摘要:

ON THE VALUATION OF THE BELATIVE IMPUhITILS IN POTABLE WATERS. BY c f . W. WIGNEB, F.C.S., F.I.C. Read before the Society of Public Analysts, on 1st June, 1880. ABOUT three years ago I submitted to the Society a scheme for the systematic valuation of the impurities found in potable waters, based upon the plan of giving a value to every constituent found in a water. This scheme was discussed at the time, and some suggestions then made were adopted and have rendered it more generally applicable. During three years the scheme has been tried by many analyets, and it is in consequence possible to discuss it with greater advantage. Some six months ago the Water Committee of the Society very carefully considered the scale, and after a slight alteration of two or three items, it was decided to give it a temporary trial on the analyses of public water supplies made by the members of the Society for publication in THE ANALYST, and to bring the subject forward for discussion at this meeting.In considering the details, one result of the alterations from the original scale must be borne in mind. Certain values have been altered, Rnd consequently the value of 85 which 1 proposocl as tho limit of a Iirst-claw water iuay bo no luagcr tenablc, m d I ~ l l ~ l lPI2 THE ANALYST. therefore submit another proposal for that limit. It appears probable that we may find some further alterations are necessary in order to make it universslly applicable to the various classes of waters from which public supplies are drawn. I will at once assume that all analysts are agreed on the desirability of greater uniformity in the expression of opinion on the results of water analyses, as well as in the mode in which the analyses should be carried out.In almost every case the purpose for which a water analysis is made is to obtain an opinion as to purity and suitabilityfor domestic me, but at present it is a not uncommon occurrence that two analysts obtain results which are almost identical, and yet they differ considerably in the opinion they give on those results. It is with a view to obviate this undesirable state of things that we are to discuss the matter to-liight. There are certain points which will be very generally assented to, and may be used ac, starting points for the purpose of testing the proposed scale.First. Every constituent faund in the course of an ordinary water analysis must have E certain value or importance corresponding to the propGrtion in which it is found, no matte: how small that proportion may be. I t is quite true that when certain constituents, say, fol instance, chlorine in chlorides or nitrogen in nitrates are present in very small proportions only, their importance may be so slight that they are ordinarily ignored in forming a1 opinion, but it is a more sound and logical course to consider their importance or value small as it mag be, as forming part of a total rather than to consider the determinations a valueless. If any constituent of a water, no matter what, is found in undue or excessiv proportion, it ought to be suflicient to condemn that water for domestic use.There must be a certain minimum valuation approximating to that of th purest public supplies which should be passed as representing the constituents natural1 occurring in the best waters. At first sight, it might appear wiser to allow a certai proportion of each constituent individually, say for instance 1 grain of chlorine or *1 grai of nitrogen in nitrates, before the valuation; but in practice it is more convenient, and o the wholo more satisfactory, to assume that if the valuation of all the constitueni is less than say 15, the water is classed as of exceptional purity; and, similarly, may be desirable to make a deduction corresponding to this figure in fixing the arbitrai limits between waters of different classes. Having deducted or allowed for the amount of mineral and organ constituents found in the best waters, we shall get a residual figure which will raprese what may be called extraneous impurity, and this will really be the measure of the exce value of all the constituents determined, over what is present in the purest water supplic I t is practically certain that this difference, which is in fact the valuation of the extraneo impurities, will show clearly and reliably the variations which take place from week to we and month to month in the character of any one supply.But it is only by looking carefu at the details of the valuation scale that it is possible to see whether it will act with eqr efficiency and certainty on supplies drawn from different sources, and on water stored filtered in different ways.It has been suggested that it will be necessary in some cases to m a b a lot allomnee or deduction, because of tho difficulty of procuring a satiefactory water supply Second. Third. Fourth.THE ANAIJYST. 118 c e r t h parts of the country. The suggestion is unquestionably an important one; but it appears to me that it is preferable to report that the water of a certain diatrict is less pure or more pure; leaving the fact of this difference of purity to be studied in a way which has not hitherto been practicable, because direct comparison of the characters of the waters has been extremely di5cult. The scale, as provisionally adopted by the Water Committee, had distinct reference to the scheme of water analysis formulated by them, and omits all reference to values to be given to organic carbon and nitrogen, and to the detailed mineral analysis,.nor is any reference made to any value for the presence of heavy metals. It is obvious that some such allowance as the last is necessary, and when organic carbon and nitrogen are determined, definite values should be given to them in substitution for the values belonging to the albuminoid ammonia. The scale, as far as the purely chemical results are concerned, is as follows :- ... ... Chlorine--.50 grn. per gallon ... ... ... ... equal 1 Phorrphoric Acid-Traces ... ... ... ... ... ... ,, 2 9 , Heavy Traces ... ... ... ... ... ) ) 4 $ 9 Very heavy Traces ... ... ... ... ... ,, 8 Nitrogen in Nitrates -010 grn, per gallon , , . ... ... . . . . . 1 ...... ... ... . . . . . 1 Ammonia, free -405 9 , , , Albuminoid--.001 9 7 ... ... ... . . . . . I Oxygen absorbed in 2 minutes-0002 . , . ... ... ... . . . . . I 9 ) P 9 4 hours --.010 ... ... ... ... . . . . . I Hardness before and after boiling (added together)-sU 3 , 1 Total solid matter-5 grs. per gallon ... ... ... .I. ... 9 , 1 ... ... If my single value exceeds 10 the excess over ten is to be doubled and included in the addition. The values for the physical determinations will be found at the end of this paper. Thus far the scale is convenient and of such a character that no analyst can have any difficulty in applying it to the results of any analysis, but as regards its application to the physical tests, viz., appearance, smell, and microscopical examination, its application is attended with more difficulty, and, as a natural consequence, more uncertainty.While, therefore, I will consider the scalc! to-night in the first instance as published by the Water Committee, I shall suggest some alterations as regards these physical characters in order to render it feasible for different analysts working on their own results to obtaill the game figures of valuation. I wish to put the scale itself to a crucial test by applying it to three or four series of water analyses, and for this purpose I have had a sheet of tabulated analyses printed, the results of the physical tests being applied as accurately as is practicable. The first series of waters to which I propose to caIl attention are 21 taken on the course of the Surrey Bourne, which is generally an underground river, but which has been flowing above ground during the last few months.The samples are arranged in coneecutive order according to the flow of the river, commencing at the top of the watershed and following the course of the river through the whole of the valley, either on the surface or below ground, as the cage may be; by taking samples from every well which is in trhe clirect line of the114 THE ANALYST. flow, and by sampling the flowing river itself at several intermediate points. All the samples were drawn on the same day, commencing at the top or source of the river and following the flow of the water downwards--(Table I.) It is obvious on the first glance at the analyses that the water is fairly pure chalk water, and applying the valuation scale to it we find that out of the 21 samples, 7 show a valuation of 27, 3 of 28, and 2 of 29, or 12 samples agree within reasonable limits, and so give what we may consider as a standard of purity for judging of the bulk of the water, and enable local or accidental contamination to be more readily discovered and valued.We have now to deal with 9 samples which show a greater valuation than 29, and we can consider these more contaminated samples with a special advantage which does not apply to the other analyses I shall submit to you, because I have been over the whole of the course with Mr. Baldwin Latham, who has for many years studied this remarkable subterranean waterflow, and we have visited each place from which samples have been obtained, and traced out as far as practicable any possible pollution which may have occurred.No, 1, At the commencement of the Bourne the water might be expected to be of a high standard of purity, but it is not so, and on examination we find that at the place where the sample was taken, a large number of men and animals were at work, and that the excreta and dirt to some extent were passing into the outflow and contaminating the water, Four columns of this analysis show increased values, and the differences, although small in each constituent, so small in fact as to pas8 almost unnoticed, pet give a valuation of 8 more than the next sample. At No. 6 there is again an increased value, and here it is found that drainage water from cultivated and presumably manured ground is contributing to the flow.On looking at the figures of the analysis, the dnly changes which attract attention are the increases in the chlorine which has nearly doubled, and in the nitrogen in nitrates; the results of the microscopical examination are somewhat less satisfactory, but yet taking all the figures and giving each the increased weight which it claims, seven columns give higher figures and the valuation increases to 42. As the Bourne flows down the valley purification to some extent takes place, but at Yo, 8 we come to a sudden and remarkable increase in the valuation, which rises to 47. The cause is easy to find. The well from which the sample was drawn is in close proximity to a cesspool, and consequently, although no one figure of the analysis is altered very greatly except the chlorine, seven of the constituents slhow an increased valuation.No single figure shows increase enough to condemn the water, but the collective figures show that the value rises from 27 to 47, and if the water is not a second class one it is so near the margin as tc be viewed with suspicion. The flowing Bourne soon seems to get rid of this contamination, and I need not refei to one slight change at No. 12, further than to say that the proximity of a farm tells on the valuation, but pass on to No. 14, where the valuation suddenly rises from 27 to 46 Chlorine is lower than in the case of the last sample we considered; the nitrates havt increased very greatly ; ammonia and albuminoid ammonia show very little change ; bu there is an increase in oxygen absorbed, and perhaps a slightly worse result from thu microscopical examination.Taking all the figures, however, eight different columns of thaTHE ANALYST. 115 valuation rise to tell the tale of another adjacent cesspool, and the water is at once marked as relatively polluted, although the analysis does not show any single excessively high figure. Now these results, all obtained on the aame general water flow, and for all practical purpoaes on the same water, with tho sources of contamination thus accurately sought out, show that the broad principle of the valuation is correct, and even the figures of the scale itself are not likely to be far wrong when a cesspocl or some manured fields in the neighbourhood of a flow averaging some six million gallons a day is thus distinctly indicated.In 13 of them, Nos. 2, 3, 6, 9, 10, 11, 13, 16, 17, 18, 19, 20, 21, we have values ranging between 27 and 30, one only reaching the latter figure. These samplenr being all approximately of the same quality and the same class of water, may be fairly averaged so as to arrive at the measure of condemnation afforded to each constituent. The average value tattsohed to the microscopioal examination is 7.1 or one-fourth of the total. The microscope showed vegetable debris, animaloulae, mycelium and spores, with in one cam fragments of straw and hair. These microscopical results of course are not satisfactory, and on the whole, the relative condemnation afforded by a valuation of 7.1 for them seems just.The hardnese and total solids together give:an average valuation of 7*5 or rather more than one-fourth of the total. Considering that this water is on the whole a pure one, but very hard, it does not appear that this valuation of solid matters and hardness is too high. The nitrogen in nitrates gives an average valuation of 3-7 corresponding to 037 grains pregent. This proportion is of course considerably above the average of that found in public supplies ; in fact, taking the March waters as reported in THE ANALYST, we only find four cases out of those 40 or 50 publio supplies where such a large proportion was found. Therefore, although nitric acid is of less importance in a chalk water than in a shallow well water, it does not seem that the valuation assumed gives any undue relative importance to it.The valuation for ammonia, free and saline, has been greatly increased since I originally laid the scale before the Society, but, judging from this series of analyses, it does not seem to be too high. Thus we find that the valuation of the ammonia in the whole of these 13 waters averages only '5, and taking our May table of analyses there are only two waters which give a value exceeding 1, viz., King's Lynn 1-1, and Oldham 3.0. Oxygen absorbed in two minutes and in four hours added together, shows an average valuation of only 1-0 on these waters; but from some other analyses, which I shall refer to later on, it will be seen that in the case of some peaty waters the condemnation value of oxygen absorbed becomes rather high, and I shall proponre ft modification which I think will be necessary.We next have (Table 11.) a series of hard chalk waters, two of which, viz., the supply of Canterbury in two different months, have been softened by the Clark process. In these analyses the microscopical results are almost uniformly satisfactory, and the table may be taken as very fairly representing the character of deep chalk wells through the greater part of the country. A comparison of the analyaes of the samples from Cambridge and from Canterbury will give a fair estimate of the improvement which, according to thig valuation, is obtained We can, with advantage, make another study from these analyses.116 THE ANALSST. by the treatment of a water by the Clark process. The two watem before treatment are very similar in character, whereas after treatment the valuation is lowered from 23 to 14 or 15, this result being effected by decrease in the nitrogen in