 88 CM 71 X 71 71 O 71 X 71 O CO o co 7^ -^ CO CO -2 T3 71 O iO iO JO iO O) O> 'O' 'O' 'O C^ ^O* O^ t^* 7^1 CM 7-1 7^1 O O O O O O O 1 O O O O O O ^D L^ L^ L^ O c T 1 1 *o 10 ^H HH HH iO iO *O IO CO CO CO CO CO O O 1 O l>- rH i i 1 - o O 8 O 5 8 q 88 O O 8^0* ^O 'O* O 5 'O' ^O O^ CD O^ CD CD CD ooooooooo ooo ooooooooooooo c O O O o o 88 O ^ c o o c 8 O 88 8 O ooooooooooooo ooooooooooooo ooooooooooooo x 1 88 CO CO 71 -r 71 C7 71 C7 ~ eg IO CM CM CO CO GC GO GO .GO CO IO J-O GO rH GC' GO IO GO CM 71 73 CM 71 CM CM 7 "H. 2 % !1 One-ha One-hal 10 FILTRATION EXPERIMENTS. fc H J PQ ^ El x ^ S *4O IS ollj s^ t^ rH CO O O ;O ^^ ^ O CM tO OO GO CM OO O OS b- CO O Ct L^ S CO OC 00 1 nit S|S O 00 O r^ O O O O O K O^J B % ^"S,'C P CM s ?^5^ Ci ' :o" JtS ^-^ ' ' C-H. ^S^ml PH"^ " . 1^1! CM t- i 1 CO O 'CO rH M CO rH CO JO OO t^ O "* ^ PSI Ci OO CO o o d CO OO C5 rH CO Ci Oi O O5 Ol "3 ddd^s -t-i ; ^ o >er Cubic leter. In Filtered Water. O CM rH O 00 CO CO ^ CO "HH CM CO CO rH -fl O i i rH CO CM S co co o O 00 rH 00 00 CM CM " L-- CO *"~ ~2 .5 : C6 i r C : n3 l !|S ^ ; &"* iO 'O O C5 t> O 80 O O O O iO O O t^ CO ^ rH CO | 00 GO 00 O JO O CO O L- CO JO O ^ O 'O GO o <<> 1 if t^ co rH rH t>- > l -H^ CO rH S rH rH O O 3 1 & *!i. 8S O O O O O O O 00000 88 O 0000 o> I O ) o^ o^ 00000 ll |S| O 00000 (^ 0000 . O 888 o o o o o o o o o o 00000 r 1 o||* r-i O CO' CO rH rH CO CO CO CM -HH O rH -J O O CM OO Ci CO CM CM Ci GO OO OO rH rH Ci CM CM ^ |l ll i i _i rri rr> - ; r^,-i <-n ^ _J f'; , 1 t \ f**, 1 \ f~\ , ^ rH OO OO -to (M GO 71 rH rH rH CM rH T IOOOOOOO fMCOCOCOCOCOCOCO Cb i CO * r-l CM CM - o s ^ ^ FILTRATION EXPERIMENTS. ** C' O-l O X X 00 00 O iO O O O rH O O' H r- IT I O3 ^-H X OO O5 CO oooooooooo O 0-1 CC rH C5 CO CC> X IO O' iO iO O O O r^ O O s^ is ::::: I l O i o* co i o I 0) <=5 is 05 jj-g : I| C L _gS O iO CO -HH CO CO CO iO X GO CO X rH O Cl CO b O CO O iO CO "^"^ oSciC^OO sOOOXOC^COCOOC^OiOCO ^ C5 C5 OS O O GO 'S 0> 51 O " E? -Gft o SI 01 co 'CO O 52 co Oi O ^ co co co O -H o-l CO C-l HH ^ co -HH co b- co O-l OH OOOl'O CO ^ IO CO O O O r * O IO CO O- O OO rH . CO ^ CO b~ b^ rH CO Ol O3 O-l **H ^ rH rH rH rH rH OO CO G<1 rH OO CO O ^ rH rH Ol Q2 U g _ I _ O iO iO O O *' O iO O iO CO O iO iO O b O O CO ^ iO O O b- O O b Ol b O O 'C O OJ O b- CO O b- L^- O CO O O CO 'C O-l O O CO O O CO O b~ b- O ^ -^ b- rH OO CO CO b" CO OO b G>1 OQ r I 2 O 'CO b^ IO rH O O rH k rH Soooo ooooooooooooo oooooo oooo ooooooooooooo oooooo ooooo ooooooooooooo^ o^o^oo^oo^ -g o'o'o'o'o" o~o~o~o"cro~o"o~o~o~oTo s or o"o"o"o"o"o" S ooooo ooooooooooooo oooooo w O^ 0^0^ 0^0^ O^O^O^G^G^O^O^C^OJO^O^G^O^ O^O^O^O^O^O^ ' CO*^ -rfT -CO*^ b-^ O"T oo" ^H^ -rjT QO~ *^ '"H CO r- T OO iO HH CO X X X 1 X X CO-fCOCOCO COO3OlCOG fjl 1 "^ , T? 1 ^H *"* O*^_J O o^ ' ^sO r [> s "^ ^* S c: ! ' - ^-. ! CX; *fo r -Jf^ ^ O (Tj --n ^ 1 ^ ^ | 5 f % ^ "^ ' foil's O CO CO t^ r-l O 1 1 OtOCMtOOCt>.^OO i^lil o CO CO OO' Ci ^ CO c: c: cr. o o n o 'Si * J w *' w " ^ ^ 111 O g <0 )er Cubic neter. In Filtered Water. s Ci t^ CO T^ CM -^ CM O CM iO O OO OO iO CO i 1 CM 1 ScOCOOOOOi ICM^H PQ to rH^^ CM CM * CO CM p ^ ^ S d Hi iO O CO O O O O t^ O" CO to O O tO r-i L^ OO O -rH TF 'CO 'gooootootoo gOOCOtoCi-^OCOOO o H ^ ^ ! 1^ ^ CO Ci O Ci CO CO g 1 1 6 J g li 'C! ^ O 0000000 0- oooooooo oooooooo 0^0^ 0^0^ 0^0^ H l> ^ S ~c OQ IS1 1 o o o o o o o 8000000 O O O O O' O 0000000 o o o o o o o oooooooo H ^ ^ C"i o3^ T 1 CO O CO O CO CD CM HI T 1 1 1 O T-l 1 1 O O OCMOOCMOOOOOQO CtCOCMr- (T IC1CMCM PH ^^ ^ 1 ^ QQ O Minutes after Flow. o i 1 00 00 CO CM OO to CM r 1 T 1 r 1 CM i 1 i I i-iOOOOOOO CMCOCOCOCOCOCOCO J Ex ^"H ^ s g ^ H 5 ^2 L^j rN ET^ s ^**^ w c H p CO Ci CO '^f T 1 1 i-H r< 1 ^ * t^ t- O CM CO -# T 1 rH CM CO T I o ^ CO -^ i 1 CM * t>. ,-TCM CM CM fa Q *~s FILTRATION EXPERIMENTS. 77 rH O CM O CO CC> CO CO O iO i^SSSSSSSSSSg O CM OO i 1 Ci GO CO GO O O *O 1O rH OOOOOOOOOOOOO O O O rH O O -J j- | Oj o' : : : .^ Ci s ! '. ! ! c: 0: sl 1^ C^ t> C^l tr^* Oi ^oco-ooocccooo^^o GO rH rH CM CO Oi p CM CO O GO CO o: Ci c: co oo | CICiOGOOOGOOCiOiCiOO s 'o C5 C5 C^ C5 Ci GO .2 If grain rature of CM CO CM OO rH rH rH CM ^ rH rH 3 03 O ,0 GO GO CO O CO GO .-S CO O CO rfH O C^ ^ rH rH rH O> P3 Q? O *O O O iO o t> CM o t> O CM Ci -HH CO -2 0000010*0000000 IB GOGOt^COCOCiCOrHiOrH'COCOCO 0^ 3 o 10 o 10 10 o . (^j ^J 1O t>* I>* C^> rH CM CO GO iO rH CM CM rH rH CM c rH CM rH T i CM CO CM a ^ CM CM r^l rH rH rH ^ o o o o o So o o o O O ooooooooooooo S<^> o> O^ O^ O^ ^O <^> C^ ^O ^O OD CO rH CO CO CO w" S" 53 co S" S 5? S" ef w" S w" S OO OO GO CM GO CO CM CM CM CO CM CM w g o o o o o CO CO CO CO CO ooooooooooooo CO CO CO CO CO CO CO CO CO CO CO CO CO O O O O O CO CO CO CO CO CO made by Profes c~ > ^ * P3 |^!* o *^ "r^ "* S **^ rH O5 v- ^ ^ ~ ^. 8 C3 1 - C5 O fl V. - - - f3v,^x>^^v>^^^v.^v. r^ ^ r?" 78 FILTRATION EXPERIMENTS. ^ j w ^ a o d ft? SB'S? C 3 3 15 GGTS OOOOOOOOiHiHOOOO b- CO CO O CO i-H CO O CO O C: CO 00 rH -H co'oc^cdco'co'cocirHHcO'-^rHcoco PH ^. Cs **N *to CT^ 1 *' ^ CS PH -S 3 % .2 S-H (M O CX- i-H CO CO -H CO -H O O ^ rM CO >O -t< CO :o CO i i -H cq Ol CO i t O CM (M -tl Co t>. T * c O 88 - i O o o o C z II O to o ^g b- CO CO C7 b- b- rH I - II ^ -H rH ^1 O^l CM CO CO %i 3 8 E q 88 O 88 ~ 3 888 000 r z C^) CD C~^i C^> O o o s B 2 Q O i ~ O O S8 5 888 O c c ~ o o 88 el B^ CO T 1 ~ o T^H CO O "- O CM CM CM co ^f O O C5 ^ 1) D R o 1 1 CM ir i-H b- CO i 1 rH O CO rH i 1 CO 1 1 CM CO CO CM rH CM - i CM CO CO rH CM iO CO t 1 rH pt I Oi 00 o * ^ CM CM CM CM CO ^ CO^ " of* rH O rH rH 1 o o X FILTRATION EXPERIMENTS. 79 o *-< O O c: t^ TtH O - 1 o co o c: o -H -co i i CM CM o -H CM 10 -H o CM o co CO V^ ^ C^ iO ~ L^ ^ O O O ^ O ^ I>- JO O t^ CO 00 CO GO GO GO CO CO O tO o'o'd d d o" d d d d d d d d d d d d d d d d d d d d r-i" d i :~|s !:!:::: ': ':':':':': ': ': !!::!!!! i^ : :S ! g : ::::::: : : : : : : : : ::: ; : : : :S?g I - -* Tl 5 O CM 'O >O CO O t>- tC 1 lO* j o' "T^ O CM *O *O 1O O CMCML^-T-HCO-^iHOCi cc .Sf O CO O ^3 O CO O O OO OO T ( O^l rt< rH "^H ^H ^ O t> CO OO O OO OO -rH CM O ^O O CO r- (CO ^iOTi'-HCMCMT i^ rH, IG\li (CM-^T IT ICMCMT Ib'COCOCMCMCM^t 1 ** 5 O T I ^ O C^O^C^ g OO^O^CO^O^^CO^O^^CO^C^C^C^CO^O^O^CO^L^ O -S G T I I 02 . 1 ! 000000 OOOOOOOOOOOOOOOOOOO ooooooooooooooooooooooooo O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O^O O O O O O 0^ o~ - OO GO o o o o o o o o c o o o o O GO GO rH Ci 00 CD OO *O O *O *O O C O "-J O d O || 5s 1! Minutes fter Flow. COCOCOiOGOGOCDOO O Ci CD GO O Ci CO CO rH Ci CO CO CD CO l>- CiCiGOCiCiCDOOCiCiCiCiGO t>. O CO O *O CD CD* CD' t>* ci L-^* - CD CO JOCOOCiOi-HCiiOCOCiOOOi i i!CDH- | OOt>.t>.i-H rHrHr-l rHrHG-lCOG-lrHCOCOlO rHrHCO 1 ~ I ~ O iO O >O CO O 1 O 1 OOt > OOCO tCiOOOt^-^O OGOOl>-COOL--t^OCDOOCO ^GOOOCDOO H^t^rHOOCD^CDt^COOOt^CO^CO^r-^ S O^CD^t^ O rH^ O^ Co"r-Tco" r-Trn" Co" Co" Go" icT H" H^ "m io" CO*" cT t>T CO* Co' rH J 33 i I ooooooooooooo oooooo 000000000000 oo o o o o O O^ O^ O^ O^ O^ O^ O^ 'O__ O^ O^ O^ O^O^O^O^O O ooooooooooooo oooooo oooooooooooo o oooooo o, o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ o^ c ^ G-f Go"T-rHH"GO' > HrHH* > Co'"^G^io' N HH r> GO' < GO" GO" GO*" GO*" GO*" GO" COCOGOCOCOCOCOrHGOCOGOCOGO GOCOCOCOGOGO ooooooooooooo oooooo cococococococococococococo cocococococo Cix>s.v^v.^v-^^v.^-. Ci^x^v.^^ ^^v.^v.^x,^^^^^^ QQ^^^^V, rH rH o v o"i-rco"co"o r "cD'"t->roo' v cro'~Go' N co' s nTo'5o't>rcrcr rHrHrHrHrHrHrHrHr-COCOCl GOGOCOGIGOCO ^^-s*^^^^S*^*S*S*V^ ^SJV-s*S*^ FILTRATION EXPERIMENTS. 81 PQ ^ ^ "O "**vj ^ s 1 r^ ^ QJ rO o ~S -S ^ & ^ ?-> ^ =: O ^> ^ s C3 S TS ^ '2 O O l I ^ 15 ^ cw . o s ^ O ~ lO eg !i f I *-5o O<5 BgE I number i 1 number CO Q s'g number 1 S S a o ^ i ad > D ^ >- S H^ S D o ^ 3 * < ^ ^ 3 GO rH ^ D ^ CM r ~] N O "w ^ 3 _j ^J fi co~ CO 3 CP n^ CM t? O ^"S B C t- H (H Cd 2 S s a C^ *~^ -5 c H *~5 Q => CO :- &H 3 05 CM || li c ' s 5 0) C3 S 5 < FILTRATION EXPERIMENTS. 83 ^!i ?S ^ ^ s OQ 2 ^ 02 B 00 iO O ^3 HH ^ Lrf ILi ^ l numbe O5 05 numbe C5 numbe HI 5 W c3 a3 2 B 1 1 1 o ^J CO i i 06 I I o| 5^ | a O5 i 05 a a ^ o~ g 2^ o -*j g 1 "o EH 00 \ 52 3 2 o number 05 number O V3 05 number O oi 05 'c '3 1 3 fl I o EH 1 d 03 OQ u CO 1 r^ O5 M "a 00 O 'Sb ^ | 1 1 00 ;g r-H H P4 | s of ^ CO | la g 1 & c8 " 1 rH O | co" CO O rH O5 "^ co" CO s 1 o o ^ 84 FILTRATION EXPERIMENTS. l! 2 CO g S s | number i i number li number 11 number ll 11 1 | 1 -2 * 4a CO OS co O CO CO X2 . t-< (4 J^ ^ 03 GO JS o> ,0 x & o| Jo a s c CO o g 3 fl i I a s '0 CO r^ a Es* "3 "d "3 'cS E o 1 I g 1 ft CO so . CO - ft 1 i o ,0 I i ^ p a C( ^ S a l ^~. QO a ^\ ^* a 1 ^ QO* j o o o i CO O ^ ^ C5 S 5 a CO g ft fl 3 "S 3 i o e 1 g g o . 'S .' o O CO : fl o H r^ 00 O ~ ! ^ i^r * H L ^ \ 'o i-H - CO O "oQ rH -+l r-( O ^ . 00 00 M o > rH O - S f CO .s o ^ C5 55 S "^ rH oo rH CJ -* -2 T 1 cT S ^rg O ^ co" CO "* 3 O CQ d ce d eg J II H^ o 3 *o t S "* S) bo o 05 (M & S " d c d cS 1 1 FILTRATION EXPERIMENTS. 5 2 1 ! 5 CH ^g co v rO -^H tl ? B5 5 O O rO "" ^ 1 ^ ^^ S "8 o o o 3 ^r-j O Ci GO S t* 05 S Fj " * a .5 CO o i I a o o (H ^ g KO ! 