33ºC A QUANTOS GRAUS FERVE UM MAÇÃO ESTUDO CRÍTICO E ANÁLISE DAS CINZAS DA COMBUSTÃO UM LIVRO EM QUATRO CANTOS E DOZE PÉNALTIES ....ORGANIC MATTER FREE AND ALBUMINOID AMMONIA The determinatioiis of solids and of chlorine, described in the preceding chapters, are only of secondary importance in com- parison with determinations of organic matter in drinking- water; and it is to the latter that the water-analyst should chiefly direct his attention. The earliest method of estimating the organic matter was by the loss on ignition. The solid residue got on evaporat- ing a given volume of water to dryness was carefully dried, weighed, ignited, and again weighed; and the difference in weight before and after ignition was taken to represent organic matter. To this procedure there are very many objections. The loss on ignition, besides including the amount of organic matter dissipated or burnt during the ignition, included much else. There was loss of carbonic acid from the carbonate of lime, and loss of water when a hydrated salt, such as sul- phate of lime, became an anhydrous salt, and there was loss of acid from magnesian salts if they happened to be present in the solid residue. An attempt was made to get over these difficulties by the employment of a small and known weight of carbonate of soda, which was put into the water before evaporation to dryness, and the weight of which was after- wards subtracted from the weight of the water-residue. The loss of carbonic acid from the carbonate of lime was repaired, by careful treatment, with, solution of carbonic acid and redrying at 130° C. By these devices, as tbose can testify who have worked the process, it was quite possible to get very constant results ; but having got the results, new difficulties started up, and it was shown that there still re- mained the loss in weight, occasioned by the destruction and dissipation of the nitric acid which exists in considerable quantities in most drinking-waters. When a water-residue is ignited, it loses nitric acid, and gains the equivalent of car- bonic acid ; and the loss in weight involved by this exchange is far larger than the organic matter. In consequence of the adoption of the ignition-process for the estimation of the amount of organic matter in water, a very exaggerated estimate of quantity of organic matter actually present in waters used to prevail among chemists. Thus the organic matter, as determined by this process in the water supplied by the Thames Companies to London, was from 15* to 17* parts per million (or a httle over one grain per gallon). The water of the Kent Company, which is now known to be all but absolutely devoid of organic matter, showed, in like manner, a loss on ignition amounting to 16*5 parts per million. In truth, however, these numbers do not so much represent organic matter, as exchange of nitric acid for its equivalent of carbonic acid ; and chemists have been agreed for some years in rejecting the ignition-process in the estimation of the organic matter in drinking-water. The next process which was tried was the permanganate- process. A dilute solution of permanganate of potash, of ascertained strength, was prepared. To a given volume of the water to be tested, this standard solution of permanganate was added as long as it was decolorised b^ the water. From 30 WATER- ANALYSIS. the quantity of permanganate destroyed, the quantity of oxygen taken up by the water could be calculated, and waters could be compared together as to their deoxidising powers. This process was a great advance on the ignition- process, but still it did not prove to be satisfactory, and has been to a great extent abandoned. One of its striking advantages over the combustion-process was that the pre- liminary evaporation to complete dryness (which risks loss and destruction of organic matter) was altogether avoided. The defects of the permanganate-process are its want of delicacy, and also the circumstance that albumen is not readily attacked by the standard solution of the permanganate. The next process which we shall mention is very unsa- tisfactory in every way. Instead of estimating the organic matter by loss on ignition, an attempt was made to perform an organic analysis of the dry water-residue, and to determine the carbonic acid and nitrogen resulting from its combustion with excess of oxide of copper and chromate of lead. This method was proposed by Dr. Frankland, and brought out by Drs. Frankland and Armstrong in the year 1868, and an account of it may be found in the Journal of the Chemical Society for that year. To a great extent it was a going back to the errors of the earliest method. There was the risk of destroying the organic matter during the evaporation to dryness in the water-bath. The nitric acid, which was one of the great sources of difficulty in the ignition-process, remained a source of difficulty in Frankland and Armstrong's process. As may be seen, on referring to the account of the process in the Journal of the Chemical Society, Frankland and Armstrong sought to destroy the nitrates by means of sulphurous acid applied to the water during its evaporation ORGANIC MATTER. 