nitrates, ammonia, albuminoid ammonia, oxygen absorbed, hardness, and total solids.The first eleven waters of this series are all samples supplied by the Kent Company, or drawn from their different wells. Only two of these call for special attention, one because the valuation is low and one because it is high. The sample from the Shortlands wells gives a valuation of only 19, and on comparing this with the next sample it will be seen that the difference of 4 in the value is accounted for by decreases in the figures in seven different columns, The sample of Kent water supplied for February shows a higher valuation, viz., 37, and this appears to be due to increases in nine different columns of the analysis, as com- pared with the January analysis of the same supply, the most important change, however, being produced by large increases in the proportions of nitrogen in nitrates and albuminoid ammonia.I now propose to make some comparisons in a different way, by considering the supplies of the companies drawing their water partly or entirely from the river Thames, illustrated by the analyses made by our members in January, March and May of this year. I include the New River in this series, because part of that water is taken from the Thames . It appears to me, that with the generally satisfactory character of the London tables of mortality, the general state of health of the population, and last, but by no means least, the great neglect of proper sanitary precautions in the house cisterns of the metropolis, we are bound to say that London water as supplied by these different companies, must, under ordinary circumstances, be considered of first-class quality.These waters (Table 111) should give us an idea of a definite limit or standard by which to define a first clam water, They would give us a valuation of about 40 as that at which the limit between first and second class water should probablj be drawn, and allowing for the alterations in the scale this would correspond closely with the original limit of 35 which I suggested. Two samples only out of the 18 contained in the table, show a valuation exceeding 40; while 9, or 50 per cent.show valuations between 20 and 30. In February four of the London waters exoeeded this limit and in April every sample was below it. This table may be considered in a different way from the Surrey Bourne series. All these waters have received certain and tolerably accurately known amounts of pollution, and have afterwards been subjected to oxidation, which is probably as complete as that rweiveci by most river waters. Unless, therefore, an exception is made for the Lambeth Compaiiy, whioh is pumping a considerable portion of its supply from the gravel, and this portion is probably different in character to the river water, these analyes must be considered and explained without the addition of any extraneous information. The average valuation of these six companies’ water during the last five mcnths have been, Southmark and Vauxhall, 35 ; West Middlesex, 29 ; Grand .Junction, 31 ; Lambeth, 39 ; Chelsea, 31 ; New River, 28 ; or taking those only included in Table III,, Southwark and Vauxhall, 31 ; West Middlesex, 80 ; Grand Junction, 32; Lambeth, 41 ; Chelsea, 30 ; and New River, 29.On the average results, therefore, me have no exceptional figures except possibly in the caw of the Lambeth water.IIaR1,sb: ss, Clnrh'ti Scale, u degrees. c? a Phosphoric '$ Acid in -0: Phosphates. .; 2 2 'k 3licrowopical Examinntion of Doposit. 2 ruins. 3 hours nt 800 at 80' Pahr. Fnlir. I 1.2:: 1.2q 1.42 1-42 2.63 1.42 1.13 3.00 1-13 1.28 1.10 1.22 1-31 2.06 l-;iO 1-25 1.42 1-42 1.28 1-12 1-53 I inid. mttr. liair veg. deb.veg. deb. animnl. mycelium diatoms. xcg. clcb. veg. deb. fib. spores vort. hair f anml. alp,{ . wfi. (ltib. cv fib. 1 reg. dell. spores ,miin. Peg. deb. mj ccliuin anirri. h i 1 veg. deb. fibs. dnis. algam. hair veg. deb. mycelium ;iuiiii. veg. deb. fibiw m i i i r . veg. deb. fibres anim. v o ~ ticP11:i veg. deb. fibres anim. veg. deb. ~ I ~ C S auini. veg. deb. fibres anim. veg. deb. fibres anim. veg. deb. fibres anim. veg. deb. auim. spores veg. deb. fib. spoies snim. veg. deb. fibies anim. hair veg. deb. fib. anini. sprs. strav reg. deb. fibres auini. ( 1.01~. 1 ~ ~ L t d i L i l ~ j 35 29 25 35 42 30 33 47 27 a7 27 32 27 46 31 27 as 29 28 27 27 30.40 18.00 24.60 30.00 30.80 19.00 26-10 31.40 23.80 24.60 '31.16 21.00 24.20 :Ei.oo 24.40 23.00 26.00 22.00 22.00 22.40 20.80 TABLX I.- Burrey Bourne WaterB- 1 ,.........................traces traces triXcCS trace., tmces traces traces h. traces t mces traces traces traces traces h. traces t8ract.s traces traces t rac (8s tr'icees traces tiaces yxle. yelw. white cltlliy. slight c. yellow blue \ eg.&eartj-. c. yellow blue none c . greenish v. slight 4 . . . . . . . . . . . . . . .. . . . . . . * . . . .j . . . . . . . . . . . . . . . . . . . . . . . . . .Ic. p. blue, ycllow tinge) slight none nolie none none none none s. veget. none none none none none none v. slight none slight G . . . . . . . . . . . . . . . . . . . . . . . . . . s. opaque yellow green 7 . . . . . . . . . . . . . . . . . . . . . . . . . . 8 . . . . . . . . . . . . . . . , . . . . . . .. . . s. opqe. blueyelw. tinge 9 . . . . . . . . . . , . . . . . . . . . . . . . . . 10 . . . , . . . . . . . . . . . . . . . . . . . . . . 11 ..............I........... c. greenish 12 . . . . . . . . . , . . . . . . . . . . . . . . . , s. opqe. yelw. tinge brn 13 . . . . . . . . . . . . . . . . . . . . . . . . . . c. greenish tinge brow 14 .. . . .. . . . . . . . . . , . . . . . . . . . . 15 . . . . . . . . . . . . . . . . . . . . . . . , . . s. opqe. greenish yelw 26 . . . . . . . . . . . . . . . . . . . , . . . . . . 17 . . . . . . . . . . . . . . . . . . . . . . . . . . 18 . . . . . . . . . . . . . . , . . . . . . . . . . . s. opaque yellow green 19 . , . . . . . . . . . . . . . . . . . . . . . . . . 20 . . . . . . . . . . . . . . . . . . . . . . . . . . 21 .. . . . . . . . . . . . . . . . . . . . . . . ~, c. greenish tinge bromii c. yellow brown c. yellow blue c. yellow brown c . greenish c. blue green c . greenish yellow 0. yellow green c. greenish blue 1.77 l.(i3 1-77 1-20 %.S4 1.20 1-77 1.35 1.84 1 *!r 1 2.15 1-37 1.47 1.22 1.31 1.47 1.47 c. pale blue e. pale blue c. pale blue c. pale blue c. pale blue c. pale bliie c. pale blue p. blue greeiiish c. pale blue c. blne green f. hlne c . p. blne colol?l lcss c. colourless c. 1,111e p ldne TABLE 11.- Deep Challi Well Waterw- none none none none none none none sliglit v. sliglit none none nolie now none none 11one l l 0 l l C traces h. trnces traces traces iioiie none none nonc none trncts trims 11. traces tl-aces traccs tr<ices nolie llolle 23 25 21 21 26 19 23 23 37 23 27 31 23 14 15 20 80 Kent Bath Well .. . . . . . . . . . . . . ,, Crayforcl Well . . . . . . . . . . ,, Garden Engine Well.. . . . . , , Orpington Well . . . . . . . . . . ,, P1uniste;td ,, .. .. .. .. .., ,, Shortlands ,, . . . . . . . . . ,, Twinswell ,, . . . . . . . . . . ' ,Jan. Kent . . . . . . . . . . . . . . . .' Feb. Kent . . . . . . . . . . . , . . . . March Kent ...... .. .. .. .. .. April Kent ...... .. .. .. .. .. Jan. Cambridge ............ April Cambridge . . . . . . . . . . . . Jan. Sevenoaks ............ Narch Sevenoaks . . . . . . . . . . . . Jan. Canterbury.. . . . . . . . . . . April Canterbury. . . . . . . . . . . . TABLE 111.- Thames and other London River Supplies Jail. March Jan. Narch Jan. JIarch Nay Jan. 7 March May Jan. March 3f ay Jan.Mnrch 31 ay M,zy May S out li\varB an il Vauxh all Southwark and Vauxhall Sonthmark and Vauxhall Wcst Middlesex. . . . . . . . West Middlesex.. . . . . . . TI7 e st IIid dles ex . . . . . . . . Grand Junction. . . . . . . . Gr:~nd Junction. . . . . . . . Grand Junction. . . . . . . . Lambeih . . . . . . . . . . . . Lainbeth . . . . . . . . . . . . , . Lambeth . . . . . . . . . . . . . . Chelsea . . . . . . . . . . . . . . Chelsea . . . . . . . . . . . . . . Chelsea . . . . . . . . . . . . . . New Lliver . . . . . . . . . . . . New River . . . . . . , . . . . . Kew River . . . . . . . . . . . . p. yellow s. yellow T. p. greenish yelhw c. yellon f . yelloJy 3 eilowish f. yellow p. yellow p. j-ellow mkd. yellow yellow v. p. green yellom greenish yellow greenish ~ ~ l l o m p.greenish bron-n c. f. tint c. f. yellow c. f. yrllom 111 ill(' l l 0 l l C n0nc none iinlte none none none slight none none iioiie none none none none none 11011<> traces t ?' ac: 1'5 h i ccs traces tritces tr:1ccs tlxces tritccs tr:icc's traces t 1': 1 c C' s tracts , h. traces ' traces traces traces traces traces satisfactory v. s. mineral mineral cliams. &L infusorin amorph. organic matter sntisfnctory disfactory none satisfnutory none veg. deb. mvg. organisms miid. mttr. nivg. organisms s. mineral & diiitoins iioiie sntisfactory good none sntisfactory satisfactory 28 39 36 39 29 21 28 39 28 52 46 28 35 33 22 23 31 24 .011 *013 *22 1 -074 none none none none nolie none none *093 .077 llolle llolte -xAr$.-w Waters from Millstone Grits, Peaty Ground, &c.- &$nrcli May March May Jan.March Jan. hf arch May Jan. Ilarch Nay Mar ch Nay MIay p"' 'teliat-cn . . . . . . . . . . M. tehtiven . . . . . . . . . . Derby . . . . . . . . . . . . . . . . Derby , . . . . . . . . . . . . . . . Manchester . . . . . . . . . . llnncliester . . . . . . . . . . Rlanchester . . . . . . . . . . Leeds . . . . . . . . . . . . . . . . Leeds ................ Leeds . . . . . . . . . . . . . . . . Bradford. . . . . . . . . . . . . . Bradford. . . . . . . . . . . . . . Bradford.. . . . . . . . . . . . . Liverpool . . . . . . . . . . . . Liverpool . . . . . . . , . , . . f . 61 "('n c . f . ereen 1. gond \ . g"0d s. tnrlnid s. turbid. f. ycllow yello\y green light brown light brown jcllo\\- bron n f. tlirty j-ellow peaty yellow opaque s.yellow opaque yellowish brown greenish yellow none nonc none none peaty none none peaty none iione none nolie iioiie peaty peaty veg. deb. diatoms \ (1:;. 17eh. tiiatomr h:it i sf ac tory none anti sf actory 5. mineral sand pegty matter peaty imtter peaty matter boric none none wntisfacto1.y 8 \tihfrwtor,v ?-at: .f < I ctory 9 9 12 12 21 23 21 40 36 4 0 40 65 57 41 31 110110 none none s. trace traces n01;c iioiie t ra ce s traces traces none none none traccs traces -1 ' L 13.2' ,;*!I 11.1' k.4 1.0' 1 - y r 1.;y 1.7' 1.6' 3.2c 2.9 4.0L 2.9' 3.6' 3.0' 4.2" 3.7" 4.2" 4 9' 4.P 3.T 5.2" 5.0' 4.6" .$*Ac 15-60 12.2" 13.4" 12,s' 4.0' 3.0' 11.0' 5.2' 22.0" 12.0° 28.6' 26.8" 14.2" 12.00 29.0" l 4 . O C 7 - 7 O 7.7" 1G.U" 6.7" 1 8 9 O 1.5' 16-0' 5.2" 17.6" 10.4" 14.4" 8.9" 9.-10 1.86 1.60 2.40 4.47 (1.23 6.78 6-74 I 6-63 4.50 1.47 35.10 42.12 10.23 ~ 40-18 -0045 .0113 -0086 *0075 4104 m 1 9 .0079 -0118 -0101 a0113 *0134 .0090 a0763 TARLE V.- Sundry Waters not previously pnblished- 18.00 32.00 S.I,0 20.40 50.70 43-40 44-80 67.30 42-10 57.90 28.60 66.20 78.00 52-60 33 56 38 41 63 73 H a 89 89 133 166 198 '2 18 500 A.Deep well . . . . . . . . . . . , . . . . B. Shdlow well . . . . . . . . . . . . . . I). Well.. .. . . . . .. .. .. . . .. .... E. Well.. . . . . ~. . . . . . . . . . . . . . . F. Shitllo~v well . . . . . . . . . . , . . . G. Well.. . . . . . . . . . . . . . . . . . . . . H. Well.. .. .. .. .. .. .. ...... .. J. Shallow well . . . . . . . . . . . . . . K. Deep .. . . .. .. .. . . .. .. .... L.River . . . . . . . . . . . , . . . . . . . . M. Deep wcll . . . . . . . . . , . . . . . . N. Deep well . . . . . . , . . . . . . , . . 0. Public Supply from Brook . . c. 1~7~11. . . . . . . . . . . . . . . . . . . . . . mtisfnctoi y sntisfac tor>- veg. deb. mycelium fibres sand satisfactorj ~a ti sf tict ory veg. and other de\)l-i+ vcg. deb. spores veg. deb. mycelium veg. fibres & leaves fib. anl. hair qtz. mncl veg. deb. auim. cott. fib. mj-cclimn hair veg. deb. fib. spozcs rtuim. CQC. veg. deb. spores fibres aiiini. veg. deb. much clecomp. anim. -0027 -0043 -00% a0015 a 0 2 1 -0010 -0so1 -0078 -0009 .ill95 -0013 -0130 -0011 -0102THE ANALYST. 117 Averaging the values given by each separate constituent we get the following : Appear- ance has an average valuation of 2.As a reason for this, in every case except one, we have a yellow or yellow green tint. The smell has been reported as sensible in only one case, and therefore the average is too small to notice. The chlorine has a value of 2.1, and varies very slightly in the different samples from a maximum of 2-6 to a minimum of 1.7. With one exception, phosphoric acid is returned as traces, and therefore takes an average value of 2. Free and saline ammonia varies from -0028, which occurred once in the New River water, to none in the Chelsea water, and the average valuation amounts to only -2. Albuminoid ammonia varies from .00'32, in the Lambeth water to -0010 in the New River, autl gives an average valuation of 5 . Oxjgeu absorbed in two minutes varies from *0010 in the Chelsea water to none in the West Middlesex, and gives an average valuation of 2.Oxygen absorbed in four hours varies from 01250 in the Lambeth to *(1310 in the New River, and gives an average valuation of 1.4. The hardness, which may be taken as 15" before boiling and 4O to 5 O after, gives an The total solids value at 4.2, and the microscopical examination Y'hese 18 analyses give us, therefore, another fair basis on which to estimate the equivalence of the different parts of the scale, and they confirm ?he impression that the oxygen absorbed in two minutes is over valued, and the free ammonia rather under valued. There appears some reason to think, as regards the oxygen absorbed, that the increased temperature at which the determinations are now being made has told more on the figures than was expected.I t is noteworthy that in these swnples the microscopical examination has not shown any serious results, but has 011 thc whole giren satisfactory indication of the character of the water. This table may be considered in another way by selecting the worst waters and comparing their figures. Thus it will be seen that the Southrrark and Vauxhall water for March shows an increased valuation over January in the proportion of 39 to 28. This is accounted for by increases in the ammonia, albuminoid ammonia, oxygen absorbed in two minutes and four hours, hardness and microscopical results, or six different determinations. The West Middleeex for January gives a valuation of 39, and for March of only 29, which is accounted for by changes in the chlorine, nitrates, ammonia, albuminoid ammonia, oxygen absorbed in two minutes, hardness, total solids, and microscopical results, or eight determinations. The Grand Junction shows a valuation of' 39 for March, and 28 for January, a difference accounted for by increases in the chlorine, nitrates, albuminoid ammonia, oxygen absorbed in two minutes and four hours, and hardness, or six determinations in all, The Lambeth water for March hag a valuation of 46, and for May of 28.The difference is accounted for by changes in the chlorine, albuminoid ammonia (which shows a very large difference) oxygen absorbed in two minutes and in four hours (which also shows a very large difference) hardness and total solids, or six digerent determinations, I n the other case there is a greenish brown tint, average valuation of 3.8.iLt 1.5,118 THE ANALYST. The Chelsea supply gives a valuation of 33 for March and 22 for May, and this difference is accounted for by increases in the chlorine, nitrates, albuminoid ammonia, oxygen absorbed in two minutes and four hours, hardness and total solids, or seven determinations. The New River for