1 1 8*g s a ^ gw la "o fe^ ^'a ^o 0> ^3 ^^ gg 1 35 0> J3 g ^ w s |a O .0 *-" s-t o a o3 l L^ l^ rH 1-5 O If VI i 1 o : 2 g ^ S o3 zi g g 03 ha JS O 3 q a 93 (3 'S "o 1 1 ^ S * II CM CM ; rh 03 co" 02 jzj 1 s 1 i 1- CO CO r^- S S -^ * (^ ^ 8 H ' T-H o *j ^ (2 03 0> o a o "p, "S g o a 1 o 2 1 o ^ 05 - 1 p g & |a T-H T 1 g O ^ | II o 1 02 o fl 0} ^ o i Per cent. Total. 1C CO oi o i GO CO T ( J8 ^ O g 03 ( ^ CO a - js Pi a o EH OJ 01 l IB CM i i ; CO CO ^ 1 w o CO ^H *O OD ._ S 1 H FILTRATION EXPERIMENTS. l| ^^ c^-* r^i r~+^ ^* menced 1 o m " S O n Ci Ci O5 i 1 1^ a o E-. || a r k. &3 r- ^ _CD iT3 03 g o S |S S c8 "SW > 13 o ^o | || *=! 3 r CJ < 1 1 ll GO T-I GO | ft^ bq ga 03 j |i g f c K ^ ^ i 'i ^ ^ i 8 gg o 1 S 1 "^ ^ K $ , d c3 2 II oj z> S . It t>* CO t> " co' co' co' '. CO > CD S^ On 10 -vo -rT^ ^ &Q Q g ^ ^ o o ^ "0 PH 2 o g B ^ "^^ ^^ - XJ g 1 1 * | T t 1 ^ 1 11 s te < ^ ?l 1 |l H S s & "i 1 ew -o gs^ fi 1 1O CO CO r 1 r^ ^ * * to Q; -^ GO' co co' '. o '"** ^ ^* ,0 & 02 $ i- rH U H GO CD ^ co (D CD Q^ ^ ^^ P^i- C^ ^2 fe Ci ^ PH S .- "2 03 jH 2 S a "-S |r S> ? CD 3 O OS ^ H CH ~S 03 OJ ^ t* 1^ ^ ^. ^ "S ^ ^ i w ^ "o 05 S * ^i (^ S ^ "s g. GO i-l rH "* IS r-i O ^ 3 P^ 1 ^ ^ . l^ CQ ^ 5 S L. S '" 5 r< /C ^ ~o a 03 (^ S) , h^j 03 O r-C^ Wj ^ ^- ^^ -to j^ f*3 03 3 ~>s ^ ^r^ r< 05 ^ T-f GO CO ^ 03 ,| ^ JT H 3 Q .0 fej O 03 ^ ^ r> ^ ?> c^ ^ O ^ Q f H FILTRATION EXPERIMENTS. 87 fc; g O ^ ^ 3 ^S S " r-ii -+-^ GQ tx ^ ^ . O , o rO Q C5 ^> s % S3 *Z <** *^l s p S co ^ ^ - cc; 'S ^ ^ ^ I -S ~2 .o o ^ ^ i I I > . O 'J 1 I ^ Oi V a oj 55 II o : o' 111 1 n^ PH I wo& a e8 Qt'2 if . H J 3 O IH < . -2 * Si 1 || rv, CM *c3 ^ > 2j 5 g 2 g a 1 ^ 'cS o . O % o QJ ^} j 3. EH I s CM off 3, I O CO CO d P, w o o3 ^ * CO cr^ i - g ^ g, a ^0 3. c3 c^ I O ^ -3 o - 2 o +3 O EH jl : - rH o 01 CS ^! O I || o I "^^ CO CO * 02 t> eg -*^ o i CO 1 I a i f fl 2 So a 8 o g CJ 3 -d | t-t ' o s 3. a oS H ^ 1 S II |EH T 1 \ i i | 02 ^ ll CO T^ GC i H 3 P5 r o 88 FILTRATION EXPERIMENTS. ^ f^ ^ \ <0 ^ fa o ^ g is O "^ ^ *" 5J? 2 & "elS CO L^ i 1 GO CO CO CO -CO CO CO -CO CO ^H ^"" >ij ^) i ^O O ~ (V | \Z* 2 ^ I "ooB o3 p 0. C-l -t^ CO O rH C-l 1 1 O O O O O O < QS 5 *- s5, g "s H fe ^ I* : S*g 1 ? c"> c _ o ^ S 1 1 |S LSI^ _o 11 CO O -HH rH Cl 'CO C-l rH i 1 rH rH rH CO 9 ^ ?! ^ f! r H IP N 5 s^ \ |5 .5 ^ ^ ^ ?, 2 fl ; ( O ^ vX) ^ [>j s; aJ a' m ao - c % % *3 I w ^ 1 Number Times rH CO rH | C^ rH \ rH ] 08 ^ l^j ^ O 5 o u r^* t^i O ^ s" " S QQ s rO i o ^ ^ -S S a o %i ^ o c ~ ^ ^J ^^ j" ^ CH ^ ^ s : s O "^ O ! 3< g 2 ^ ; 1 fH GJ o > 'S " . ^ r-^ ^s ^ (^ r**+* 0) EH ^g rH ' rH CO Q3 ^. "t"^ 1 CO ,3 g-S p^ ^ ^- ^ *^ g SH "S ^ ^ -^ 9 h - ^ 0) O ^ <4) s 1 h. ^ = cS g ^ ^ Qi q^ O Q*J ^^ ^) -^) CO r* - ^ (^j '^~^' cS . g| CM ) CO **o ^ ^) ^i * r^ GO 1/2 t-N* * S . CO . . rH r^ si '""H [^j - 10 f 2 d a a* % % ? ?n I I ^ ^> "* Jf ~^> ^}. 0> r^ O G S r^ ^2 d ^ h o c 2 -TO rHCOCO^OOOOC}O*OClCO Qfl ill ll \ w w a a ii rH rH C5 |^ o"! 'A FILTRATION EXPERIMENTS. 89 s 0,3 *; o_E' 25 lrh o o ^ S . ill I CM i I CM CO II I ! HH II ^3 _; 5 fe c 5 ! ^ 1 8,1 3 ^ gi I 'S > I la rg tH r* f**o ^ ^ &H to ^ Pa a~ "^ g^>^ ^"1 ^ UQ S 4J ^ Cj 1^ ^ P,, ^ J"-3 to ^ ^ O ^H P^ ^ fe ^ O .5 l^i S | ^ ^ ^ O 1 to ^ -^ 8 [I I 3 g 5 ^^ | "tS >5 -w Os ^ "S <> . rH 1 B o 1 o ^1 -f H^ l^ b~ L^ CO -d H cS >out 90 II CO (-, 8^ H O PH 1C C 1C L^ L^ .1^ r-l rH rH ... o o 8 13 Growths of at d a I Number of Times. (M aq rM rH I 1 r-l o: O ft o "o i 1 T 1 ' L->- t>- t->- CO I- i Cfi A I P CO 1 1 CO CO , . t^ b- L^ GO Ol . . ... oi cc t o 3 H S3 fl I Number of Times. CO CO rH T rH Oi n z; 3 i W ..... GC la +-> CO'^iCOb'.ODOCO^b- rH rH rH CO o EH FILTRATION EXPERIMENTS. 91 fe) c ^ S S ^c J^i Co rS ^ $38J 1 o CM co co co hr CO 1 fl I I I g Growths of at Averaj fl I Number of Times. T-H rH rH [ j rH \ ^ o K* t^ t~ 2 ~ 1 : co 1 I 1 II I I CO H ^ 3 I Number of Times. I I rH rH rH | ) CO j ; 5 1 } . i 1 ! 4 = I H s 1 . c J i i u I.I.I.! 1 o H r^ C^l CO ^O tr** ^D G^ 92 FILTRATION EXPERIMENTS. 9 H " 1 o CO CM (M -CM qs : | .O a 5 s o c" e3 O s Growths of 85 and End Averaj 3 "3 1 Number of Times. CM 11 T 1 | i 1 o a 3 o "S g-3 *...*.. ^ 1 2 CO 1 P : : : 10 T I 1 o3 Growths of al Avera a o EH Number of Times. 11 '. ! rH ! CM ^O -2 o t>. t> t^ T-H i <' i-i I CO 1 jji : ' CO CM O g a 3 1 Number of Times. - ^ - i i CO . ft x : : : < EL E- f n E. : : : i : I 1 . p p. : ' : 1 CO 10 t> O CM T-H CM H FILTRATION EXPERIMENTS. - C) O QQ Q) o TI r^ J 5 o^^^ CO Q r< ^Jfe -HJ V^ C i 1 ^ ? 2? N <* ^ o, 1* WO&i 1T3 &' III .- ; I o i '8 ^ : . -i : * g i ^ rf ILg * 1 " 2 en' PH O 22 t > 5 5 1 I a 6 5 o Av Numb Tim Numbe Time O O . oo , I co o si mbe ime 94 FILTRATION EXPERIMENTS. o H O tN t^ t^ t^ ^ gj I!! CO m m & s 1 i t^ I l> . .* t-* CO G^ Growths of 85 and End Averaj i Number of Times. l-H \ < H T I CO I | o o S'S t> !> t> l> GO SJ 1 K o s s 2 co ! I 1 . t> t> t> t> CO 05 pa o3 HS | Growths of at Averaj P 1 Number of Times. \ T 1 T 1 1 1 1 I ) T}H 1 ^ * 8 S CO 1 Per cent, of Total. t^ ' b- ' ' t>. L^ ! !>* ! '. t^. T 1 CO (^J ? d ^ s ^ 3 S3 'S 1 Number of Times. i 1 ) T I | | rH CO i : * : : ' w o . I j I I ! B W . < B EH S . E- oc I :::*:: g (z p C . Pi P. 00 3 . H ?H CM CO t>. OO O^ CM FILTRATION EXPERIMENTS. 95 fcx PH ^ H ^H H PH A f*4 s HANIC ^ o o^ H o s ^b N o o & CH o d HH ftj ^ c '"H H g PQ [MENTS.- B AC ILL pq X3 w PH < 1 o M ^ PH 1 H -K> A o^ Jg s'S ocr.occoooocr. oo .00 -d %5 11 OOOOOOOOO 00 O OOOOOOOOO 00 '00 vg - Qi imeter in Fil h obtained. Hours of Growth. O fM . O CO t^ t- t- . . . -HH -HI O 1 . 1 rH r-i O rHrH i t T 1 rH rH ... ^ g o r-^I > oi ^ (H ^ 1 rH 1 ^ o 'o ^ g> o ^^ ^ 5^ **o ^ * s ^ <> r- H ~ -- 2 & ^'S " ~~ . 1 r< 22 a o E3 O ? a 5r5 o -^ O 1J J % 1 <5i C?5 a 5 M< ^ ^ ^^ ^ r< r-o 10 "5 H I o" i \ s ^ w i% CO 5> r>^) S3 c8 O ^ ^^ ^_ S rO ^ g & rH ^ fill. D OOOOOOOOO OOOOO 2 r^H cJ ! ; > ooooooooo ooooo 42 1 ^f !' 5 SSSS^^cocoS co^co~5 10 ^ S -g d ggg ggggg ggg 1 |j| SOO^MOOOOCO *C<1 O O O G^ OOrHOOO^^H -HHOOOrH S K ^ ClOrH rHC^COCOlO GOOOrH rH i 1 rH r- 1 rO DATE. CO CO CO Oi Ot> Ot> GO GO 00 1 T 1 rH co~ ^ -jT C"l CM G c^> O> O> ( ^ ) *^ ) O> < O ) b- O CJ O O O O Cl o o o o o o o c? J3 '. J3 C CS a I s : 2 S il ! s g, "> . CM ... CO 5 so . . . Oi . . . ...O O o ^ o ^ H^ I -t S-g I .8 .o 33, |s : : : : : : : : cr '. '. '. ' '.'.* ao p, =*-, O .2 '^ 1 O O O O i t O O ^ COCOCOCOCOCOCO^H/l W ^ rH CM CO CO ^H O O* rH CM* CO CO CJ O* rH CM* rH CM* CO ^H CO os GO CO CO FILTRATION EXPERIMENTS. o q -X' q q q q q q q q q q q q o> q . q o q q q q o o o C: O ci O O O* O O' O O O' O' O* O' O O O O O O O O O O O O CiOCiOOOO OOOOOOO OOO O O O O OOOOO ' ' S -^ c: O CO OO OO CO CO 00 OO 3? 4fn ' ' Oi r- i * ' i CO CO . ^i o si ooooooo 01 o T i T i ' co o . . r?q . .... ... O Cl O JO O 5 iQ Ci CM JO O iO CO O ... <^ .... . . . q, . C5 ' 1 I 000000 ooooooo oooooooo ooooo oooooo ooooooo oooooooo ooooo OOOOOOO O OOO'OOO OOOOOOOO O O O O O 80 o"o o^o^o ooooooo oooooooo ooooo oooooo ooooooo oooooooo ooooo (^) (^) <^> ^) /^i (^> (^) (^; (^> (^> c*^ C^ ^O C^ (^> C^) (^) C^ <^> (^) t^ 1 <^) (^) C^) O> C^^ l ^ > ^O O) C^ C"l GO T^ G^l OD *O ^O OO *O ^O ^O CO ^O OO OO GO OO *O *O "^ GO ^O *O *O CO ^ CO CO (N CO CO GO G<1 CM (M Ol (M f>l l C T 1 sj a1 O O O O O (^ $ p< 1 g 8 80 88 o o o o o o o o O Q CO OS 00 rH C. O O C2 Ci O O O O O O O O O 8* O O O O O* O O O O O* O O ci O C5 c: ci O O O O O O* O O O OOO OOOOOOOO OOSOOlOSOiOO OOOOOOO CO CO CO b~ b- tl ,__( r _ l CO CO t^ t^ b- t^ c; c: b~ co COCOCO CO -X) 00 CO ( c 10 c *o co co co O O O O O OOO O C: O CO CO OO OO rH rH r-l l> rH GO OOOO 000 OOO OOO o o o OOOOO OOO oooo o ooo o o o oooo OOOOOOOO OOOOOOO ; oo OO OO oo OO c o ooo O OOOOO o ooooo COCOCOCO COCOCOCOCOCMCOCO COCOCOCOCOCOCOCO COCOCOCO(MCOG<1 & g s a a a a a a a a a a a a . a a a a a a a a a a a P4 On' fin* CO O O rH CO O rH r- C< CO CO O O rH Ol rH G O Q} t3 o o o o o O O O 0' O O 1 1ft P o o 88 O O o o 0> S-. O> PH a "8 1 !i O CO 1O CI 00 T i 10 o iO O O go O Ci o o Ci' Ci ^ 00 o o o o o O i-H Ci i 1 -o o 1C O CM ~ti 1 o O | 1 | ft I ^- ^ M o t; ^ rh 1 c = 5,3 g r- S * p r,3 H """" w ^0 g .^ 5 H ?H ^ 6 2 ~~> O O tJ ll C * ci T 1 i o . 8 . 6 ift So, s' 2 * cr CM .9*1 ~ 3 PR o ft o r 1 j PQ w S ^^ i ^ ^ "So r~* ^ SE pH o B w^' C - CO Ol H^ rH rH '.'.'.'.', !!!!!!!! ! co !!!!!! ! ! '. ! O O 00 o o o o CD < ^> O*> O) . oo ... I ! ! c> ' I ! I i ! ! .' ! co oo OOOOO O O O O O O O O O O O O O O O O O O O O O O> (^ *^) ( ^ ) ^O (^ <^> (^ -* R S3 *< !> " -2 P C rH rH t>. rH -HH O CO O rH CO ^ ^S COGOCOGOCO COt^Oib- 1 1 ** .5 ,c o si 1 1 653 o | IS s 5 3 *- ' ' -TJH CO ^ 1C rH P, - ! ^ 5 ' 5 8 .2 5e 1 I o S ^ ^'3 - <* .73 W W ! OQ . -^ 03 > a ^ so cc 1 * tfl O * * * 11 o ^^ s-g J . o . . . o 1C (~} (^) . o . . . o a c fe . ^ . . . 