3 1 to dryness. It is true that the nitric acid may be utterly destroyed in that manner, but it is only too plain that that cannot be done without destruction of the organic matter; so that the analyst who should attempt to work the Frank- land and Armstrong process is placed in the dilemma of either leaving nitrates in the water-residue, or else of destroy- ing the organic matter before making the combustion. The circumstance that the amount of nitric acid far ex- ceeds the organic matter, imparts special importance to this difficulty. Another fatal difficulty of the process depended upon the minuteness of the organic matter in drinking - water. The quantity of organic matter in a litre of water (and that is the quantity which Frankland and Armstrong evaporated to dryness to yield the water-residue for one analysis) is too little to admit of an organic analysis. Frankland and Arm- strong have pubhshed some determinations of organic matter in a litre of water, and exhibit a greater experimental error than the total quantities which occur in water of average goodness. In short, the process is thoroughly untrustworthy, and being also very difficult and costly, has not met with general acceptance. The methods of determining the organic matter which we have just described are methods of the past, and have only an historical interest. We next pass on to the method which is now in general use among chemists, and which is known as the ammonia-process, giving, as characteristic data, the "Free ammonia" and "Albuminoid ammonia" yielded by waters. This method dates back to the year 1867, when it was ^2 WATER-ANALYSIS. brougM out by Smitli and onrselves in a paper read before the Cbemical Society on the 20th of June in that year. In its earliest form it was described in that paper, which was published later, in the year 1867, in the Journal of the Chemical Society. As originally described, there were two distinct modifications of the process, and at the time of the publication of that paper the precise distinctions between the two modifications were little understood. Later in the year 1867 a second paper bearing on the subject was read ; and in the spring of 1868, further researches bearing on the subject were pubhshed by us in the Journal of the Chemical Society, and the first edition of this treatise was published. Except the ammonia-process, there never was a new method of analysis which, within a week or two of its discovery, at once assumed its definite form — a form to which many thousands of analyses brought no essential modification. On the 20th of June 1867, two varieties of the water-process were described, and preference was given to one of them ; and to-day, after many thousands of these analyses have been made by many chemists In my own laboratory the Nessler glasses are cylinders, 17 centimeters in height and 4 centimeters in diameter. They are marked with a file-mark at 50 c. c. capacity. Erom half a dozen to a dozen are necessary. I use also a white porcelain tile for them to stand upon when they are used. (10) A half -litre flash to measure out the sample of water is required. It should never be used for organic fluids, and indeed it is best to keep it exclusively for water. (11) Tlie measure for solution of Potash and Permanganate of Potash is a convenient glass, with a simple mark at 50 c. c. capacity. To pour well is an essential qualification that such a glass should possess. I am in the habit of using a thick glass-vessel, which is an apothecary's dispensing four-ounce measure, and which I bought in an ungraduated state. {12) A Graduated Burette, divided accurately into cubic centimeters, and provided with a glass stopcock, is used for measiiring out the dilute standard ammonia. It is held by any convenient holder. The Pipette for Nessler Reagent is made of a piece of glass tube, and requires just one file-mark at the 2 c. c capacity. (14) Bottles are required to liold tlie dififerent solutions. It is of importance that the bottle holding the solution of potash and permanganate of potash should pour well. A large glass funnel is also required. The coNVenience of having a water-supply and sink close at hand will be readily appreciated. It will also be found to be advantageous to keep a table, or part of a table, appropriated exclusively to water-analysis, and to appropriate a set of apparatus to it. Thus the funnel, the half-litre flask, the retort and condenser, burette, pipette, and Nessler glasses, should not be used for anything else but water-analysis. One very important matter in testing of this order of deLIcacy is the cleaning and washing out of the apparatus ; and it should be borne in mind that all glass surfaces which have been exposed to the air for any length of time are liable to contract traces of ammonia from the air ; and the rule which has to be observed, in order to ensure accuracy, is to wash out with clean water immediately before use. Turthermore, it may be remarked that for these washings it is unnecessary to employ distilled water; and that the ordinary town water is, as a rule, everything that can be desired for the purpose. There should, however, be no stint of the quantity of water. The analysis is performed in the following manner : — The retort having been washed out with a little strong acid (either hydrochloric or sulphuric acid), is then washed out with good tap water, until the few drops which drain out do not taste acid. It is then mounted in its holder, and properly connected with the Liebig's condenser, either by means of a wide india-rubber tube, or else it is jUst packed into the condenser by means of a little writing-paper. Half a litre of the sample of water is next measured in the half-litre flask, and poured into the retort through a large funnel kept specially for the purpose. Then the stopper or cork, which must be kept scrupulously clean, is put into its place in the retort, and the Bunsen lamp is lighted, and the flame applied externally to the naked retort. The retort must be thrust right down into the flame, which, however, must not play upon the surface of the retort higher than the level of the liquid within the retort. In a few minutes the contents of the retort will begin to boil, and the water will begin