March shows a valuation of 31, and for May of 24, and this is made up by differences in the chlorine, nitrates, ammonia, albuminoid ammonia, oxygen absorbed in four hours, and hardness, or six determinations in all. Therefore, in no case out of these 18 analyses is this increased condemnation dependent on less than the results of half-a-dozen determintitions. I t is consequently clear that this increased value represents an increase of extraneous impnritj.We will next consider 18 samples from sandstone, &c., which are included in the monthly returns for January, March and May (Table IV). These figures enable us to note another new feature in the valuation scale. The supplies of Vhitehaven and Derby rank according to the scale among the purest of any that have been reported upon in the monthly analyses. The valuation of Whitehaven is 9 for March and May, and of Derby 12 for each month. Looking at the figures in the Whitehaven water in detail, we find that only two determinations in each of the analyses give a valuation exceeding one, viz., the niicroscopical examination, which in both cases show vegetable debris and diatoms, the albuminoid ammonia for March which gives a valuation of 2.1, and the oxygen absorbed in four hours for May, which values at 1.2.Taking now the Derby water, we have four columns of the analyses, viz , the appearance, smell, oxygen absorbed in two minutes, and microscopical examination, which give simply negative results. The highest figures in the valuation are contributed by the hardness, which gives 3.8 and 3.0, and the total solids which show 3.6 and 3.5. The nitrates for March have a valuation of 2.2, and the chlorine for the two months 1.6 and 1-8 respectively. From these analyses I obtain a limit for what may be called unavoidable impurity. It ifi indeed roughly, tho degree of contamination of' the most pure public supplies, and 15 seems a fair figure to take for this.Assuming, therefore, that -10 is adopted as the limit of first class water, and 15 as that of water of cxcepiio?iaZ purity, it will be probable thrt 65 ie a fair limit for a second class water, since it will allow for twice as much c.ctra,izeous contaminatioii. From these exceptionally pure water supplies, I will pass to those slightly more contaminated, taking Manchefiter first. At a glance it is evident that the general supply 01' this town is good, and if the valuation figures are a clear indication, as I contend they are, it is uniform in character. We find that January, March and May show valuations of 21, 23 and 21 respectively, while the intermediate months not included in the table give values of 22. I t is evident that no deductions can be drawn from the variations in the character of this water, but for comparison we will see how it differs from the Whitehaven supply, because although the Manchester water is of good quality, it shows a valuation rather more than twice as high as Whitehaven.The Manchester water was in two cases turbid, and in the third had a yellowish tint in addition to the green; this increases the valuation. In one case there was a peaty smell which also adds a fraction. The chlorine gives an average of -76 as against 037 in the Whitehaven water, or nearly twice 811 much, and shows an increased value of T, Phosphoric I attach great importance to this uniformity.THE ANALYST. I19 acid was present in one case, but absent in both Whitehaven samples. Nitrates shows a very small decrease of - 1 which is more than counter-balanced by the increase in ammonia, which amounts to .5.Albuminoid ammonia shows an increase of 2.4 ; oxygen absorbed in two minutes an increase of 4-5, and in four hours of 5.9, and total solid matter an increase of ' 5 , the microscopical examination showing a decrease. Thus we have nine columns in which the results are somewhat less satisfactory, and only two in which there is any indication of improvement. This gives a fairly conclusive indication that the inoreased valuation-though it certainly cannot be called condemnation-is fairly earned by the water. Assuming 40 to be the limit for first class waters, the water supply of Leeds ranges very close to that number. We find the appearance and smell, phosphoric acid, and nitrates are practically the same as Manchester.The chlorine shows a small diminution of -2 ; ammonia a decrease of 4, and albuminoid ammonia of 1 ; while the oxygen absorbed in two minutes gives an increase of 5.5 ; and that absorbed in four hours an increase of 11 ; the hardness of nearly 1, and the microscopical results of 6 . Now, in this case it is clear that the apparent increase of impurity is due almost entirely to the presence of vegetable matters, which, without doubt, are of a peaty character. If a peaty water is to be passed as satisfactory for a public supply, the con- demnation afforded by the values given to the oxygen absorbed, and to the microscopical results is somewhat too great, but the water is certainly less pure than the Whitehaven and Manchester supplies; and what is of paramount importance, and is so pointed out by the value, is the fact that the water is not properly oxygenated.Going one step further, we take the Bradford water. This also is peaty in character, and as regards its proportion of albuminoid ammonia does not differ to any noteworthy extent from the Leeds supply, but the total valuation runs up considerably. The change is due partly to a change in the colour, partly, though to a small extent, to an increase in the albuminoid ammonia, but very greatly to an increase in the amounts of oxygen absorbed in two minutes and four hours, the former of which shows an increasedvaluation of about 12 and the latter of 25. The hardness and total solids exercise very little influence on the total value.The condemnation here is marked and due almost entirely to the large amount of oxygen absorbed, i.e., to defective aration. Therefore, this water might probably be much improved by mechanical agitation, such as a waterfall, or by the diminution of the growth which possibly exists in the large reservoirs. Taking, therefore, these 18 waters all drawn from collecting grounds supposed to be free from any direct contamination with excreta, and only containing different proportions of peaty and other vegetable matter, the scale is found to be a practical and satisfactory one, and, if it errs at all, it is to make the condemnation of an impure water rather more emphatic, while it brings out in the clearest possible way the purity of such supplies as those of Whitehaven and Derby.But even these three series of analyses are not sufficient in my opinion to fully confirm the value of the scale, and we will consider next some waters taken at random as they have come in for ordinary analysis, four of them being supplies of large towns not included in our monthly reports (Tablc V). These are purposely selected as being on the whole of less satisfactory character, and in order to show the way in which the scale works they are arranged in the order of their values. This renders it easy to view them again from another120 THE ANALYST. point of view, and we will take first the our waters-A, B, C, D-which each show a value of less than 50. A is from a deep well in a district not very largely populated, and shows only one determination (the hardness), which has a valuation exceeding 5 .No figure of the valuation indicates heavy organic contamination, and the water passes well within first class. B is from a shallow well. The proportion of oxygen absorbed shows a higher figure, the other figures of the analyses being fairly identical, except total solids. Passing over the next three analyses as being of little moment except for comparison, I come to C;, H, and J, which give values of 82, 89, and 89. They may fairly be looked at together. The chlorine in each is high, and gives values of 16.4, 16.9, and 16.4 respectively. The valuation for phosphoric acid in one case is eight. The nitrates in J, which is a shallow well in the sandstone, rise to 30, a figure which in itself, without the other details of the analyses being considered, is almost condemnatory.In G the free ammonia values at 22, the albuminoid ammonia in that sample values at 13.8, and in the next at 13.6. The highest value reached by the oxygen absorbed is 10.4 i n J , and the highest value for total solids is 17 in H, which contains 67.3 grains of total solid matter per gallon. The microscopical results acquire no undtie weight, as the highest value is 6. Looking at the three samples as a whole, 20 out of the 36 valuations exceed 5 , and eight of them exceed 10. It will be found as 8 general rule that any single valuation which exceeds 5 is undesirable, and that any valuation which exceeds 10 casts grave suspicion upon a water, and these three analyses bear out that statement very closely.Again, passing over one or two intermediate analyses, we will consider 11, N, 0 , which are all waters from chalk wells comparatively near to the sea-share, but in one case st least (0) inspection on the spot proved that surface drainage from cultivated land and from an adjacent farmyard enter to a considerable extent. I n the other two samples, drainage water from arable land has been proved to find its may into the leaky water tubes. The valuations of these three waters are respectively 198, 218, and 300, and, therefore, if the valuation scale is of any good at all, these .u-aters are unfit to drink. They differ in character very considerably, and afl'ord another and very fair standpoint from which to judge the scale. The appearance in eacb case gives a value of 6.I n M the chlorine has it value of 130, in 0 of 30, and in N of 154. If salt is objectionable in a drinking water, we have it here in such quantity that two of the waters are condemned by the proportions of chloride of sodium, independently of any other constituent in the analyses. These pro- portions, which are 42 grains per gallon in N, and 35 grains in 31, are, of course, quite sufficient to render the water, when warmed, distinctly saline and insipid to the taste. Phosphoric acid is valued at from 4 to 2 in the three samples, and nitrates range as high as 6. Free ammonia in M gets a value of 2.6, while in 0 the albuminoid ammonia shows -0763, and has a value of 143, which is probably quite sufficient in the opinion of every analyst who has ever used the alburninoid ammonia process to condemn the water, ~v]lether a valuation scale be used or not.The oxygen absorbed in four hours in 0, the least saline water of the tlhree, has tt d u e of ~ 0 . 6 , tallying to some extent in its degree of condemnation with thal due to the alburninoid ammonia. The total solids of course show a high value.THE AXALYST. 121 Now these waters, although emphatically condemned, are so condemned on a less number of different items than is the case in some other instances. I n N and M only six columns in each case get a higher value than 5 , and in 0 only eight columns get a higher d u e than that, but against this must be set the fact that we have in each sample one valuation exceeding 130. The condemnation is severe, but surely not unjust for such a tigure as this.One more series of waters I must take for the purpose of comparison, and these are tile Nay waters analysed by the members of the Society, the analyses of which appeared in the dune number of THE ANALYST. I t is unnecessary to go at detail through these, especially n s some have already been referred to, but it is worth while to consider some three or four of the most pure and three or four of the most impure ones, The Bath water for May shows a Faluation of 11, and only twe of the determiiiations m c h 4, viz., the hardness aacl total solids. The scale clearly applies well to that water. The Hull water values at 14, only one figure, the total solids, reaching 4. There is no trace of organic impurity, and that water evidently is justly passed as of first class quality.Llandrindod again gives a total valuation of 10, and only one dttermination, the hardness, exceeds 3 in value. We will now consider three cases where the valuations exceed 50, viz., (heenock, with a valuation of 94 ; King’s Lynn, of 106 ; and Dudley, of 55. Bradford has already been dealt with. Taking Dudley first, the condemnation is based mainly upon the excessive amount of oxygen absorbed in four hours, viz., ,1834, valuing at 20. If the figures stood alone, we might be almost inclined to doubt the desirability of condemning water upon it, but the same determination for March gave 1, which is quite sufficient to show that the water is non- mated, and this result coupled with the other figures is sufficient to take the water out of the possible pale of first class.At Greenock again the condemnation is due more to the proportion of oxygen absorbed than to any other figure, the amount absorbed in four hours reaching *2550, valuing at 41. We have no previous analysis of this water for comparison, and therefore must deal with it on its merits. It is evident that the water is lamentably non-oxygenated, and despite its softness and tolerably moderate amount of nitrogenous compounds, except as albuminoid ammonia, it does not seem at all too strong to say that the water is unfit to be used as the public supply of any town. The King’s Lynn water is valued at 106, and the condemnation is made upon the albuminoid ammonia, with a valuation of 14, and the oxygen absorbed in two minutes and 4 hours with a valuation of 15 and 46 respectively, and every other constituent in the analysis, except the free ammonia, gets a value of from 3 to 4.The water is therefore what may be best described as bad all round. The colour, smell, phosphoric acid, nitrates, albuminoid ammonia, and the microscopical results are all unsatisfactory. Looking at this, therefore, 106 is not a t all too high a condemnatory value for the water which must be described as a bad third class one and unfit to be supplied to any town for drinking water. I think I have now tested the scale as it exists, and is in use in the most exhauative manner practicable within the time at oiir disposal, and it only remains for me to me what dterations are practicable or desirable.The main change necessary certainly seem8 to be in the valuation given to the oxygen absorbed.122 THE ANALYST. When I first proposed the scale three years ago it was not contemplated to maintain the Rater at a temperature of SOo, while the permanganate solution was acting, or to increase the duration of the test. This increase of temperature increases the relative power o f t h e permanganate, and I think the result of the comparison of all the figures shows that, if the valuation for the two minutes determination is allowed in future for the absorption which takes place in 15 minutes instead of 2, a more just opinion on the character of a water will be arrived at. The free ammonia valuation may need increase so as to allow 1 for every a002 grain per gallon, but I prefer at present to leave this unaltered till longer experience shows if it is needed or not.These are the only two alterations which I think really desirable in the chemical part of the scale, but one other point has to be considered. The microscopical examination takes, as at present arranged, a maximum valuation of 10. This value is not high enough to be given to that determination by an analyst in the daily habit of using the microscope, and that and some of the other physical determinations should have an increased value. I , therefore, propose the following amplified scale, as regards the physical tests coupled with the slight amendment of the chemical valuations, which consists in giving the same value to oxygen absorbed in 15 minutes as has been previously taken by that absorbed in 2 minutes.It is, of courm, obvious that the microscopical valuation is merely an outline, the details of which must be subsequently filled up. dppearmee in 2-ft. tube. I give the figures in t4he order in which they appear in our nionthly reports. C. blue .............................................................................. 