10 O CO V "* s3 & Is 3 -1 1^ 5 Ho S SE o .t: m sll. O O O o o o o o O O 0000 O O OOOOO OOOO OD '^> <^> <^> c^j (^) <^> O) CT^) C^ gs3 > <^> o^ o^ o^ ^^ SO> (^) O) ^^ o o o o O O 0000 oooo OOOO OOOO OOOOO OOOO olfe^ CO CO ZO CO O ^H CO CO CO CO CO O GO O CO CO CO CO CO O CO O OO t>- CO CO O CO CO CO CO CM ~*COCOCO ^ ts a g g g g s s s ggggg gggg || <^ PM PH PH cO . rH CO CO O . CO OO GO GO -* CO CO CO CO rH rH CO t>- rH GO 00 -GO 00 CO CO CO -^ O O O "<*i rH CO co- CO O CO . GO . co CM GO O O O Ci CM GO Ci CO CO rt< o o o CO CO CO ' .... . . 1 c - I < Q H O 1 (Li P. CO CO bX a "a "o i 1 * Before Prodigiosus solution was turned on. t Temperature of Applied Water 71. " L " CM : : : : : ^^ O 8 8 . . 8 . o . . . 8 CM o . o rH O O O O 000 888 O 888 O O O O O O 8888 0000 00000 o o o o o 00000 000 o o o 000 O 0000 o o o o O 888 O o o o o 8888 (M !>. l>- CO OO HH CO CO CO CM 00 GO HH T^ TH CO (M CO CO CO CO O CM O *O CO CO CO CO CM co OO (M HH CO CO CM O 00 00 a a a a a a a a a a a a a a a a a a a a a a a 4 PH PH PH | O O O CO CO CO HH CO ^ -5 i- CO QO rH o3 CO OO i H CO CO GO GO rH rH d d HH CO GO r ( GO rH GO" c d 104 FILTRATION EXPERIMENTS. c H Q P H! o ! CS O fc l-i *tS ^ 5 ^ U i ~ ! <^ o p I O O O O O O O O O O O O O O O c c r- g S O O . O 000 CO CO CO CO CO(MTrOCOG5r-"COCMO5rH- 'O >O O 10 tO tO to 'O oo'ooorHOoooooo'oo'o tO CO 1-1 i I |o j : : & 'E ^ fe : : : SH <, a ^ g I o |Q 1^ O t. 1 1 X & s| 10 co s : : : : TS ^ d o s ^ I ; ; 1^1 tit ^^ I r^ ^-\ "to 3 o- .^ ^H cc w , 1>- S CM S . 11.1 to ep . O^^ l|l I d CO g nH | CM S f ^ a =2 1 : : : : ill I I" 1 1 i r*> ^> p*-^ *> **to C> ^ ^ aj : II 3 T3 . % . dp 11 i i o s GO S o GO i; CO 5 08 i CM 8 ?* ^"*S ^~^ fen s '' -to CS n' C ^ ^ is 11, ^ -S ^0 E| S ^ 5 - *0 ^ 02 S-T *J 0) Is is 2g Sg . 5; . 58 o S ^ lo i ft | S CM " d ^ 1^*0* o "o i 2 ^ 1 .2'-^ t: o ^ o N j ^ ^ X i ; ; o ^ ^ f ^^Is CO ^ CO ^ CM* S S C .B O'd^ i i r i : : : co &} o" ^ 1 'g 1 ( ^ S o S | ! ^ 3 | ,2 i S s s ^ ^ <1 b p K * Q EH ^a ~5 "^ 1 1 100 FILTRATION EXPERIMENTS. CO O O CO l ue. co g O 8 GO o co CO eo O LO CO CO CO CO o > CO o CO J^ CO CO FILTRATION EXPERIMENTS. 107 TABLE No. 20. CONCLUDED. Sample of Pawtuxet River Water taken at Pettaconset Pumping Station, May 20, 1893, at 7 A.M. Parts by weight, per million of water. by weight. Sand and insoluble in acid : . . , 2.81 Oxide of iron, Fe 2 O 3 65 Oxide of aluminum, A1 2 O 3 .48 Lime, CaO 2.89 Magnesia, Mg O .68 Potash, Ko O 1.33 Soda, Na 2 "O 1 . 53 Sulphur trioxide, S O 3 1 . 83 Nitrogen pentoxide, N 2 O 5 1 . 15 Carbon dioxide, C O 2 , to form normal carbonate 2.36 Chlorine, Cl 2.52 18.23 Subtract oxygen equivalent to chlorine found .56 17.67 Unaccounted for . . .45 Amount found independently as total mineral matter. . . 18.12 Carbon dioxide, expelled from water by boiling, 3.02. The Above Results computed into the form of compounds. ] Sand and insoluble in acid Parts by weight, 3er million of water, by weight. 2.81 Common salt, Na Cl 2 89 Potassium sulphate, K 2 SO 4 2 46 Calcium chloride, Ca C1 2 1 . 20 Calcium sulphate, Ca SO 4 1.19 Calcium nitrate, Ca(NO 3 ) 2 1 75 Calcium carbonate, CaCO 3 2 14 Magnesium carbonate, MgCO 3 1 43 Ferric oxide, Fe 2 O 3 65 Aluminic oxide, A1 2 O 3 .48 Carbon dioxide, CO 2 , combined, but in excess 67 Solid residue, unaccounted for ... 17.67 45 Mineral residue, found bv test. . 18.12 Carbon dioxide, expelled from water by boiling, 3.02. 108 FILTRATION EXPERIMENTS. . d > ' :::::: ^ ^^ ^ i .2 ^ i a ^ |l .. ; . o t>. CM CO rH CM CM C > CO CO rJH O . CM CO ^ ts-g : p^ "fH d^ t> <^j M) 03* : i ^ s 11 *I g s v> t**" tt S- 1 S ^o ' ^ ' fa & ^ t> O : ^ ' S-i ?R ^ i S^ M ^ r->*> ^ J -Tflt>. CM O*O rH CM O ^ t ( >| iJ -3 CO rH O O rH O C <5 S3 Q JrHOrHrH rH CMrH fc PH c *- (^) j: ] "c o> ^ ^ fee : w 1 ^ . . O P5 cc ^ H l| . : gc % CO H ^S 3 | rH rH C * o o > O O O CM O . rH PH * X ^ 1 *^> o S3 be s -s 5 Q 3 | : H be o is S .2 PH * g- > :::::: H rg fr . . o ; p ; fa ^ "S .... go . . s ^ fl ^^. _ ^ w co" H 05 v. >. CO ^ s, v. ^. s oi v. fl 2 - s oo ~ a ^ O ^ CO C^l CC ^ 1C l>* Ci> O GO ^ GO OS ^ ^ 1- - - 5 5 FILTRATION EXPERIMENTS. 109 OOOOOOcDOO co co .OCDC^COOCOOJCOCO .CO .CO .COCiCOCOGCCOCOCOOOCOCOCO r> oo o o o o o o o CD ooooooo vli IT (T IG<17 IT IrHT IT IG &I) 03 o o * "S 5 (-, - S3 S-2 Ss 1 o> > ^o3 w W 41 "S o CO5OCOG<1COOCOO"CMCMI> *rHCO -H O V S" > o > - OOOO*OCMOCOOOOOOCOOO ^ HH ft H d ts ||| ll's o o o3 a ,gSSSf:SggSSggSg rH 00 t^ p 5? M 8 g>|S ^ OOOCiCMOiOOOOiOt>.Oit>.COOOirH <* GO EH fc O S i OrHOrHOOrHOOOOOOrHOrH rH rH 1 i 1 fe | 11 O O O O O 00 O CM O O O O O O CO rH T-H CM / 5 85 If o3 ^ ot>-ot>.t>.t>.ooi>.i>.oooooo !ooo rH rH rH rH rH 00 GO ?H H CJ I s o s 3 a) 1 rH . m ^ ii i -4-> s * o ^ o ^ oq w CO* o> CO Ci fl rH GO rH CMCMCMCO rHrHrHCMCMCMCM 00 02 O k o FILTRATION EXPERIMENTS. Ill co co co co .^ o o o *o so io CM* Ol C3 'M* C ^ -5 ^ > O^fuiiww4^iv^!i!wwi*s!v4v^!sSwvvv I/ ^ ^ O * Q 112 FILTRATION EXPERIMENTS. +i ll 1 CO CO GQ S3 g O of fi GO rH GO ^ II L^ O oocoocoot^t^cot^oooooooo Si "5)05 2J o o 3 S CO I O CO t^ t^ ^r^OOpOOOCOCOCO'-lOOCOOOOOO ?l o l>* t^ *O eoeoaO^HOlNOOO00000 I o o s >> 03 000 O '0 b. t- L- CO L^ CO CO O O O O O O ft f ID 1|| o o CO -* t^ GO L^ COOiO'COO-HCO- IGOCOOOOOOOOO !>.(>. L>.t>.t>.QOI>.OOt>.t>.OOQOOOOCQOOOQOOO p J 1 ^"i^ s GO O CO rHC^CO'^H'^rHCOT-HCOCOOOOOOOOO o o o ^1 03 1 -1 jjrrj C 0) [> O O O OOrHCOCOCOCOCOCOCOOOOOOOOO GO o 2tc r 8 g OOr-HCOCOCOCOCOCOCOOOOOOOOO ODOOOOOOOOGOGO-OOCOQOOOCOCOCOODCOGCOO fc ^ "S o - PI 11 O 1 r ^ g EH _,_;; O O O OOOOOOOOOOOOOOOO'OO o "o y> J s O CO *O iOiOCOCOOCOCOsOCOCOiOOiOOiOiOiOiO g o *& 1 o< O OOCOOOOOOOOOOOOOOOO "* ft 1 10 10 g CO C5 w. * oo - ~ rH JO CO L^ GOCOCO^HJOCOCT.Oi-lGOCOt-OOCr.rHCOCO-* c Q i-s FILTRATION EXPERIMENTS. 113 rH CM CM CM OJ r-i CM CM CM CO r-( . T i r-i CM r I CO . CC CO qqqqqqqcoqqq q q q 10 o q 000000000*0006^0 ! id ! o d CM' ! i>.' o OO L>- :C L>- O GO t> 1C t>- iO OO . t>. . iO !> TfH . CO ^f OlOOrHOOrHOrHCOO 'O 'OOCO qqqqqqqqqqqqoooqqqqoqq O' O' GO O -H O O to O -+ O QC L-^ L^ O d O d O* ' CC CO L^ GO L^ GO CC l>- OC L^ CXD L^ L^ t>. t^ L^ t>- l>. t^ l>. q q q q q q q q q q q q oq oq q q q q q o o o o o o o o o o o o t--' t^.' o id id id id 00 CO 00 00 CO - O5 O G J T I r-l r-H T-I r- CM CM CM CM CM (7-1 CM CM CO 15 114 FILTRATION EXPERIMENTS. s> r< g < GO 00 r i I ~ H tT cT CM GO c: GO" 'GO CM oi GO rH o GO' CM O GO' r i GO "56 ocT CM I 1 'S , ^ e & g a ~Z n3 1 CO ? CO 5. GO" CM GO" CM I ci = 1 I 5 ? ^ -o ^ ^5 & 1 CO rd g 0) -t- 1 02 a GO O Started Ap Constructec o CO 5 f^ 1 r* CO Constructei Started Ap] GO Constructec O ^ 'd 1 5 CO <| ^ ^~ ; I? o ^ 2 ^- j -sjaqumN: g^ ^^ g ^ Jl soidui'BS ^ L ^ ^^ s w K ^irea ^a a 5^ i 2; -M piO S sgj '> -p^" g ESS qj-CO S-o gg ii ^GO M irt^l S^ 1 ^ ggg c?^ 1 S o o /: IS 5 5" s p fl 2 32 ^g a 5 32 32 DO BO r-J >T r< -M -M rrt .S +3 -!-> 4^ o o O o C O & 5* o ^> cj CO yr, 3 ? l 1 | C fl g S ff c fl ~ pj o ^ ^ 05 rH rH '-S \ Jl r~o rv ^^ Qi rfi S C> s H . 1 C G ce cs GO CO nj rr C P3 c ct GO CO o s CO d b c rt "t CO CO j<3 -j ^ ~ I c CO ^ 1 1 1 i I .-: ^ oT _- -* of FILTRATION EXPERIMENTS. 115 r pnoj, jo rH r-( O t:>. CO ..?*: .2 j >, i CM* s ^U90 a9 d CO CO r-i t:^ -CO CM CM rH !>;: ! CO "o souitj, jo O O CO CM -r-i . ?* i i EH O t>- o co cr> c: ci' L^ t>- l^ L^ Ct Ci L^. ' 2 1U90U9J t>- co c^ ^ 01 o o : ; rHrH ^ rH 6 C o CO 3 o S9UIIJ, JO X O CO O CO rH rH ^1 (M -05 01 rH rH rH * V 'HH CO O -rti ^ -^ t^ ^ r-< CC CO 1 T Jj if * X ^ rH CO CO 'S91UIX JO o [..., l^ox J0 -t C: CO GO -H L- rH L ^ co CO ^ }U90 J9J ^1 t> -H ^ rH o-oi o CO 03 o rH rH rH 02 CO CO -HH t^ rf( L^ L^. L^ -HH -f CM | . 3 O ^ CM T i O ' 'OOOrH 1 r-i 01 CO "o S9UIIJ, JO c: r H ''M rH ^ . 1 ,_( ^H ^1 . "M 01 ^ H agqumsj; O CO -ti l^ ^ -f L^ HH ^ ^ ^ t - t- CO EH < 03rHOrHrHO rH IrH r-^ 6 -O -O CM EH 3 O ^ *^ . 'WOJ, JO CO -HI CO 'JO CO' CO CO CO -HH 02 < - iuao aaj t^ Ci Ql O O o oo S C5 >^ "* C C EH 'TBIOT IO CO O i i t^ L^ t^ l>. L^ L^ H L^ OJ ^ '^U90 J9J 01 b CM O -0 O -OOOr-lO CO 11 CO o S9UUJ, JO -H CO rH . .rH rH r-i rH rH Ol r- i CO rH 1C t^ ~H t>. "* t>. ^ b- C5 <5 3 'CO r^ CO O rH O rH "6 Oi 01 CO CO O3 jgqtanx CM ^ O rH CM rH . .01 ;rH . . . . . .01 -rH CO 'l B ^iL jo Cl O CM CO ^D tt CO CM . | t^ 1C CO O rH .11 -o o . CM CM 3 c EH pnoj, jo O CM CM CM i rH . CM a: - l> O Ci CMOO - O O 'i 1 rH CM 'O saratj, jo COrHrH i 1 T 1 -CM CM CO 'rH 1 $ ^ 03 CQ C0|i| 'I^IOJ, JO luao aaj OO ii t>. ^ l> t>- rH t^ L^. ^i -H^ 'S8UIIJ, JO s 's GO f- - CO 'fe 5 'P-iOJj JO ^iiao J8J 00 GO GO "* t>- ' I>- ^ L^ B8UIIJ, JO aaquinsi i i.ssjl'l l^oj, jo ^ -^ t>. T^I t^ L^- -^ t>- t>- t>- rH rH C I -O 'O rH O -OO ' saui: L L jo aaquinjsj 3 ' 4 ' lo -i o o>9 'S i ;CO v| 'I'BIOX JO t> t ^JH "-f l>- "^1 t>- ^ T^t L^ t>- OOr- l rHO' f -OrHrH O ' O S8UITJ, JO rH rH CM CM 1 CM rH CM CM rH rH /) i ^ 38 | | s 5 t CO ' r* 35 s P ? TnojL jo GO GO GO GO GO rH O' O' s8ini L L jo joquin^ 2 S^JS ^H L^ t^ C^ t^ ^ !>. -CM O O O O i i O co > 0i -g * ^j-samujo ; i i . |^ g GO 0^ ^ p 5 |g ws CM rH CM r-H rH CM sauiijj jo C 1 ' ^-4 r~ ^1 rH r- 1 C-1 O1 CO CO O t^ GO FILTRATION EXPERIMENTS. 