to distil over. The distillate is to be collected in the glass cylinders for the Nessler test. When 50 c. c. of distillate have distilled over, the cylinder is to be changed. The first 50 c. c. should then be Nesslerised, which will be explained further on. The distillation is to be continued until 150 c. c. have come over, and the 150 c. c. of distillate are to be thrown away. Having done so, and thereby reduced the contents of the retort from 500 c. c. (the quantity originally taken) to 300 c, c, the distillation is stopped for a moment. Fifty cubic centimeters of the solution of potash and permanganate of potash, which has been described, is then to be poured into the retort through a wide funnel, and the distillation proceeded with. At this stage of the operation it is sometimes necessary to shake the retort gently, in order to avoid bumping. This is especially the case in the analysis of very bad water. With a little practice, and a little presence of mind, the operator will OR NOT very easily overcome difficulties of this description. The distillation must be continued until 50 c. c. of distillate have come over, and this must he collected in a cylinder for Ness- lerising. A second 50 c. c. must be collected in another IsTessler cylinder, and a third 50 c. c. must be collected; and that having been done the distillation may be stopped, and the apparatus left standing until it is required for another analysis. Nesslerising, which has been mentioned in the above pas- sage, is the operation of finding the strength of dilute solutions of ammonia by help of the Nessler test — a test discovered by a chemist named Nessler. The preparation of the !N"essler reagent has already been described in detail. Let it be re- quired to tell how much ammonia is present in 50 c. c. of distillate contained in one of the cylinders above mentioned. For this purpose 2 c. c. of Kessler reagent are dropped into the 50 c. c. of distillate. This is best done by aid of the appropriate 2 c. c. pipette above mentioned. The pipette also serves as a convenient stirrer, to stir up the liquid after the addition of the JSTessler reagent to it. If the 50 c. c. of distillate contain any ammonia, it will soon after the addition of the Nessler reagent, as just described, assume a rich brown colour; and the more the ammonia, the deeper the colour. The next step is to imitate the depth of colour given by the distillate. In order to do so, a clean cylinder is taken, and into it is dropped a certain measured volume of the standard solution of weak ammonia, which is filled up with distilled water to the 50 c. c. mark on the cylinder. Two cub. cent, of Kessler reagent is then dropped into it by means of the pipette, and the whole is very thoroughly stirred up. ORGANIC MATTER. 4 1 The 50 c. c. of distillate in its appropriate cylinder, and tlie 50 c, c. of water containing the standard ammonia, are then placed side by side on a white surface (a white porcelain tile answers very well), and carefully looked through, and a judgment is arrived at as to which is of the deeper colour. If they be of equal depth, the IsTesslerising is accomplished, inasmuch as the quantity of ammonia required to imitate the colour, which Nessler reagent imparts to the distillate, is the quantity of ammonia in the distillate. If the two solutions be not of equal depth, another standard must be made up with water, dilute standard ammonia, and Messier reagent, and another comparison must be made. With a little practice Nesslerising becomes very easy. In the course of a water-analysis it will be perceived that ammonia is to be looked for at two stages : firstly, before the addition of the potash and permanganate ; and secondly, after the addition of the potash and permanganate. The ammonia which comes over in the first stage is the " free ammonia," and that which comes over in the second stage is the " albuminoid ammonia." The recommendation has been given to Nesslerise only the first 50 c. c. of free ammonia, and to throw away the next 150 c. c. Formerly it was our custom all four 50 c. c. of free ammonia; but that was a useless trouble, in asmuch as the first 50 c. c. invariably contains three-quarters of the total amount of free ammonia. The rule is, therefore, to iJ^esslerise the first 50 c. c. of free ammonia, and then to add one-third. Thus, if in the first 50 c. c. of distillate the quantity of ammonia were found to be 0.02 milligramme, the total free ammonia would be 0.027 milligramme. In the instance of the albuminoid ammonia, it is necessary to Nesslerise each separate 50 c. c, of distillate, and to add . the amounts together, in order to arrive at the total albuminoid ammonia. Since a litre of water is taken for the analysis, the results must be multiplied by two, in order to make them count upon the litre ; and if that be done, we shall then have the " free ammonia " and " albuminoid ammonia " expressed in milligrammes per litre, or in parts per million (which is the same thing). The following example of the maimer in which the notes of a water-analysis are kept in the laboratory may be useful. Half a litre of water was taken for analysis. Free ammonia (Correction) Albuminoid ammonia .01 milligrammes Date. Ammonia. 1867. Free. Albuminoid. July West Middlesex Water Co. AS COUSAS MUDAM POUCO NESTE MUNDO E NO OUTRO AINDA MUDAM MENOS...Eive springs in the West of England. July 1868. No. I, containing 26 gr. solids per galLON PURE SHIT ...A PRACTICAL TREATISE ON THE EXAMINATION OF POTABLE WATER, BY ALFRED WANKLY M.R.C.S. CORRESPONDING MEMBER OF THE ROYAL BAVARIAN ACADEMY OF SCIENCES HONORARY MEMBER OF THE UNIVERSITY OF EDINBURGH PUBLIC ANALYST FOR BUCKINGHAM, HIGH WYCOMBE, AND SHREWSBURY