0 C. pale yellow ..................................................................... 2 C. green .............................................................................. 2 C. dark yellow ..................................................................... 4 C. dark greon ........................................................................ 4 For traces ........................................................................... 1 ,, turbidity ........................................................................ 4 Vegetable matter .................................................................. 1 Strong peaty ........................................................................ 2 Oflensive, of animal matter ...................................................... '1 Chlorine in Chlorides ..........................................................GO grs. per gal. = 1 phosphoric acid as phosphates. Traces ....................................... = 2 h. traces = 4 v. h. traces = 8 Nitrogen in Nitrates ............................................................ -100 gr. per gal. = 1 - 1 Suspended matter to be added to valuation of appearance.,, heavy traces .................................................................. 2 Smell when heated to 1UO" F. Ammonia ........................................................................ ,005 gr. ,, - 1 Albuminoid Ammonia ......................................................... -001 gr. OxJgen absorbed in 15 minutes at 800 Fah. .............................. -002 gr. 11 = 1 13 17 4 hours ,, ,, -010 gr, ,, = 1 Hardness liefore and after boiling added together .......................................... 5" ;= 1 'rota1 Solid Matter ............................................................... 5 grs. per gal. 7 1 ,, .............................. IIeavy Metals ......................................................................... 8. traces == 6 ,, H. ,, = 12 ........................................................................... 9 ?THE ANALYST.125 Microscopical results. Vegetable debris in small quantity ............................................. 4 ,, large ,, ............................................. 8 Diatoms and Bacteria in small quantity ....................................... 6 Hairs, and animal debris ...... 10 to 20, according to the quantity observed, Mr. Wigner concluded by moving (( That a water valuation scale analagous to that which has been suggested be recommended by the Society for the adoption of its members.” Dr. Muter said that, to place the matter fairly before the Society, he thought it very desirable that they should first of all debate the general question, viz. : Were or were they not to have a valuation scale for mater analyses.He himself believed thoroughly in the fundamental principles of such a scale as that so ably put before them that evening by Mr. Wigner, but there might be gentlemen present who did not share that belief, and they would have an opportunity on the present motion of bringing forward their views, and should they be, as he hoped, rejected by the meeting, then it would be desirable to discuss the items of the scale seriatim. He therefore, without further occupy- ing time at that stage of the proceedings, begged to second Mr. Wigner’s motion. Mr, Lyte said no one could fail to be struck with the great meed of truth that there mas in Mr. Wigner’s scale, and the members would, he thought, be inclined to agree that a soale be adopted on that basis.Mr. Thomas moved as an amendment (‘ That it is premature to adopt any fixed water valuation scale at present and that it be not considered.” He said that one of the reasons why he opposed the adoption of the scale was that a peaty water (Bradford water in Table IV.), which he considered a good water, was valued at 65; whereas if one knew the previous history of a water and that was unfavourable, he would have no hesitation in condemning it, although its valuation was below G5. He for one wodd never pledge him- self to use the scale. It was not for the Society to adopt anything, and it was entirely out of harmony with the conetitution of the Society. Mr. Hehner seconded the amendment and said they must first know the history of the waters with which they had to deal, and then apply the scale.If they did not kuow the history the scale was absolutely useless. Water containing a good deal of chlorine would be rejected and yet it might not be a bad water at all. Chlorido of sodium did not do any harm if it were not derived from pollution. He thought it was impossible to adopt a scale unless the analyst knew what water he had under his hand, and if he did know there was no need to adopt any scale. Dr. Dupr6 said he should be sorry to meet the proposal with a direct negative because he was fully convinced that Mr. Wigner had gone into the matter very carefully, and that the valuation scale really on the whole followed very closely what would be the general opinion on a given water. At first sight there appeared to be discrepancies, for instance, the value attached to albuminoid ammonia seemed far too low in any given water.On closer examination it would, however, be found that where the albuminoid ammonia mas high that was never the only thing which was high ; it was always accompanied by certain other constituents that increased the value, and therefore the value of the albuminoid ammonia ~ 8 8 really that of the albuminoid ammonia plus the other constituents that increased $ 7 9 , ,, large ,, ....................................... 12124 THE ANALYST. simultaneously, and therefore he believed the scale had on the whole been remarkably well adjusted. At the same time he was not prepared for the Society to adopt it yet, and should be inclined to propose that the scale be provisionalIy used in the monthly table published in THE ANALYST so that they could see it in print.Mr. Dyer said that in many cases the scale might be valuable, and especially for private use, but he certainly should not like to see the Society pledged to the adoption of any scale. On the amendment being put it was rejected. Dr. Dupr4 then moved as an amendment ‘(That such a scale be provisionally used and that the figures be published with the published water analyses of the Society until the end of this year,” and said he was quite of opinion that it was premature to definitely adopt a scale at present, but he had faith enough in the scale to think that it ought to get a ftiir trial, and it would never get a fair trial unless a number of analyses were published with the values attached.For himself, he had gone into the scale now and then, and WRS convinced there was something in it. He had before expressed his opinion that the scale should be improved by raising the valuation of a particular constituent if accompanied by something else-if for example, albuminoid ammonia were accompanied by a certain proportion of nitric acid, to increase the valuation attached to albuminoid ammonia. The same with chlorine : for a certain amount of nitric acid together with chlorine, increase the ordinary value attached to nitric acid, so that a polluted water would probably come out higher than in the present case. In the case of ammonia, Mr. Wigner had proposed that it should be doubled. He had just had four waters from deep wells, some over 500 feet deep, remarkably pure watcrs as regards albuminoid ammonia and oxygen absorbed, in fact, all but perfect in those respects, but three of them contained something like -08 parts of ammonia, which would alone give a valuation of 70 on the altered scale.I n other words, it would bring what was a really first class water down to a third class one. He thought that showed that the valuation of any particular constitlent should be to some extent governed by the rest of the constituents. I n waters as perfect as these were, thevaluation of ammonia should be very low. If on the other hand, they had a water which showed that it was really a polluted water, the value put on ammonia should be high. The next difficulty was the oxygen absorbed. That also he thought ought to be governed by something beside itself.It was perfectly clear that a water contaminated by animal matter which absorbed a given amount of oxygen should have a very much higher value attached to the oxygen than a peaty water. A peaty water might not be a pleasant water to drink or look at, but no one had a right to say that it was a dangerous water. If by means of the oxygen absorbed they condemned such a water, they laid themselves open to severe and very just criticism. No nitric acid being present the oxygen must be valued low, but with nitrates present it must be valued high. Dr. Tripe, in seconding the amendment, remarked upon the figure 10 being fixed as the maximum valuation of the whole of the microscopical results, including bacteria, infusoria, cotton and other fibres, muscular tissue and epethelial debris, and aaid that if he under- stood aright a peaty water might have a valuation of 80 attached to it because of the The oxygen therefore should be governed by something else,THE ANALYST.1% quantity of oxygen absorbed, and 10 only put for the whole of these evidences of direct sewage contamination. He therefore objected to that number and considered it ought to be enlarged by SO much being given to epithelium, muscular fibre, vibrions, and so on. JIicroscopists could not at present invariably distinguish between some forms of innocent bacteria and those which would cause disease, and yet a valuation of 10 only was given to bacteria which might spread Cyphoid, summer diarrhcra, or some other form of disease.And tlierofore bacteria and other things showing diroct sewage contamination should be valued higher. T)r. Dupri. deprecated putting a prohibitory value to any particular constituent, and doubted very much whether a watw was ever found with bad microscopical results where all the other results were not bad too. Dr. Muter said that were the original motion, which he still urged on their considera- tion, carried, he should have moved the omission at present of any valuation being given to physical characters, such as colour, odour and microscopic appearances, because those must always be a matter of opinion, and he thought that only definite chemical points for which they could get figures should be at present considered.,4t the garno time he was not to be taken as detracting from the importance of these indications in experienced hands. The point from which they ought not, however, to wander 1vas-4~ there to be a scale or not, and he hoped that they would not part without coming to a definite decision on this broad principle, favourable to the adoption of a scale. I-Te did not think that it wag desirable to ask THE ANALYST to take B responsibility, which the Society as tt whole dreaded to assume, and this being the tendency of Dr. Duprd's amendment he could not accept it, but still pressed the original motion of Mr. TiVigner on the notice of the meeting. Mr. Heisch said that as far as he understood Dr. Dupr6 he did not wish the considera- tion of the subject postponed indefinitely, but to have the results of the valuation scale as .zpplied to the waters analysed by the members of the Society publiahed with the analyses every month.He thought that if this weri? done, and analysts would give anything like a definite account of the microscopic cxamination, they would at the end of six months be bettzr able to judge of the scale than at present. He had a very great belief in the value of microscopic ssaminations, not only of the deposit from water but also of the residue of the evaporation of a drop on a slide and was always much guided by these in his estimate of a water, but at present was not prepared to give 8 definite value to each individuai ob,ject found. After some other remarks Dr. Dupr6's amendment was put and lost. The discussion having extended to an unusually late hour, Dr.Tripe then proposed, and Mr. Allen seconded, another amendment, (' Thai the further consideration of the matter be adjourned till the first available meeting in January next." This was carried, and the discussion was adjourned accordingly. INSTRUCTIONS FOR WATER AKALxm.-on page 131 we print a further part of these Instructions.PUBLIC WATER SUPPLIES OF ENGLAND . I*ALCATIOX’ OF THE h.4LTSES PUBLISHED IX THE ANALYST 1CCOBI)ISG T O THE fkALE REFERRED TO I N bht . TvIGNER’S PAPER . BUPPLIE 8 . Kent Co ............... New River .............. East London ............ Southwark and Vnuxliall . . West Niddlesex .......... Grand Junetioii .......... Lambeth .............. Chelsea, ................ Bath .................. Birmingham ............ Bradford ................ Bright on ................ Bristol .................. Cnm bridge .............. Canterbury ............ Croyclon ................ Derby .................. Droitwicli .............. Dudley .................. Edinburgh .............. Exeter ................ Grantham .............. Huddersfield ............ Hull .................... King’s Lynn ............ Leamington ............ Leeds .................. Leicester ................ January . 22 23 45 27 34 26 47 34 30 40 .. .. .. 31 15 32 36 .. .. .. 17 25 17 21 60 28 37 .. February . 42 36 37 42 43 32 48 3 6 34 65 20 29 25 18 37 20 12 33 25 28 25 27 76 30 15 63 .. .. March . 28 31 26 39 25 41 46 31 32 51 27 22 2G 18 28 18 33 . 17 30 16 29 35 23 89 30 61 .. .. April . 30 26 23 32 23 28 27 31 14 32 47 22 27 23 19 19 13 .. .. 40 20 26 23 26 103 26 27 .. 31ay . 32 24 2s 36 21 28 26 22 1 L 35 67 26 29 32 16 20 12 42 55 21 17 25 21 20 106 40 27 .. a I 1 M . 23 18 36 30 31 2; 29 26 11 3 3 58 26 19 29 15 2s 14 .. .. 35 18 30 20 20 131 21 34 3 0 s VPPLIES . Liverpool .............. Llandrindod ............ Maidstone Water Cornpang .. Public Conduit . Mancheater., ............ Newark ................ Newcastle-on-Tyne ...... Norwich ................ Not tiagham ............ Oldham ................ Plymouth .............. Portsmouth ............ Reading ................ Rochdale ................ Rugby .................. Salford ................ Sheffield ................ Shretvsbuiy ............ Southampton ............ Stockport .............. Stourbridge ............ Stourport .............. Sunderland .............. Smanses ................ Warwick ................ Whitehaven ............ Wolverhampton .......... Worcester .............. January . .. .. .. .. 21 37 36 34 .. .. .. .. .. .. .. 12 22 22 .. .. .. .. 65 36 .. .. .. .. Febrnary . 3 7 18 .. .. 26 GO 40 37 .. .. 38 37 37 .. .. 12 25 37 34 3s 32 28 16 13 (i 5 6 4 .. .. 4 1 11 19 13 23 39 40 26 31 36 23 30 21 20 24 50 14 30 23 24 12 31 10 49 61 .. .. .. April . 36 34 32 28 26 34 23 50 20 18 29 25 9 35 27 20 20 39 20 .. .. .. 23 17 4 37 48 .. Xny . 31 10 30 30 21 32 33 48 47 15 20 20 10 42 18 20 20 41 18 44 26 24 21 37 7 35 47 .. . June . 34 42 40 19 38 32 32 .. .. .. 0 I 27 20 8 58 21 .. ia 50 .. .. .. .. 12 11 42 .. ..