11' 5 O O O CO O GO CO t> C: C: 'O 06 QO o 06 o r- co ; co co o o o o" co o" 06 *3 ^ -T| ^ -y the mordanting power of the alumina, the iron oxide is pre- cipitated, having nothing to keep it in solution. This is a fact which I have frequently observed in treating brown waters with alumina. The amount of sulphuric acid in the filtered water, after treat- ment with sulphate of alumina, should be the amount in the sul- phate in addition to that in the original river water. In the actual determinations made, the amount of sulphuric acid is slightly higher than the calculated amount, but not more than may be attributed to the limits of accuracy of the analytical processes. Grains per gallon. Sulphuric acid after treatment with Sulphate of Alumina. 0.5214 Ditto, in original water 0.3129 Increase due to the Sulphate of Alumina 0.2085 Amount of Sulphuric acid in one-half grain of Sulphate) of Alumina j The increase in the amount of alumina in the water after treat- ment with sulphate of alumina and filtering, is 0.0292 grain per gallon. The amount of alumina added in one-half grain of the sulphate is 0.0789 grain. This would indicate that somewhat over one-half of the sulphate was decomposed, and its alumina precipi- tated ; the remaining portion passing into solution. Thus : Grains. Amount of alumina in one-half grain of sulphate. 0.0789 Amount of alumina in one gallon of filtered river water.. . 0.0292 Total. . 0.1081 148 FILTRATION EXPERIMENTS. Amount of alumina in one gallon of water after treat- ) ment with sulphate and filtering j Amount of alumina precipitated . . 0.0407 Increase of alumina in water after treatment with sul- ") phate and filtering j" I do not attach any greater importance to these determinations of alumina than to show what took place in this single experiment. I am inclined to think from similar experiments which I have made from time to time, that the amount of alumina precipitated when a weakly-alkaline, natural surface-water is treated with a minute amount of sulphate of alumina is dependent on time, on the amount of agitation, and also on the degree of alkalinity of the water, which may vary from time to time. I think also that the precipitated alumina sometimes is redissolved in the water, in part at least, on long standing, particularly when the water has not been completely decolorized by the alumina. It is not safe to reason a priori from our knowledge of what takes place in moder- ately dilute saline solutions to what will take place in excessively dilute saline solutions in water containing considerable organic matter. Under the conditions employed in this experiment the results show that there is more alumina in the water after treatment with sulphate of alumina and filtration than there was in the natural water. This increase is 0.0292 grain per gallon, which happens to be the amount present in the original water. As to the condition in which the alumina is combined in the water, whether in its original form as sulphate, or in some other combination, it is, I think, impossible to say. The usual disposal of the acid and basic radicals among each other, as the result of an anatysis of the solid residue of evaporation of a water, is largely speculative, and does not throw much light on the condition of these substances when in solution. The increase of sulphuric acid in the water after treatment with sulphate of alumina might be a positive disadvantage when used for boilers, if the water contained sufficient lime to combine with the increased amount. In the case of the Pawtuxet River water the amount of lime is only slightly in excess of that required by the sulphuric acid naturally present in the water, so that the in- crease of sulphuric acid after treatment with sulphate of alumina can only form a very small amount of additional boiler scale. FILTRATION EXPERIMENTS. 149 From the analyses I calculate that it would require the evapora- tion of o,000 gallons of water, after treatment with sulphate of alumina, to give one ounce of additional boiler scale of sulphate of lime. A boiler evaporating 10,000 gallons in 24 hours would thus accumulate a scale of one pound of sulphate of lime in eight days, over and above the amount produced by the use of untreated Paw- tuxet River water. Finally I have determined the effect on the color of the water by treatment with sulphate of alumina. I found that the use of one-half grain of the sulphate reduced the color from 0.45 to 0.18. One grain to the gallon rendered the water practically color- less, namely, 0.02, and two grains reduced the color to 0.01. These figures refer to 'the standards of color used by the Massachusetts State Board of Health. THOMAS M. DROWN. Massachusetts Institute of Technology. Boston, July 12th, 1893. [In the above report Professor Drown uses the term " sulphuric acid" for S O 3 . He probably makes use of the term in a popular sense, as in reality S O 3 is "sulphuric anhydride" or "sulphur trioxide." The correct S} 7 mbols for sulphuric acid are H 2 SO 4 .] E. B. W. Copied Letter. HARTFORD STEAM BOILER INSPECTION AND INSURANCE Co. HARTFORD, CONN., April 15, 1893. Chemical Department. Analysis No. ... J. M. ALLEN, ESQ., President, Hartford Steam Boiler Inspection and Insurance Co., Hartford, Conn. DEAR SIR : Your note, with letter of Chas. V. Chapin of Providence, to you, making inquiry concerning the effect of alum treated waters on steam boilers, has just been received. 150 FILTRATION EXPERIMENTS. Alum, being a sulphate with an acid reaction, is much more in- jurious to a boiler than any of the salts ordinary found in waters that are inclined to cause corrosion : and the presence of a small excess of unchanged alum in a water will speedily cause quite serious corrosions, particularly if confidence in the improved quality of the water causes the boiler user to blow off and so change the water much less frequently than before, so that the alum solution becomes more and more concentrated. I have met quite a number of cases where boilers are rapidly rusted by alum treated waters, even in regions of "hard" lime bearing waters, where the alum treatment is most efficacious. In order to completely purify a water by any of the alum pro- cesses, it would appear that the alum should be very slightly in excess to insure perfect results, and it seems probable that in New England waters which often, and sometimes with quite rapid variation, contain but the slightest amount of Lime Carbonate, and of such organic matter on which an alum coagulation largely depends, the excess of alum without great care might be consider- able. However, corrosion from the use of alum is not so general as might be supposed, and I attribute this to be because either the alum is generally used in insufficient amount to entirely clear the water, or that the water either naturally contains soluble alkalies, or the rather general use at present of Soda Ash and other alka- line solvents in boilers prevents injurious action of any alum in the water. Lime Sulphate, a product of the use of the alum process, is so appreciably soluble in water as to cause trouble from formation of hard and intractable scale, second only to the alum itself. I should not consider it safe, where alum purification is employed, to run a boiler without a sufficiency of Soda Ash or similar boiler com- pound, to keep the water slightly alkaline, i to 1 Ib. per 1,000 gal- lons' would be sufficient in New England, and would also decom- pose the Lime Sulphate to the manageable Carbonate. If a red- dish powdery deposit (iron rust from alum corrosion) is noted, more Soda Ash should be used. Respectfully, GEORGE H. SEYMS, CHEMIST, (Signed) Hartford Steam Boiler Inspection and Insurance Co. FILTRATION EXPERIMENTS. 151 Copied Letter. HARTFORD STEAM BOILER INSPECTION AND INSURANCE Co. SOUTHEASTERN DEPARTMENT, B. F. JOHNSON, Chief Inspector, Atlanta, Georgia, June 27, 18U3. CHAS. V. CHAPIN, Supt. Board of Health, Providence, R. I. DEAR SIR : Your letter, of June 19th at hand, asking for information regard- ing the filtering system used by this city. I have most of the boilers, in this city, insured and under my charge. Thus far, have been unable to find any bad effect on the iron or steel, from the alum used in purifying the water. There being no corrosion or cutting, that I considered, came from the alum. I have been inspector for the Hartford company, nearly six years, and have had the boilers under my charge ever since. We have only had two batteries of boilers, in this city, that have ever given us any trouble in the way of corrosion or pitting. These batteries of boilers were located in different parts or the city and were on the end of pipe lines. Very little water was used from the street mains, except, what was used at these plants and most of the corrosion and pitting was due to rust and sediment, that settled in the mains. When valves were opened up, it was carried on, through, into the boilers. Some time ago, one of the locomotives used for shifting cars, in this city, gave way in the fire-box. There was a statement in the papers, that it was caused by the alum used for filtering the water that cut away the stay-bolts and caused the fire-box to let go. This statement was not true. The stay-bolts were broken off, by the jar and long service. Scarcely any cutting could be found on the stay-bolts. Respectfully yours, B. F. JOHNSON. 