2014 m. spalis 20 d., pirmadienis

Such, then, is the raw material with which the Thames 
coinpanies have to work ; such is the condition of the water 
of the Thames before purification by the companies. 

We have, likewise, made repeated analyses of the water 
with which the JSTew Eiver Company serves the inhabitants 
of London. 

Our results are as follows : — 



ORGANIC MATTER.

 The retort employed for the ammonia-process may he used, 
and having been cleaned and mounted as if for the ammonia- 
process, is charged with one litre of the water to be examined. 
Before beginning to distil, 5 c. c. of the solution of caustic 
potash is dropped into the water contained by the retort, and 
then 5 c. c. of the solution of permanganate are very care- 
fully measured, and likewise dropped into the retort, which 
is then heated and its contents rapidly distilled until about 
900 c. c. have distilled over. That having been done, the 
heating is stopped, and the observation is made that the liquid 
remaining in the retort retains a pink colour. Then 10 c. c. 
of the solution of sulphuric acid are dropped into the retort 
and shaken up with the contents of the retort. Then 5 c. c. 
of the iron-solution are to be dropped into the retort, and in 
a few minutes the liquid will become quite colourless. That 
having been attained, the solution of permanganate of potash 
contained in the graduated pipette is carefully dropped into 
the liquid, and the point is accurately noted at which the 
red colour just begins to be permanent. 

The following data will thereby be obtained : — 

(a) Total number of c. c. of permanganate used up. 

(&) Total number of c. c. of permanganate used up by the 
iron-solution. 

The difference between these figures is the number of c. c. 
of permanganate consumed by the organic matter in one 
litre ot water, or the number of milligrammes of active oxygen 
consumed by the organic matter in one litre of the water. 
An example will render this description intelligible. 

 One litre of the water supplied by the South wark and 
Vauxhall Water Company was placed in the retort, and 5 
c. c. of the potash-solution and 5 c. c. of the permanganate- 
solution were added. The distillation was then continued 
till only a small bulk of liquid (100 c. c.) remained in the 
retort ; 10 c. c. of the sulphuric acid was then added, and 
5 c. c. of iron-solution, which rendered the liquid quite 
colourless. Then the permanganate-solution was run in until 
a red colour just formed and did not vanish on shaking up : 
3.7 c. c. being required for this purpose. 

"We have, therefore : — 

c. c. 