ISSN:0003-2654    

DOI:10.1039/AN881060111b

出版商:RSC    

年代:1881

数据来源: RSC

摘要:

THE ANALYST. 127 THE ANALYSIS OF THE PUBLIC WATER SUPPLIES OF ENGLAND.* INSTRUCTIONS FOR WATER ANALYSIS. Prepared by a Committee appointsd by the Society of Public Analysts. WHEN the Society of Public Analysts arranged to publish monthly analyses made by its members of the water supplies of the leading towns in the kingdom, they con- templated the possibility of bringing about more general agreement than had formerly been practicable in the processes used, and the modes of reporting results. The scheme proposed has met with marked acceptance among analysts who, no doubt, in many cases may have reason to prefer other methods, but who have given way in favour of a system which appears to concern the goneral good of the profession, and to be for the public advantage. This concord of opinion has already rendered it necessary to print a secoud edition of the instructions for water analysis, which were issued to the analysts engaged ; and a third, but more detailed edition, is now called for.To answer the requirements of those who have been in correspondence with the Secretaries on the subject, this third edition contains such full and explicit details as will enable any competent analyst to execute a water analysis in such a way as to make the results directly comparable with those obtained by any other analyst working under these instructions. The instructions do not take the form of an elementary treatise on water analysis, but they specify the essential details of the manipulation in such a way as to be intelligible to a skilled analyst. The Water Committee of the Society has not been free from difficulty in the duty which it has undertaken, as it was only possible to adopt processes the details of which were such as could be carried out with ease and uniformity by the great body of analysts.On this account some matter in itself valuable has necessarily been omitted, such as the estimation of organic carbon and nitrogen, the instructions for more complete microscopical examina- tions, and Messrs. Crookes, Odling and Tidy’s method for taking the colour of water. The Committee has freely availed itself of published works and papers on water analysis, and has, as far as possible, tested every reported process, whether contained in the well-known treatises on the subject, or in the various papers contributed to their own and other Societies.The method of reporting the results in grains per gallon has been adopted after very careful and mature considoration. The Committee are well aware that if reports were made in parts per 100,000, they would be equally intelligible to analysts generally, but they cannot overlook the fact that these reports have in many cases to pass into the hands of those to whom a statement in parts per 100,000 is more or less unintelligible. The instructions are worded in such a way that analysts can use either the English or the metric system of weights and measures for their own work, and can prepare their standard solutions according to either system, simply making their reports uniform by the adoption of the English figures. The tables of aliquot parts of a gallon, and factom, which are included in the instructions, will facilitate the necessary calculations. * It having been decided to publish the new edition of the Instructions for Water Analysis in THE ANALYST, we have arranged to page the monthly divisions so that the whole will bind up together when completed.