152 FILTRATION EXPERIMENTS. Copied Letter. HARTFORD STEAM BOILER INSPECTION AND INSURANCE Co. Hartford, Conn., July 17, 1803. JOHN A. GOLEM AN, ESQ., 41 Wilcox Bldg., Providence, R. 1. DEAR SIR : The question in regard to the percentage of alum in a gallon of water that would be injurious to a boiler, was referred to the undersigned by our 2d Vice President Mr. F. B. Allen. I immedi- ately called the attention of our Chemist to the subject and he replied that in his judgment one-half grain of alum in a gallon of water would not be injurious and would have no appreciable effect on the boiler. This report we supposed you had received, but it seems you had not. Large quantities of alum in water, particularly water that has lime in solution is not a good thing, as a resultant of the use of alum under such circumstances would be an increased amount of lime sulphate in the water, which produces a hard scale, so troublesome in some parts of New England ; but one-half grain, per U. S. gallon in our judgment, would do no harm. Truly yours, J. M. ALLEN, PRESIDENT. Copied Letter. HEALTH DEPARTMENT, OFFICE SUPERINTENDENT OF HEALTH, City Hall, Providence, June 11, 1894. DEAR MR. WESTON : In 1889 I visited Long Branch and examined a filter there in operation in which alum was used as a coagulent. There was no taste of alum in the water and I questioned a number of people that I met at the hotel and other places as to the presence of alum in the water and all claimed that they had never noticed it. I was referred for further information to Dr. Hunt whose statement you will find on page 43 of my report for 1889.* I at that time wrote to the health officers of places using water FILTRATION EXPERIMENTS. 153 that had been treated by alum, and received answers which you will find in the Report named. Alum has also been used for some years at Newport, though somewhat irregularly, and I have repeatedly questioned Newport physicians in regard to its effect upon the users of the water, and they all say that they have never noticed any deleterious effects. During 1893 I wrote to the health officers of some forty or fifty towns using alum-treated water, and received replies from the following places : Atlanta, Ga.; Bordentown, N. J.; Chattanooga, Term.; Elgin, 111.; Exeter, N. H.; Independence, Kan.; Lakewood, N. J.; Little Rock, Ark.; Macon, Ga.; Mt. Clemens, Mich.; Mt. Pleasant, la.; New Orleans, La.; Ottumwa, la.; Owego, N. Y.; Porterville, Cal.; Richfield Springs, N. Y.; St. Thomas, Out.; Somerville, N. J.; Sidney, O.; Trenton, Mo.; Tuckhannock, Pa.; 'Waterloo, la. In no case were any ill effects attributed to the use of water which had been treated with alum and filtered. In many instances it was stated that the effluent water had been tested by competent chemists and no alum found. In one or two instances it was stated that alum had occasionally been found in the water, but the amount was small and no bad results had been noticed. I made particular inquiries at Lakewood, N. J., through a friend who was passing the winter there. He saw the best physicians and examined into the subject quite carefully, and stated it was the unanimous opinion that the filtration of water by the Hyatt process, in which alum is used as a coagulent, resulted only in its improvement. During June of last year I visited Chattanooga and Atlanta, and had personal interviews with the health officers and other per- sons in both places, and their opinion as to the harmlessness of using the water was the same as that expressed in 1889. During the visit I paid particular attention to the effect of the filtered water upon boilers. At Chattanooga I visited a planing mill, an ice factory, two flour mills, and the power plant of the street rail- way company ; and all these users of steam were emphatic in their statements that the use of the filtered water did not produce either scale or corrosion and were all highly pleased with the process of filtering because the sediment was so much less. At Atlanta, I visited, among other places, two of the largest cotton mills, a paper mill, two ice factories, and the power plant for the street railway. All the parties visited made statements similar to those made by the users of steam at Chattanooga. I saw also the boiler-makers there who do most of the repairing and they also said that it was 20 154 FILTRATION EXPERIMENTS. their opinion that filtration improved the water and that the use of alum was never the cause of corrosion. The letter which I received from the inspector of the Hartford Steam Boiler Inspec- tion Company in Atlanta, I have already given to you. Yours truly, CHARLES V. CHAPIN. * The following letters were copied from Doctor Chapin's Report for 1889 : CHILLICOTHE, Mo., Nov. 2, 1889. DR. CHAPIN, /Sup't. Health. DEAR SIR : Yours of 29th received. In reply I will say that I have called upon all of the physicians of our city to ascertain if possible whether or no their attention had been called to the matter of alum in water, and as to whether there had been any complaint as to the purity of the water furnished our city. The prevailing opinion of our physicians and people is that the water furnished by the water works is far superior to any well water that we have in the city. As for myself and family, we use the water, and I have found no reason for complaint. We have made no analysis of the water, but as my attention has been called to the matter by your letter, I shall attend to the matter and give it a fair test. Undoubtedly, if alum is present in the water, it will be injurious to the extent of amount present. Yours truly, S. M. 13EEMAN, HEALTH OFFICER. CHATTANOOGA, TENN., Nov. 1, 1889. DR. CHARLES V. CHAPIN, City of Providence. DEAR SIR : Yours of the 29th ultimo to hand. In regard to the influence or effect of alum in our filters, I beg leave to say that they, the filters, have been in use in this city about two years. Prior to that time we took our water straight, without filtering. Since the water company have put in their filters I have noticed no increase in the amount of sickness or in death rate in our city, but, on the con- FILTRATION EXPERIMENTS. 155 trary, we are improving. Our water company are using the Na- tional filter, but I do not know to what extent they use alum. Yours respectfully, J. L. GASTON, M. D., PRESIDENT BOARD OF HEALTH. 99 E. MITCHELL STREET, ATLANTA, GA.,) Oct. 31, 1889. } CHARLES Y. CHAPIN, M. D., Superintendent of Health, Providence, H. 1. MY DEAR SIR : In answer to your inquiry of the 28th instant, I will state that the Hyatt system of filtration lias been in use in this city for about two years. A small portion of alum never exceeding one grain to the gallon is automatically injected into the water just before it enters the niters. It serves the purpose of a coagulant, and it is claimed that no part of it passes out of the niters with the clarified water. Certainly no part appreciable to the senses remains. I have used the filtered water and no other in my family constantly, and have seen no evil effects from it. In a large gen- eral practice of medicine I have never heard any complaint or ob- served any disorder that I could ascribe to it. The water is of crystal-like clearness, is sparkling and palatable to a grateful degree. Yours truly, -* JAMES B. BAIRT). LONG BRANCH, N. J., Feb. 15, 1890. DR. CHARLES Y. CHAPIN. DEAR SIR : I have not seen or heard of any deleterious or injurious effects from the use of alum in purifying city water. Respectfully, S. II. HUNT. 156 FILTRATION EXPERIMENTS. Extracts from, two papers, relative to the use of Alum in the purification of water, published in the Transactions of the Ameri- can Society of Civil Engineers. Vol. XXX., 1893. EXPERIENCES HAD DURING THE LAST TWENTY YEARS WITH WATER WORKS HAVING AN UNDERGROUND SOURCE OF SUPPLY. By B. Salbach, Baurath at Dresden, Saxony, Germany. The results found at the water works built by the author for the city of Groningen, in Holland, will be of general interest. After heavy rain storms, arid during spring freshets in the river, the water is colored brown by turf bogs situated further up stream and retains its yellowish-brownish color after filtration, although otherwise clear. To remove this color, a small quantity of alum is added to it by a small pump, while on its way to the settling basins. This addition of a saturated solution of alum amounts to about 1 to 10,000 or 1 to 20,000, of water. In the settling basins the alum is speedily distributed throughout the mass of water and greatly aids its clarification. The coloring matter contained in the water, principally iron, is precipitated, and the water, after settling from 12 to 14 hours and being filtered, becomes entirely clear and with- out color. A chemical examination of the filtered water shows that the alum disappears from the water after clarification, and that the sulphuric acid contained in the water is increased by a minute and hardly perceptible amount. A very important result was proved by the experiments of Professor Dr. von Calcar, of Groningen, viz., that during this operation, every trace of bacterial life had vanished. The system has been tried at this place for 13 years and may, in other like cases, be of great service. Vol. XXI., 1889. THE VICKSBURG SETTLING BASINS. By Clarence Delafield, M. Am. Soc. C. E. Ordinarily, the water is now found clear and admirable for use ? but at times, when the stain of the swamps is in solution, a small amount of either alum or perchloride of iron is found necessary to convert it into a form which can be removed by precipitation or nitration. A solution of alum is now used, which is introduced in absolute quantity from a tank connected by a pipe to the suc- tion main of vertical pumps, thus intimately mixing it with the FILTRATION EXPERIMENTS. 157 entire body of water, and presenting every portion to its chemical action. The result is absolutely clear water. The percentage of alum used is about one grain to the gallon, and it is entirely inert and harmless, even if not doing its proper duty. These works have now been in use several months, and the water delivered to consumers is giving perfect satisfaction. Extracts from an article published in the Chemical News of December, 1888. EXPERIMENTS UPON ALUM BAKING-POWDERS, AND THE EFFECTS UPON DIGESTION OF THE RESIDUES LEFT THEREFROM IN BREAD. By Professor J. W. Mallet, University of Virginia. Experiments upon the Influence on Digestion of Moderate Doses of Aluminum Hydroxide and Aluminum Phosphate Swallowed sJiortly before or along with Food. Having been interested by the results of a few experiments made in my own person a year or two ago on the apparent interference with digestion of these substances, I have tried a larger number of such experiments under more carefully noted conditions and with definite quantities of the materials used, in order to test directly the physiological effect of the residues from alum baking- powders, so far as this can be determined by their action in the case of a single person. The experiments were made with intervals of three or four days between them ; the food taken was of various kinds, but always simple and wholesome, and not likely of itself to produce disturb- ance of digestion ; there was no pre-existing derangement of the digestive functions when any experiment was undertaken ; as much care as possible was taken to avoid any mere fancying of expected symptoms, and to state with moderation what was actually experienced. While on two or three occasions, particularly with the smallest doses used, there was no clearly observable effect, the general tenor of the experiments seemed to establish beyond doubt on my part the fact that the ingestion of the aluminum compounds used produced an inhibitory effect on gastric digestion, while in some 158 FILTRATION EXPERIMENTS. cases, particularly with the larger doses, and on the whole rather with the hydroxide than the phosphate for equal weights of the two, the interference with the course of digestion was very notable. There was no gastric pain, nor were there any other symptoms of gastric or intestinal irritation, but simply the well-known oppres- sive sensations of indigestion properly so called, lasting for a longer or shorter time, but generally for at least two or three hours after the taking of food. The quantity of aluminum hydroxide swallowed in each experi- ment varied from 10 to 50 grains, the average for all the experi- ments being about 28 grains. The quantity of aluminum phos- phate used, ranged from 10 to 100 grains, the average being 45 grains. These doses were intentionally made larger than the quantities of the aluminum compounds in question derivable from such an amount of bread as would usually be eaten at a time if alum baking-powder in anything like usual proportion had been employed in making it. The object was to ascertain with what doses distinct effects were noticeable, arid this seemed to be gener- ally the case with any dose not less than 20 grains of the hydroxide or with not less than 30 or 40 grains of the phosphate. It may, of course, be reasonably supposed that a considerably less quantity than would be necessary to produce decided discomfort when once administered might prove objectionable and injurious if habitually taken as a part of the bread of each daily meal. With the pro- portion of alum in most of the baking-powders in use, with the allowance of two teaspoonfuls (counted as about 200 grains, though as much as 250 grains was found to be sometimes measured by a cook) of powder to a quart of flour, and assuming 35 or 40 per cent, of water in baked bread, a pound of bread would contain about 13 or 14 grains of aluminum hydroxide if alum alone were used in making the powder, or about 20 or 21 grains of aluminum phosphate if alum and calcium acid phosphate were used together, and all the aluminum were left in the bread as phosphate. As is given above, from 10 to 50 grains of Aluminum hydroxide, or hydrate, was swallowed in each experiment, and that no dis- tinct effects were noticeable with doses less than 20 grains. Also, that from 13 to 14 are generally contained in the amount of baking- powder, containing alum, used with a quart of flour. It is shown on page 43 that one-half (|) grain of Sulphate of Alumina, the average amount added per gallon to the water dur- ing the experiments with the Morison Mechanical Filter, contains FILTRATION EXPERIMENTS. 159 only about 0.08 of a grain of Alumina (Al 2 O 3 ). The result of the addition of the one-half (|) grain of Sulphate of Alumina to the water, so far as Aluminum Compounds are concerned, was the formation of about 0.12 of a grain of Aluminum Hydroxide, or Hydrate (A1 3 H G O 6 ), which was precipitated upon the filter-bed, and retained within the filter, with the exception of a minute por- tion that came through the filter-bed with the water that was being filtered, which caused the discoloration produced by the Logwood and Acetic Acid test, in the Filtered Water.] E. B..W. Copied Letter. CHEMICAL LABORATORY OF BELLEVUE HOSPITAL MEDICAL COLLEGE, EAST 2GTH STREET. NEW YORK, June 10th, 181)4. MR. E. B. WESTON. DEAR SIR : Water such as you have in Providence and we in N. Y., which holds organic matter in suspension and a small quantity of lime in solution, forms a scale at times, consisting largely of floating im- purities baked on the boiler shell and partly cemented there with the lime. When all suspended matter is removed by filtration, no new scale forms, and the old disintegrates gradually. Engineers frequently use rain water for a time in boilers to loosen scale on this principle. There is scarcely enough lime in Providence water to form scale of itself, even though calcium sulphate is practically insoluble at 3 atmospheres steam pressure. Below this what cal- cium sulphate there is in Providence water after filtration should remain dissolved, since its coefficient of solubility is such that unless the water were greatly concentrated by evaporation the saturation point would not be reached. Even under high pressures, it would require the evaporation of many thousand gallons of water for even a thin coating of calcium sulphate to appear in a boiler. Yours very truly, CHARLES A. DOREMUS. 160 FILTRATION EXPERIMENTS. Copied Letter. PROVIDENCE DYEING, BLEACHING AND CALENDERING Co. (Founded 1814.) P. O. Box, 1131. Telephone, 1708. 52 VALLEY STREET, PROVIDENCE, July 18, 1894. MR. E. B. WESTON. DEAR SIR : Our battery of six boilers was examined on Dec. 3d, 181)3, by F. D. Terry, Inspector for the Hartford Steam Boiler Insurance Co. This was six months after we commenced to feed the boilers with filtered water that had Sulphate of Alumina added to it at the average rate of -J gr. per gallon. There was nothing discovered during this examination of the boilers which indicated any in- jurious effects from the use of the filtered water. When we first began to use the filtered water, a scale or deposit which our wrought iron pipes contained was acted upon and gradually removed by the purified water flowing through them. In consequence of this the water was at times very dirty until the scale was entirely removed, which took, with our somewhat irregu- lar use of different pipes, some two weeks or more. Since then we have had no trouble with the old pipes, and we have never had any trouble with the new pipe. Yours truly, JOHN P. FABNSWORTII, TBEAS. The boilers referred to above were examined by the City In- spector on the 30th of May last, and were found in practically the same state as reported above. FILTRATION EXPERIMENTS. 