ISSN:0003-2654    

DOI:10.1039/AN8810600127

出版商:RSC    

年代:1881

数据来源: RSC

摘要:

THE ANALYST. THE PREPARATION OF REAGENTS. A,-REAGENTS FOR THE ESTIMATION OF CHLORINE. NOTE.-AZZ solids art3 to bs weighed and liquids measursd. (a) Standard Solution of Silver Nitrats- Dissolve 4,7887 parts of pure recrystallised silver nitrate in distilled water, and make The solution is to be standardized against the -001 the solution up to 1000 parts. standard solution of sodium chloride, and adjusted if necessary : 1 C.C. gramme of chlorine, or 10 grains = 001 grain chlorine. ( b ) Standard Solution of Sodium Chloride- Dissolve 1.648 parts of pure dry sodium chloride in distilled water, and make the solution up to 1000 parts. 1 C.C. solution contains -001 chlorine, or 10 grains contain ~ 0 1 grain chlorine, The pure sodium chloride is best prepared b.y taking a saturated solution of best commercial sodium chloride, filtering it cold, and passing a current of HCl.gas into it. The gas prodaces a fine crystalline precipitata of pure sodium chloride, which must be washed rapidly with cold water and dried at about 500° to 600° F. ( u ) Potassium Monochromate- 50 parts of potassium monochromate are dissolved in 1000 parts of distilled water. A Mot? y bdic One solution of silver nitrate is added until a permanent red precipitate is produced, which is allowed to settle. Solution- part pure molybdic acid is dissolved in 4 parts ammonia, sp. gr. -960. This solution, after filtration, is poured with constant stirring into 15 parts of nitric acid of 1.20 sp. gr. I t should be kept in the dark and carefully decanted from any precipitate which may form.B.-REAGENT FOR THE ESTIIEATION OF PHOSPHORI~ Aa~n. C. REAGENTS FOR THE ESTIMATION OF NITROGEN IN NITRATES. Solution of Silver Sulphate- A saturated solution of silver sulphate in distilled water. Concentrated 8ulphzsric Acid- In order to ensure freedom from oxides of nitrogen, this should be kept in a bottle aon- Metal 1 ic A lumanium- As thin foil. Solution of Sodium Hydrate- Dissolve 100 parts of solid sodium hydrate in 1000 parts of distilled water. When cold, introduce a strip of about 100 square cms., say 15 square incches, of aluminium foil previously heated to just short of redness, wrapped round a glass rod. When the aluminium is dissolved, boil the solution briskly in a porcelain basin until about one-third of its volume has been evaporated, allow it to cool, and make it up to ite original volume with water free from ammonia. The solution must be tested by a blank experiment to prove the absence of nitrates. taining mercury, and agitated from time to time, which will ensure their absence.Broken Pumice- Clean pumice broken into pieces of the size of small peas, raifted free from duet, heated to redness, and kept in a olosely stoppered bottle.THE ANALYST. 129 1 Hydrochloric Acid free from Ammonia- If the ordinary pure acid is not free from ammonia, it should be distilled. As only two or three drops are used in each experiment, it will be sufficient if that quantity does not contain an appreciable proportion of ammonia. Copper Sulpha te Solution- Dissolve 30 parts of pure copper sulphate in 1000 parts of distilled water.Metallic Zinc- As thin foil. Standard Solution of Ammonium Chloride-(see D a). Nessler’s Solution--(see D b ) . This should be kept in a dry atmosphere, so as to be preserved as far as possible from oxidation. D.-REAGENTS FOR THE ESTIMATION OF NITROGEN AS AMMONIA AND ALBUMINOID AMMONIA. Standard Solution of A vtinzonium Chloride. Dissolve 5.146 parts of pure ammonium chloride in 1000 parts of distilled water free For u ~ e , dilute this with pure distilled water to ten times its bulk. Nessler Solution I) Dissolve 35 parts of potassium iodide in 100 parts of water. Dissolve 17 parts of mercuric chloride in 300 parts of water. The liquids may be heated to aid solution, but if so must be cooled. Add the latter solution to the former until a permanent precipitate is produced.Then dilute with a 20 per cent. solution of sodium hydrate to 1000 parts ; add mercuric chloride sclution until a permanent precipitate again forms; allow to stand till settled, and decant off the clear solution. The bulk should be kept in an accurately stoppered bottle, and a quantity transferred from time to time to a small bottle for use. The solution improves by keeping. from ammonia. Sodium Carbonate. A 20 per cent. solution of recently ignited pure sodium carbonate. Potassium Permanganate Solution. Dissolve 200 parts of potassium hydrate and 8 parts of pure potassium permanganate in 1100 parts of distilled water, and boil the solution rapidly till concentrated to 1000 parts. Distilled Water which is free from Ammonia, Distilled water which gives no reaction with Nessll r test is pure enough.But, if this ie not available, take the purest distilled water procurable, add pure ignited aodium carbonate in the proportion of one part per 1000, and boil briskly until at least one-fourth has been evaporated. E. REAGENTS FOR THE ESTIMATION OF OXYoEN ABIORBED. Standard Solution of Potassium Permanganate- Disgolve -395 parts of pure potassium permanganate in 1000 of water. Eaah 0.6. contains *0001 gramme available oxygen, and each one grain contains *0001 grain. Potassium Iodide Solution- One part of the pure salt re-crystallized from alcohol, disrrolved in 10 parts distilled Diluta Sulphuric Acid- One part by volume of pure snlphnric acid irs mixed with three parts by volume of water.I30 THE ANALYST.distilled water, aad solution of potassium permanganate dropped in until the whole retains il very faint pink tint, after warming to 80° F. for four hours. f d ) Sodium H?yposu lphit e- (e) Starch Wuter- One part of crystallized sodium hyposulphite dissolved in 1000 parts of water. One part of starch to be intimately mixed with 500 parts of cold water, and the whole REAGENTS FOR THE ESTIMATION OF HARDNESS. Diseolve eight grains of pure crystallized calc spar in dilute hydrochloric acid in a platinum dish, adding the acid gradually, and taking precautions to prevent loss by spurting. When all is dissolved, evaporate to dryness in a water-bath, add a little distilled water and again evaporate to dryness. Repeat several times to ensure the expulsion of all the acid.Lastly, dissolve in water and make up to one- tenth of a gallon. For use : dilute to 10 times its volume, the result will be water of So of hard- ness. Or, instead of making the solution thus, dissolve 1.376 grains pure crystallized selenite in i'nth gall. water, and that will be the water of 8Q of hardness. briskly boiled for five minutes, and filtered, or allowed to settle. F. ( a ) Standard S'olution of Calcium Chloride- ( b j Standard So~zp Sohtion- Take 150 parts lead plaster (Eniplastrum P h i l ~ b i P.B.), rub in a mortar with 40 parts dry potassium carbonate ; when fairly mixed add absolute alcohol which has been standing over potassium carbonate for a few days. When solution is complete, filter and add sufficient recently boiled distilled water to reduce the alcohol to the strength of proof spirit.The solution of soap must then be reduced to the proper strength with proof spirit made by mixing recently boiled distilled water with the absoliite alcohol prepared as directed above. I t should be of such strength as just to form a permanent lather, when 180 grain measures are shaken with 1000 grains of a solution of lime of 8" hardness. The following table will then give the degrees of hardness corresponding to the number of grain measures employed : Hardness. Grain Measures. Hardness. Grain Measures. O0 9 *.. 5 O 120 lo 29 ... 6 O 140 2" 54 ... 7O 160 30 77 ... 180 4O 99 ... After which I degree=20 grain measures. This is the last solution recommended by Dr. Clarke, tbe one referred to in his patent not being quite accurate.COLLECTION OF SAMPLES.-AI~ samples of water for analysis must be collected in stoppered glass bottles which have been cleaned by successive rinsings with acid and water. A Winchester quart will suffice. Stoneware bottles must not be used. Each bottle must be filled with the water to be sampled, andemptied, before the sample is taken for analysis. The bottle must then be filled to the neck, stoppered, and tied down. Each report should specify the place where, and the date and time when, the sample wag drawn. Wherever practicable, it is desirable to report the temperature of the water at the time the sample was taken, and also to observe whether the water when collected is clear or not. For an accurate analysis of a public water supply, it is essential that the sample should not be drawn from a cistern; a public stand-pipe, cab rank, or fire hydrant, is generally the most satisfactory place from which to take a sample ; but, failing this, the ball-cock of a cistern is a permissible source.It is desirable to avoid drawing stagnant water from a pipe or dead main, and it is especially necessary to avoid aerating the water in the act of filling the bottle. 1.'L'HE; ANAliY ST. 131 2. APPEARANCE IN %FOOT TuBE.-Thecolour or tint of the water must be ascertained by examination in a tube 2 feet long and 2 inches in diameter. This tube should be mado of glass as nearly colourless as may be, and should be covered at each end with a disc of' perfectly colourless glass cemented on, an opening being left for filling and emptying the tube.This opening may be made either by cutting a small segment off the glass disc a t one end or by cutting a small segmental section out of the tube itself before the disc is cemented on. These tubes are most conveniently kept on hooks in a horizontal position to prevent the entrance of dust. The tube must be about half filled with the water to be examined, brought into a horizontal position level with the eye, and directed towards a well illuminmted white surface. The comparison of tint has to be made between the lower half of the tube containing the water under examination, and the upper half containing atmoapheric air only. 3. SMmL.-Put not less than 3 or 4 ounces of the water into a clean &ounce wide-mouth stoppered glass bottle which has been previously rinsed with the same water.Insert the stopper and warm the water in a water-bath to IOO* F. (38" (3.). Remove the bottle from the water-bath, rinse it outside with good water perfectly free from odour, and shake it rapidly for a few seconds ; remove the stopper, and immediately observe if the water has any smell. When the water has a distinct odour of any known or recognized polluting matter, sacb a8 peat or sewage, it should be so described ; when this is not the case, the smell must be reported simply as Gone, very slight, slight, or marked as the case may be. CHLoRINE.-This is to be calculated as chlorine, and returned under the heading of '' Chlorine in Cblorides." Titrate at least 100 C.C. or 1,400 grsins of the water with the standard silver nitrate solution, either in a white porcelain basin or in a glass vessel standing on a porcelain slab.using potassium chromate as an indicator. The titration is conducted as follows: The sample of water is measured into the basin or beaker, and 1 C.C. or 15 grains of potassium chromate solution added. The standard silver nitrate solution is then run iu cautiously from a burette until the red cnlour of tho precipitated chromate of silver, which is always observed at the point where the silver solution. drops in, is no longer entirely discharged on stirring. The burette is then read off. It is best to repeat the experiment, as follows : Add a few drops of dilute sodium chloride solution to the water last titrated, which will discharge the red colour.Measure out a fresh portion of the water to be titrated into another basin and repeat the titration, keeping the first sample, the colour of which has been discharged, side by side with the second, so as to observe the first permanent indication of diference of colour. If the quantity of chlorine be so small that still greater accuracy is necessary, the titration may be conducted in the same way as last described, but instead of the operator looking directly a t the water containing the chromate solution, he may place between the basin containing the water and his eye a flat glass cell containing some water tinted with the potassium chromate solution to the same tint as the water which is being tested, or may look through a glass coated with a gelatine film coloured with the same salt.Care must always be taken that the water is 8s nearly neutral as possible before titration. If originally acid it should be neutralized with precipitated carbonate of lime. If the proportion of chlorine be less than * 5 grain per gallon, it is desirable to take a larger quantity of the water, say 250 C.C. or 5,500 graina, Insert the stopper again and repeat this test. 4.132 THE ANALYST. for the estimation, and to concentrate this quantity on the water-bath before titrating it so as to bring it to about 100 C.C. or 1,400 grains. This titration may be performed by gaslight. PHOSPHORIC AcID.-This is to be returned under the heading of “Phosphoric Acid in Phosphates.” The ignited total residue, obtained as hereafter directed, is to b e treated with a few drops of nitric acid and the silica rendered insoluble by evaporation to dryness. The residue is then taken up with a few drops of dilute nitric acid, some water is added, and the solution is filtered through a filter previously washed with dilute nitric acid.The filtrate, which should measure 3 C.C. (or say 50 grains), is mixed with 3 C.C. of molybdic solution, gently warmed, and set aside for 15 minutes at a temperature of 800 F. The result is reported as ‘L traces,” ” heavy traces,” or “very heavy traces,’’ when a colour, turbidity, or definite precipitate are respectively produced, after standing for 15 minutes. 