101 s s "e "s 5^-2 S S ^ <^> ^> 5 s K> ^ ^ 5-s <5i ^ Ns ~i i^ (S> .* <^ ^c^ <^ CO - b ^ <* fc M3 Q ' ^ o c l ! I o o --, ^ '% W & N fl 'fH ^'&* a^-v ' ^0 ! 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O GOr- IT ICMCMrICMT 1 H^ T t O CM CO T-H r _ l oq pQ OOOO^OO 'OO pO O O >P_l?-i?-ir-iPH?-lf-l "?-l?-i^i?-if-i rH 1 +3 SSo^SS^oo ;SSooGo^ S o Q r^ Q C Q ^ ! Q ij ""^ ^ Q Q 5 H g OOOOOOOOOOOOC30QOOOOOO5O5O5ai 1 1 1 1 1 1 1 1 1 1 1 1 1 1 CiOr-ICMCOHHlOOt^QOCiO' ICM l^OOGCOOCOOOOOGOGOOOGOOiOai GOQOaOOOOOOOOOOOOOQOOOOOQOOO verages. ^ FILTRATION EXPERIMENTS. 175 COST OF FILTRATION. December 20, 1895. The following estimates have been added to the appendix at the request of the Secretary of the State Board of Health, of Rhode Island : MECHANICAL FILTRATION. ESTIMATES Nos. 1, 2, 3 AND 4. Estimates of the cost of four first-class Mechanical Filter Plants having an effective capacity each of 15,000,000 gallons per 24 hours, and the cost of operating the same when Basic Sulphate of Alumina (@ $0.02 per pound), is used, at the rate of / of a grain per gallon of water filtered. Each plant includes : A Brick building, for housing filters and auxiliaries, having an iron roof and concrete floor, including smoke stack, flues, stairs, galleries and ladders, A Wooden stor- age shed, Cast-iron pipes and connections, Gates and angle valves and wheel stands and wheels, Centrifugal pumps, in dupli- cate, Steam engines, in duplicate, Boilers, in duplicate, Boiler feed pumps and heater, Electric lighting and signalling work, Steam heating pipes, etc., Plumbing, Chemical apparatus and connections, Equipment of engine room, Application of power, Filters, etc., etc. ESTIMATE No. 1. Plant having 60 Steel Filters, and based upon an average rate of filtration, when the entire number of filters are in service, of 100,000,000 gallons per Acre per 24 hours, as recommended in the report. An actual rate of about 100,000,000 gallons would have required 58 filters, but as it was decided to arrange the filters in batteries of 3, there would have been 10 complete batteries and 1 odd filter. It was, therefore, thought best to add 2 more filters in order to have 20 complete batteries, and to be on the safe side in regard to a future increase of the consumption of water by the city. As- suming that 3 filters would be out of service the entire time on account of being washed, the remaing 57 would be obliged to filter 15,000,000 gallons per 24 hours, in addition to 735,000 gallons, the quantity required for washing the filters, and the average rate of filtration through the 57 filters while filtering 15,735,000, would be about 106,000,000 gallons per Acre per 24 hours. The reduction 176 FILTRATION EXPERIMENTS. of the rate of filtration from 128,000,000, the average rate during the experiments, to 100,000,000 was not recommended for the pur- pose of obtaining purer water than could be procured at a rate of 128,000,000 ; but in order to have a sufficient reserve for washing the filters, and to enable the filters to be run a longer time between washings than 16 h - 43 m -, the average length of time during the ex- periments (which could be brought about by reducing the rate of filtration), as it was thought that an increased length of time between washings might possibly be of advantage in the handling of a plant which would have a capacity many times larger than the experimental filter, also, to assure beyond a possible doubt, if unforeseen difficulties should be encountered in the future, of the practical working of the filter plant and a positive delivery of 15,000,000 gallons of purified water per 24 hours, in addition to the quantity required for washing the filters, at a rate of filtration not to exceed under any circumstances, 128,000,000 gallons per Acre per 24 hours. In the report I have given 15.60 as the cost per 1,000,000 gallons of operating a 15,000,000 Mechanical Filter Plant, including the cost of cleansing the filters twice a year with Caustic Soda. I have also mentioned in the report that I thought that the expense of cleansing the filters could be considerably reduced by the use of steam and other chemicals. Since 1893 I have made some care- ful investigations relative to cleansing large filters in practical operation, and I have found that the cost of cleansing can be very much reduced, from what it can be done for by using Caustic Soda, by the use of Soda Ash and Steam. In Estimates Nos. 1, 2, 3 and 4, I have, therefore, taken this reduction of cost into con- sideration, in addition to the use of unfiltered water as " rewash water " instead of filtered water, which reduces the cost of operat- ing from $5.69 to $4.52. Total Cost of filter plant $245,172, interest on total cost, per annum @ 4 per cent., $9807, annual deterioration of plant and repairs $7434, cost considering the above figures $3.15 per 1,000,000 gallons filtered, cost of operating, including cost of cleansing filters twice a year \vith "soda ash" and steam, $4.52 per 1,000,000 gallons Total cost of filtration, $7.67 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was considered, instead of " deterioration," the total cost per 1,000,000 gallons would be $7.48). FILTRATION EXPERIMENTS. 177 ESTIMATE No. 2. Plant having 60 Seasoned Cypress Wood filters. The other conditions are the same as in Estimate No. 1. Total Cost of filter plant $229,452, interest on total cost, per annum @ 4 per cent., $9178, annual deterioration of plant and .repairs, $9132, cost considering the above figures, $3.34 per 1,000,000 gallons filtered, cost of operating, including cost of cleansing filters twice a year with "soda ash" and steam, $4.52 per 1,000,000 gallons. Total cost of filtration, $7.86 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was considered, instead of "deterioration," the total cost, per 1,000,000 gallons would be $7.28). ESTIMATE No. 3. Plant having 51 Steel Filters, and based upon an average rate of filtration, through 48 of the 51 filters, of about 126,000,000 gal- lons per Acre per 24 hours (the average rate during the experi- ments being 128,000,000), while 48 of the filters are delivering an average quantity of 15,000,000 gallons per 24 hours, in addition to 735,000 gallons, the amount required for washing the filters. It is assumed that the other 3 filters will always be out of service on account of being washed, etc. The average rate of filtration through the entire number of 51 filters, if they were all in service at the same time, while delivering an average quantity of 15,735,- 000 gallons per 24 hours, would be about 119,000,000 gallons per Acre per 24 hours. Total Cost of filter plant $212,404, interest on total cost, per annum @ 4 per cent., $8496, annual deterioration of plant and repairs, $6445, cost considering the above figures, $2.73 per 1,000,- 000 gallons filtered, cost of operating, including cost of cleansing filters twice a year with "soda ash" and steam, $4.52 per 1,000,000 gallons. Total cost of filtration, $7.25 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was considered, instead of " deteri- oration," the total cost per 1,000,000 gallons would be $7.08). ESTIMATE No. 4. Plant having 51 Seasoned Cypress Wood Filters. The other conditions are the same as in Estimate No. 3. Total Cost of filter plant $198,934, interest on total cost, per 23 178 FILTRATION EXPERIMENTS. annum @ 4 per cent., $7957, annual deterioration of plant and repairs, $7888, cost considering the above figures, $2.89 per 1,000,- 000 gallons filtered, cost of operating, including cost of cleansing filters twice a year with "soda ash" and steam, $4.52 per 1,000,000 gallons. Total cost of filtration, $7.41 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was considered, instead of " deteri- oration," the total cost per 1,000,000 gallons would be $0.91). The cost of the filter plants considered in estimates Nos. 1, 2, 3 and 4, were based on actual figures given in a proposition for fur- nishing and constructing a large filter plant in 1893. NATURAL FILTRATION. ESTIMATES Nos. 5, 6, 7 AND 8. On page 055 of the Report of the State Board of Health of Massachusetts, for the year 1894, may be found the following: "More Satisfactory Results from Covered Filters, in a Climate" "as exists at Lawrence." "From experience with the out-door experimental Filters, No.'' " 3 B and 8 A, and the Lawrence city filter it appears that the " "difficulty in scraping the surface during the winter months is" "so great that it is advisable to provide water filters with covers" "in this climate." On April 18, 1895, the Water Board of Lawrence, Massachusetts, received a communication from the designer of the Two and One- half (2^) Acre Natural Filter-bed at Lawrence which first went into operation in September, 1893, recommending the covering of the filter-bed. Soon after, the Water Board requested the City Engineer of Lawrence to make plans to cover the bed. On June 28, plans were submitted to the Board, the estimated cost of which was $40,000. The covering which was designed for the filter-bed was to be of wood, with a roof to be covered with two-inch plank, with skylights, and sheathing inside, to make an air space to assist in preventing freezing. The Total Cost charged to the construction of the Lawrence Filter, to January 1, 1894, was $09,531.74. The Cost for Mainten- ance, labor and care of the Filter, during the year 1894, was $4014.50, and the Total Quantity pumped from the Filter during the year was 1,049,938,320 gallons. The Cost of Filtration, etc., per 1,000,000 gallons, during the year 1894, therefore, was $4.39. FILTRATION EXPERIMENTS. 