6. NITROUEN IN NITRATES.-This should be determined by one or other of the follow- ing processes, viz., Crurn, Copper-zinc or 14Zuminiuin.Analysts should report which process is employed. (Jrum Process.-This should be carried out in a Lunge’s nitrometer as follows :- 250 C.C. or &th gallon of the water must be evaporated to a smail bulk, the chlorine precipitated with solution of silver sulphate, filtered and concentrated in a basin to 2 C.C. or 30 grs. measure. A Lunge’s nitrometer is charged with mercury, and the S way stop-cock closed, both to measuring tube and waste pipe. The concentrated filtrate is poured into the CUP a t the top of the measuring tube, and the vessel which contained it rinsed with 1 C.C. of water, and the contents added. The stop-cock is opened to the measnring tube, and, by lowering the pressure tube, the liquid is sucked out of the cup into the tube.The basin is again rinsed with 5 C.C. of pure strong sulphuric acid, and this is also transferred to the cup and snckcd into the measuring tube. The stop-cock is once more closed, and 12 C.C. more sixlphuric acid put into the cup, and the stop-cock opened to the measuring tube until 10 C.C. of acid have passed in. The excess of acid is discharged, and the cup and waste pipe rinsed with water. Any gas which has collected in the measuring tube is expelled by opening the atop-cock and raising the pressure tube, taking care no liquid escapes. The stop- cock is closed, the measuring tube taken from its clamp and shaken by bringing it slowly to a nearly horizontal position and then suddenly raising it to a vertical one. This shaking is continued until no more gas is given off, the operation being, as tt mle, quite complete in fifteen minutes.Now prepare a mixture of 1 part of water with 5 parts of sulphuric acid, and let it stand to cool. After an hour, pour enough of this mixture into the pressure tube to equal the length of the column of acidulated water in the working tube, bring the two tubes side and side, raise or lower the pressure tube until the merciary is :kt the same level in both tubes, and read OE the volume of the nitric oxide. This volume expressed in c.c.’s and corrected to normal temperature and pressure gives, when multiplied by -175, the nitrogen in nitrates, in grains per gallon, if 250 c.e. of the water have been used. According to some authorities the precipitation of the chlorides is not necessary.Qopper-Zinc Process.-This must be carried out, as follows :-A wet copper-zinc couple is prepared by taking a piece of clean zinc foil, about 3 in. by 2 in., and immersing it in a solution of copper sulphate, containing about 3 per cent. of the pure crystallized salt. A copious and firmly adherent coating of black copper is speedily deposited upon the 5.THE ANALYST. 133 surface of the zinc, which must be allowed to remain in the solution until the deposit is thick enough, but not for too long time or it will become pulverulent and not adhere firmly to the zinc-three or four minutes will generally be sufficient. The zinc coated with copper must then be removed from the solution, which may be bottled for subsequent use, and the couple ihoroughly washed first with distilled water, and finally with the water to be ana!ysed, in order that this may replace the adhering distilled water.I t is then put into a clean 6 or 8-ounce wide-mouth stoppered glass bottle and covered with the water to be analysed, which may be 3 or 4 ounces or more in quantity. If the water be very soft a small addition, say one part per 1000, of sodium chloride, will accelerate the reaction. The stopper must then be inserted in the bottle and the water allowed to remain overnight in a warm place. If still greater speed be necessary the temperature may be raised to 90° or 100° F. (32' or 38O 0.). With hard water it is preferable to add a small quantity of pure oxalic acid to precipitate the lime and quicken the reaction. On the following morning, the conversion of the nitrates into ammonia will be complete, and the proportion of ammonia formed must be estimated in one of the two following ways according to the character of the water.If the water be suficiently tinted to show a perceptible colour in the Nessler glass, or if it contains magnesium salts or other substances capable of being precipitated by the Nessler reagent, a measured portion of the sample after treatment with the copper-zino couple must be distilled and the distillate nesslerized as hereafter described. If the water is not tinted, and does not contain any other substance that would interfere with the delicate action of the Nessler reagent, it mag be nesslerized direct. I t will some, times be necessary to dilute tho water considerably before nesslerizing in order to enable the reading to be accurately taken.Ammonia foiind must be calculated to nitrclgsn, and not to ammonia, as in the neselerizing of the ammonia distillates. The nitrogen, present as ammonia, must of course be deducted from the proportion found. If any doubt exists as to the completion of the reaction, this map be ascertained by testing for nitrous acid, by adding a small quantitly of a solution of metaphenglene diamine to a portion of the fluid acidified with sulphuric acid. A yellow colour will be produced in a few minutes if nitrous acid be present. .ilunainiiiru Process.-This is carried out as follows :--50 C.C. or 1000 grains of the water are introduced into a retort, and 50 C.C. or 1000 grains of a 10 per cent. solution of caustic soda, free from nitrates added.If necessary, the contents of the retort should be distilled until the sample is free from ammonia. The retort is then cooled and a piece of aluminium foil introduced into it. The neck of the retort is inclined upwards and its mouth closed with a perforated cork, through which passes the narrow end of a small chloride of calcium tube filled with powdered pumice or glass beads wetted with very dilute hydrochloric acid free from ammonin. This tube is connected with a second tube containing pumice stone moistened with strong sulphuric acid, which serves to prevent any ammonia from the air entering the apparatus, which is a.llowed to stand in this way for a few honrs or overnight. The contents of the first absorption tube-that next the retort-are waahed into the retort with a little distilled water free from ammonia, and the retort adapted to a condenser.The contents of the retort are distilled to about half their original volume. The distillate is collected and an aliquot part nesslerized ; and, if necessary, the rest of the distillate is diluted, and an aliquot part again nesslerized as hereafter directed. If none be present the reaction is complete.134 THE ANALYST. 7. AMMONIA FREE AND ALBUMINOID.-The estimation of ammonia present in the water in a free or saline form, and of that yielded by the nitrogenous matter present in the water (commonly called albuminoid ammonia), is to be made on the same portion of the sample to be analyed. Take not less than 500 C.C. or 7000 grains (one deci-gallon) of the water for theae determinations, and distil in a 40 oz.stoppered retort, as this is large enough to prevent the probability of portions of the water being spurted over into the condenser. The neck of the retort should be small enough to pass three or four inches into the internal glass tube of a Liebig’s condenser. If the fit between the retort and the inside tube of tho condenser is good, the joint may be made by wrapping a small piece of Fashed tinfoil round the retort tube so as to pass just inside the mouth of the condenser tube. Many analysts prefer, h0m.e:-er, to work with a retort fitting loosely into the condenser ; and in such cases the joint between the two may be made in one of the two following ways :-1st. either by an ordinary indiarubber ring-such as those used for the tops of umbrellas-which has been previously soaked in a dilute solution of soda or potash-being stretched over the retort tube in such a position that when the retort tube is inserted in the condenser it shall fit fairly tightly within the mouth of the tube about half an inch from the end; 2nd, prefer- ably, when the shape of the large end of the condenser admits of it, by a short length, say not more than two inches, of large size indiarubber tubing, which has been previously soaked in a dilute solution of soda or potash, being stretched outside both retort tube and condenser tube, so as to couple them together, so that the tube of the retort still projects some inches into that of the condenser.I t is very desirable to have a constant stream of water round the condenser whenever it can be obtained.Before distillation a portion of the water must be tested with cochineal in order to ascertain if it shows an alkaline reaction. The portion SO tested must, of course, be rejected and not put into the retort, If the water does not show an alkaline reaction, a sufficient quantity of ignited sodium carbonate, to render the water distinctly alkaline, must be added. The distillation should then be commenced, and not less than 100 c.c., or, say, 1400 grains, distilled over. The receiver should fit closely, but not air-tight, on to the condenser. The distillation should be conducted as rapidly as is compatible with a certainty that no spurting takes place. After 100 c.c., or, say, 1400 grains, have been distilled over, the receiver should be changed, that containing the distillate being stoppered to preserve ‘ it from access of ammoniacal fumes.The distillation must be continued until 50 c.c., or, say, 700 grains, more are distilled over ; and this second portion of the distillate must be tested with Nessler’s reagent to ascertain if it contains any ammonia. If it does not, the distillation for free ammonia may be dis- continued, and this last distillate rejected ; but, if it does contain any, the distillation must be continued still longer, until a portion of 50 c.c., or, say, 700 grains, when collected, shows no colouration with the Nessler test. The whole of the distillates must be nesslerized as follows :-The standard solution for comparison must be such that it contains a317 parts per ten thousand of chloride of ammonium (= one part of ammonia in 100,000).The distillate is transferred to a clean Nessler glass, and one-twentieth of its volume of Nessler solution added. The Nessler solution must be clear and of a pale straw tint, when seen in an 8-oz. bottle. No tnrbiditymust ensue on the addition of the Nessler solution to the water, as such turbidity would be a proof that the distillate was contaminated, and must, therefore, be rejected, and the determination repeated. 100 C.C. measuring flasks make convenient receivers.THE ANALYST. 185 After thoroughly mixing the water and Nessler solution in the glass, an approximate estimate can be formed of the amount of ammonia present by the amount of colonration produced in the solution.I t will now be necessary to mix one or more standard solntiong with which to compare the tint thus obtained. These solutions must be made by mixing the standard solution of chloride of ammonium with distilled water absolutely free from. ammonia, and subsequently adding some of the same Nessler solution as was previously added to the distillate. This precaution is essential, because the tint given by different samples of Nessler solution varies. A colorimeter may be used, if preferred, instead of Nessler glasses. As soon as the distillation of the free ammonia has been started, the alkaline solution of permanganate of potash should be measured out into a flask ready for addition to the water under examination for the distillation of the albuminoid ammonia.The volume of the alkaline permanganate solution to be taken must be at least one-tenth of that of the water which is being distilled, and should not exceed that proportion unless the water is of very bad quality, and the solution must be made in accordance with the directions contained in these instructions. This solution must be diluted with four times its own volume of water, and must be placed in a flask and boiled during the whole time that the distillation of the sample for free ammonia is being carried on, care being taken that the concentration does not proceed to too great an extent. There must be enough of this boiled and dilated alkaline permanganate solution to make up the residue in the retort to about 500 C.C. or 7000 grains.When the distillation of the sample of water for free and saline ammonis is completed, the alkaline permanganate solution which has been thus diluted and boiled will be ready for use, and the distillation for albuminoid ammonia may be proceeded with as follows :- To the residue left in the retort from which the free ammonia has been distilled, add the alkaline permanganate solution to make it up again to a volume of at least 500 c.c., or say 7000 grains, and the lamp being replaced, the distillation must be continued, and successive portions of the distillate again collected in precisely the same way as during the process of distillation for free ammonia. After 200 C.C. or 3000 grains, gay two-fifths of the volume contained in the retort have been distilled over, the receiver should be changed, and further portions of 60 c.c., or 700 grains, collected separately, until the distillate is practically free from ammonia.The distillates must then be mixed, and nesslerized in the same way as previously directed for free ammonia. The result so obtained must be calculated to ammonia in grains per gallon, and returned as albuminoid ammonia. Special care must be taken that the atmosphere of the room in which these diatillationg are performed is kept free from ammoniacal vapours, and that the receivers fit clo~e, but not airtight, to the end of the Liebig’s condenser. It is also specially necessary to observe that the colour of the distillate deepens gradually after the addition of the Nessler re-agent, and that it is not possible to read off the amount of colour correctly until the nesslerized liquor has stood for at least three minutes, and been intimately mixed with the Nessler solution.Special care must be taken that the retort, condensers, receivers, funnels, Nesaler glasses, &c., used are all rendered perfectly free from ammonia before use. Where the water in use in the laboratory is good, this may be used to thoroughly rinse the apparatue two or three times, draining out the adhering water ; otherwise pure distilled water186 THE ANALYST. be used. These ammonia and albnminoid ammonia determinations should be made as soon as possible after the water hfis been received for analysis. OXYGEN ABSORBED.