179 From "The Filtration of Public Water-supplies, by Allen" "Hazen, Late Chemist in charge of the Lawrence Experiment" "Station of the Massachusetts State Board of Health," published in 1894, the following extracts relative to "Covers for Filters," have been taken : "An addition to the Berlin niters, built in 1874, was covered" " with masonry vaulting, over which several feet of earth were " " placed, affording a complete protection against frost. The niters " " at Magdeburg built two years later were covered in the same way," "and since that time covered niters have been built at perhaps a" " dozen different places." "Roofs have been used in Konigsberg, Posen, and Budapest" " instead of the masonry vaulting. They are cheaper, but do not" " afford as good protection against frost, and even with great care " " some ice will form under them." " To supply a maximum of 10,000,000 gallons daily, five niters " " each with an area of one acre will be ample. Any four of them " " can easily furnish this quantity while the fifth is out of use for " "cleaning or other cause. If the city is north of the line of nor-" " mal January temperature of 32, vaulted niters will be required." " Some estimates recently made by the author in connection " "with engineers examining the Boston Metropolitan Water-sup-" "ply indicate that filters fully up to the German standards, but" "with beds of a full acre each, and with vaulting substantially" "like that successfully used on the Newton covered reservoir," " can be built at present American prices for somewhat less than " " the cost given above, notwithstanding the higher price paid for " " American labor." " Including the connection with the (existing) pumping-station " " we may estimate the cost of our five acres at $350,000, with a " " probability that with favorable local conditions the expenditure " "would be still less." ESTIMATE No. 5. Filter-beds Covered with Masonry Vaulting, based upon Mr. Hazen's figures given above. 15,000,000-^ 10,000,000 = 1.5,- 1.5x $350,000=4525,000 as the Total Cost of the Filter-beds, interest 1BO FILTRATION EXPERIMENTS. on total cost, per annum @ 4 per cent., $21,000, deterioration and repairs, per annum, $3,500, cost considering these figures, $4.47 per 1,000,000 gallons, assumed cost of operating the filters, $4.30 per 1,000,000 gallons (the same as the cost at Lawrence for the year 1894). Total cost of filtration, $8.86 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was considered, instead of "deteriora- tion," the total cost per 1,000,000 gallons would be $10.30). ESTIMATE No. 0. Filter-beds Covered with Wood, based upon the figures given above relating to the two and one-half (2.5) acre filter-bed at Law- rence, Mass., and assuming the rate of filtration 2,000,000 gallons per Acre per 24 hours, should all of the beds be in service at the same time, and 2,500,000 when four-fifths (|) of the beds are in service, and one-fifth (-J-) out of use for cleaning or other cause. $69,5324-2.5=427,813, cost of beds per acre, $40,000-3-2.5 = $16,- 000, cost of covering with wood per acre, 15,000,000 -=-2,000,000 = 7.5, cost of beds $27,813 x 7.5=8208,598, cost of covering with wood, $16,000 ><7.5 = $120,000, Total Cost of filter-beds $208,598+$120,000=$328,598, interest on total cost, per annum @ 4 per cent., $13,144, deterioration and repairs per annum, $7391, cost considering these figures, $3.75 per 1,000,000 gallons, assumed cost of operating the filters, $4.39 per 1,000,000 gallons (the same as the cost at Lawrence for the year 1894). Total cost of filtration, $8 J 4 per 1,000,000 gallons. (If 2 per cent, for a sink- ing fund was considered, instead of "deterioration," the total cost per 1,000,000 gallons would be $8.05). ESTIMATE No. 7. Conditions the same as in Estimate No. 6, with the exception that the rate of filtration is assumed to be 2,500,000 gallons per Acre per 24 hours, should all of the beds be in service at the same time, and 3,125,000 when four-fifths (-f) of the beds are in service, and one-fifth (^) out of service for cleaning or other cause. 15,- 000,000-5-2,500,000 = 6, cost of beds $27,813 X 6=$166,87S, cost of covering with wood, $96,000, Total Cost of filter-beds $166,878+ $96,000=$262,878, interest on total cost, per annum @ 4 per cent., $10,515, deterioration and repairs per annum, $5913, cost con- sidering these figures, $3.00 per 1,000,000 gallons, assumed cost of FILTRATION EXPERIMENTS. 181 operating the filters, $4.39 per 1,000,000 gallons (the same as the cost at Lawrence for the year 189-4). Total cost of filtration, $7.39 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was con- sidered, instead of "deterioration,", the total cost per 1,000,000 gallons would be $7.32). ESTIMATE No. 8. The following estimate is based upon my own figures : Ten (10) filter-beds, not covered, having an area of 0.94 of an Acre each, to filter at a rate not to exceed 2,000,000 gallons per Acre per 24 hours, and to have a depth of water over the top of the beds of about 4 feet. Eight (8) of these beds to filter at the rate of 2,000,- 000, and to have a capacity of 15,000,000 gallons per 24 hours. The other two (2) filter-beds are to be held in reserve for cleaning or other cause. Total Cost of the filter-beds $291,220, assuming that a suitable quality of sand, which would not need to be washed nor require much screening, could be obtained for the filtering medium in the immediate vicinity of the location of the filter-beds, interest on total cost, per annum @4 per cent, $11,649, deterioration and re- pairs per annum, $1,941, cost considering these figures, $2.48 per 1,000,000 gallons, assumed cost of operating the plant, $4.39 per 1,000,000 gallons (the same as the cost at Lawrence for the year 1894). Total cost, of filtration, $6.87 per 1,000,000 gallons. (If 2 per cent, for a sinking fund was considered, instead of "deteriora- tion," the total cost per 1,000,000 gallons would be $7.07). ( SUMMARY OF THE ABOVE ESTIMATES. The figures in parentheses include 2 per cent, for a sinking fund instead of " deterioration." MFPI T FriT Total Cost Cost per 1,000,000 of Plant. Gallons Filtered. Estimate No. 1. Including 60 "Steel" Filters $245,172 $7.67 ($7.48) No. 2. Including 60 "Cypress" Filters - $229,452 $7.86 ($7.28) No. 3. Including 51 "Steel" Filters $212,404 $7.25 ($7.08) No. 4. Including 51 "Cypress" Filters $198,934 $7.41 ($6.91) 182 FILTRATION EXPERIMENTS. NO,UL Fn,ON. Total Cost oo* per Estimate No. 5. Filter-beds covered with Masonry Vault- ing, Rate of Filtra- tion 2,000,000 and 2,500,000 ........... $25,000 $8.86 ($10.30) " No. 6. Filter-beds covered with Wood, Rate of Filtration 2,000,000 and 2,500,000 ....... ' $328,598 $8.14 ($8.05) No. 7. Filter-beds covered with Wood, Rate of Filtration 2,500,000 and 3,125,000 ....... $262,878 $7.39 ($7.32) " No. 8. Filter-beds Not Cov- ered, Rate of Filtra- tion 2,000,000 ....... $291,220 $6.87 ($7.67) In the estimates of each of the Mechanical Filter Plants, I have assumed that the ground upon which they would be erected was graded, and of a character suitable for the foundation of the build- ing, etc., to rest upon, and in the estimates of the Natural Filter- beds I have assumed that the excavation would be suitable for the construction of the embankments and that not any more than the ordinary difficulties of construction would be encountered. In any of the estimates I have not considered the cost of settling basins, if such should be needed, nor pipes nor conduits leading to and from the niters, etc., etc. Also, I have not considered the cost of land in any of the estimates, which would be of considerable importance in some localities and probably exert more or less influence in the selection of a filter-plant, as, for instance, the Mechanical Filter Plant considered in Estimate No. 1 could be enclosed within an area of less than 1 Acre, while the Natural Filter-beds considered in Estimate No. 8, would require in all probability at least an area of 16 Acres for their site. E. B. W. 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