-TWO separate determinations h y e to be made, viz., the amount of oxygen absorbed during 15 minutes, and that absorbed during four hours; both are to be made at a temperature of 80° F.It is most convenient to make these determinations in 12-oz. stoppered bottles, which have been rinsed with sulphuric acid and then with water. Put 250 C.C. or 3,500 grains into each bottle, which must be stoppered and immersed in a water-bath or suitable air-bath until the temperature rises to 804 F. Now add to each bottle 10 C.C. or 100 grains of the dilute sulphuric acid, and then 10 C.C. or 100 grains of the standard potassium permanganate solution. Fifteen *minutes after the addition of the potassium permanganate, one of the bottles must be removed from the bath and two or three drops oE the solution of potassium iodide added to remove the pink colour.After thorough admixture, run from a burette the standard solution of sodium hyposnlphite, until the yellow colour is nearly destroyed, then add a few drops of starch water, and oontinue the addition of the hyposulphite until the blue colour is just discharged. If the titration has been properly conducted, the addition of one drop of potassium permanganate solution will restore the blue colonr. At the end of four hours remove the other bottle, add potassium iodide, and titrate with sodium hyposulphite as just described. Should the pink eolour of the water in the bottle diminish rapidly during the four hours, further measured quantities of the standard solution of potassium permanganate must be added from time to time so as to keep it markedly pink. The hyposulphite solution must be standardized, not only at first, but (since it is liable to change) from time to time in the following way:-To 250 C.C.or 3500 grains of pure redistilled water add two or three drops of the solution of potassium iodide, and then 10 C.C. or 100 grains of the standardized solution of potassium permanganate. Titrate with the hyposulphite solution as above described. The quantity used will be the amount of hyposulphite solution correbponding to 10 C.C. or 100 grains as may be of the standardized potassium permanganate solution, and tho factor so found must be used in calculating the results of the hypoaulphite titrations to show the amount of the standard permanganate solution used, and thence the amount of oxygen absorbed. The difference between the quantity of hyposulphite used in the blank experiment and that used in the titration of the samples of water multiplied by the amount of available oxygen contained in the permanganate added, and the product divided by the volume of hyposulphite corresponding to the latter is equal to the amount of oxygen absorbed by the water. water in an accurately stoppered 8 oz.bottle. Run in the soap solution from a burette in small quantities at a time. If the water be soft not more than 1 C.C. or 10 grains at a time, if hard, in larger quantities at first. After each addition, shake the bottle vigorously for about a quarter of a minute. As soon as a lather is produced, lay the bottle on its side after each addition, and observe if the lather remains permanent for five minutes.To ascertain this, at the end of five minutes, roll the bottle half-way round; if the lather breaks instead of covering the whole surface of the water, it is not permanent; if it still covers the whole surface, it is permanent: now read the burette. Repeat the experiment, adding the full quantity of soap solution employed in the first experiment, less about 2 C.C. or 20 grains; shake as before, add soap solution verygradually 8. 9. HARDNESS BEFORE AND AFTER BoILING.-Place 100 C.0. or 1000 grains of theTHE ANALYST. 157 till the permanent lather is formed: read the burette, and take out the corresponding hardness from the table. If magnesian salts are present in the water the character of the lather will be very much modified, and a kind of scum (simulating a lather) will be seen in the water before the reaction is completed, The character of this scum must be carefully watched and the soap test added more carefully, with an increased amount of shaking between each addition.With this precaution it will be comparatively easy to distinguish the point when the false lather due to the magnesian salts ceases, and the true persistent lather is produced. If the water is of more than 16O of hardness, mix 50 C.C. or 500 grains of the sample with an equal volume of recently boiled distilled water which has been cooled in a closed vessel, and make the determination on this mixture of the sample and distilled water. In this case it will of course be necessary to multiply the figures obtained from the table by 2.To determine the hardness after boiling, boil a measured quantity of the water in a flask briskly for half-an-hour, adding distilled water from time to time to make up for loss by evaporation. It is not desirable to boil the water under a vertical condenser, as the dissolved carbonic acid is not so freely liberated. At the end of half-an-hour, allow the water to cool, the mouth of the flask being cloaed; make the water up to its origins1 voIume with recently boiled distilled water, and, if possible, decant the quantity necessary for testing, If this cannot be done quite clear, it must be filtered. Conduct the test in the same manner as described above. The hardness is to be returned in each case to the nearest half degree. 10. TOTAL SOLID MATTERS.-Evaporate 250 c.c., or, say, 3fth gallon, in a weighed platinum dish on a water-bath, dry the residue at 220°F., and cool under a dessicator; weigh the dish containing the residue accurately, and note its colour and appearance and especially whether it rapidly increases in weight; return to the water-bath for half-an-hour and reweigh until it ceases to lose weight, then gradually heat it to redness, and note the changes which take place during this ignition. Especially among these changes should be observed the smell, scintillation, change of colour, separation of more or less carbon, and partial fusion, if any.The ignited residue is to be used for the estimation of phosphoric acid as before directed. 11. MICROSCOPICAL EXAMINATIDN OF DmosIT.-The most convenient plan of collecting the deposit is to place a circular microscopical covering glass at the bottom of a large conical glass holding about 20 om.The glass should have no spout, and should be ground smooth on the top. After shaking up the sample, this vessel is filled with the water covered with a plate of ground glass and set aside to settle. After settling, the supernatant water is drawn off by a fine syphon, and the glass bearing the deposit lifted out, either by means of a platinum wire, which should have been previously passed under it, or in some other convenient way, and inverted on to an ordinary microscopical slide for examination. It is desirable to examine the deposit first by a ith and then by a ;th objective. The examination should be made as soon as the water has stood overnight.If the water be allowed to stand longer, organisms peculiar to stagnant water may be developed and mislead the observer. Particular notice should be taken of bacteria, infusoria, ciliata or flagellata, disintegrated fibres of cotton, or linen, or epithelial debris. It is particularly desirable to report clearly on this microscopical examination, not merely giving the general fact that organisms were present, but stating as specifically as possible, the names or classes of the organisms, so that more data may be obtained for the application of the examination of this deposit to the characters of potable waters. It is also desirable to examine the residue left on a glass slide by the evaporation 01138 THE ANALYST. a single drop of the water. This residue is generally most Gonveniently examined without a covering glass. The special appearances to be noticed are the presence or absence of particles of organic matter, or organised structure, contained in the crystallized forms which may be seen, and also whether any part of the residue left, especially at the edges, is tinted more or less with green, brown, or yellow, In connection with the microscopical examination it will also be desirable to adopt the sugar process, described by Mr.Heisch, as follows :- 12. SUGAR TEsT.-The name of this process relates simply to the reagent which is used, namely, pure crystallized sugar. It is believed to be a test for the presence of the germs or spores of the sewage fungus. This special form of fungus grows very rapidly in water containing even a small admixture of sewage water, especially if sugar be present.I t grows as well in a closed bottle of the liquid being tested, as in water exposed to the air, and even better in an atmosphere of carbonic acid. To apply the test: Take a 5-ounce stoppered bottle which has been thoroughly cleaned and rinsed with the water to be tested. Fill with the water to be examined, add about 10 grains or say -5 grammes of crystals of pure sugar, insert the stopper, and put the bottle in a good light, keep it at a temperature of as nearly as possible SOo F. The water should be free from suspended matters before the experiment is made, The bottie must be carefully examined after two or three hours, and again if necessary at intervals. The fungus appears first in the form of minute floating white specks which are generally easily visible to the naked eye in a good side light when the bottle is looked at against a black background.If any suspected speck is seen it must be caught by a fine pipette and transferred to a glass slide, covered, and examined with a a objective and B eyepiece. When first seen, these specks are found to consist of small isolated cells with a bright nucleus. The bright nucleus is still seen. This second stage generally takes not more than four to six hours for full development. A few hours after the second stage has become clear, the cells assume the form of moniliform threads. After this they assume the form of ordinary mycelium, with sparsely diffused cells. When the proportion of sewage is large, it is often accompanied by a distinct smell of butyric acid.A few experiments on mixtures of small proportions of sewage matter with water will give sufficimt data t o enable this peculiar fungus to be readily recognised. A pocket lens may sometimes be used with advantage. I n the second stage the form resembles a bunch of grapes. Finally the cells disappear and leave only ordinary mycelium. The following is the form in which the analysis should be reported :- Grains per gallon. Description of sample. Drawn. Temperature when drawn. Appearance in two foot tube. Smell when heated to 100° F. Chlorine in Chlorides. Phosphoric Acid in Phosphates. Nitrogen in Nitrates. Ammonia. Alburuinoid Ammonia. Oxjgen absorbed in 15 minutes at SOo F. Hardness before boiling (Clark's scale), Total solid matter dried at 212O F. Microscopical examination of deposit. Remarks. 9 9 5 9 4 hours 9 , ), after ,, 9 9THE ANALYST. 139 INSTRUCTIONS FOR WATER ANALYSIS. Substance determined. Chloride ................ Nitric Acid, Crum’s Procesr ,, ,, Copper Zinc.. ,, ,, or Aluminum , ................. 9, 9 , $ 9 1 9 9, t, 9 % 1 9 ,I 9 , Y 3 9, t Free and Albuminoid Ammonia.. .... Oxygen absorbed ........ 9 , ’ , . ....... 9 9 .......... 9 9 , . . . . . . . . . , , ........ 3, , Y , , ........ Total Solids ............ ,, ,, ............ FACTORS FACILITATING CALCULATIONS. Water taken. 100 C.C. 1400 grains. 250 C.C. 3500 grains. 100 G.C. 50 C.C. 1-40th gall. 1-70th gall. 500 0.0. 7000 grains. 250 C.C. 250 C.C. 250 C.C. 3500 grains. 3500 grains. 3500 grains. 3500 grains. 250 C.C. Volume or Weight obtained, Silver Sol. G.C. Silver Sol. grains, N,O, C.C. N,O, c.c, NH, grammes. NH, grammes. NH, grains. NH, grains. NH, C1. Sol. C.C. NH, C1. Sol. grains. 10 C.C. Permsng. used 15 C.C. Permang. used 20 C.C. Permang. used 100 grains used. 150 grains used. 200 grains used. Grammes. Grains. Faator to get grs. per gall. 0.7 =Chlorine. 0.05 E Chlorine. 0-175 Nitrogen. 0,193 Nitrogen, 576.45 Nitrogen, 1152.9 Nitrogen. 32.94 Nitrogen, 57-64 Nitrogen. 0.0014 NH, 0.0001 NH, 0.28 (1-:-). 028 (15-z). 0-28 ( 2 - z ) . 0 2 (1*5-:). 280 Total solids. 20 Total solids. 0.2 (1-Z). 0 2 ( 2 - 3 )ecimal plsce DWhiOhreBult 1 be reported. Second. Second. Fourth. Third. First. * A = C.C. or Grains of Hyposulphite solution corresponding to 10 c.c or 100 grains Permanganate. B = 9, 91 I , $ 9 ,, used after 15 minutes or 4 hours action. INSTRUCTIONS TO BrNDER.-Bind this opposite page 138.

ISSN:0003-2654    

DOI:10.1039/AN8810600128

出版商:RSC    

年代:1881

数据来源: RSC