Total permanganate used . . . . 8.7 
Permanganate used by the 5 c. c. of iron- 
solution ...... 5.0 

Permanganate consumed by the organic 

matter in the litre of water. . . 3.7 

Or, one litre of this sample of Southwark and Yauxhall water 
consumes 3.70 milligrammes of oxygen. 

In analysing very bad waters it will be found that in the 
course of the distillation the 5 c. c. of permanganate-solution 
is exhausted. When this happens, another 5 c. c. of perman- 
ganate must be dropped into the retort, and the operation 
continued, care being taken to leave an excess of perman- 
ganate before the stage is reached at which sulphuric acid is 
added. 

This is the place to call attention to a peculiarity of the 
action of permanganate-solution on iron-salts which has, I 
believe, occasioned the belief that there is a want of precision 
in the action. If the standard solution of permanganate be 
added to an acid solution containing proto-salt of iron, a point 
wiU soon be reached at which the faint pink colour ceases to 



THE MOIST COMBUSTION-PROCESS. 57 

disappear on shaking np the solution, but after the lapse 
of a few minutes the pink colour gives place to a brownish 
precipitate. Probably this last destruction of permanganate 
is due to the formation of Ferric acid : but it takes place only 
after lapse of time, and the only consequence which results 
is that, in titrating iron-solutions with permanganate, the 
final reactings must be immediate, and not after lapse of 
time. 

The moist combustion-process, as above described, will 
be found to involve no practical difficulties. It may be 
carried out either on a smaller or a larger scale, suitable 
modifications being made to meet the requirements of the 
case. 

The following examples will serve to give some idea of the 
results obtainable on submitting different kinds of drinking- 
water to the process. 

Waters of acknowledged purity have given the following 
numbers : — 

Oxygen consumed. 
Parts per million. 

Csneiullj redistilled \Y8ite,T . . , . 0.14 

Distilled water . '. . . . . 0.32 

Filtered waters (through Silicated carbon filter) 0.48 

Kent Water Company . . . . . 0.48 

Well in Croydon . . . . . . 0.40 

Waters of average purity have given : — 

Oxygen consumed. 
Parts per million. 

1878. June 15.  Eiver Company . . 2.48 
May 17. Chelsea Company . . .2.28 

DEPOIS DE LER A CIDADE E AS SERRAS NUNCA ME APETECEU IR A LADO NENHUM SEI LÁ JÁ TER DE LER AS CIDADES E AS SERRAS JÁ ERA UM TRABALHÃO E INDA POR CIMA FICAR COM VONTADES DE VIAJAR P'LA PARVÓNIA ?

ISTO ENTRE LEITORES E E-LEITORES HÁ GENTE PARA TUDO

MADRUGADA DE 11 DO 12 DE 1991 ESTRADAS GELADAS UNS GRAUS APENAS

ABAIXO DO ZERO E 270º ACIMA DO ZERO DITO ABSOLUTO

QUAL O PROBLEMA DO MIKAIL JACK SON QUESTIONA UMA FOLHA DE JORNAL

COMO O SUN OU COISA E TAL

QUER MUDAR DE COR

COMO MILHÕES DE INGLESES QUE VÃO PARA ESPANHA E ALGARVE E GRÉCIA

FICAREM COR DE LAGOSTA E NINGUÉM ACHA MAL NENHUM NISSO

A NICE BRONZEADO OU A FUTURE SKIN CANCER É UM DESPORTO MUNDIAL

SE NINGUÉM SE IMPORTA COM QUEM QUER MUDAR DE SEXO

PORQUE HAVERIAM DE QUERER COMPRAR ESTES JORNAIS ...

ANÁLISE DA ÁGUA MINERAL

VALORES ACIMA DE 1,5 MG'S OF FLUORIDES PER LITRO ORA PER PINT

É .......TABELA DE CON VERSÃO

NÍVEIS DESTES PODEM PROVOCAR DESCOLORAÇÃO DOS DENTES

DAÍ É SÓ OLHAR-ME AO ESPELHO PRA COMPROVAR


E PRONTO QUE PODERIA POR NO RELATÓRIO

A MAIORIA DAS ÁGUAS MINERAIS SÃO UM MITO

E A MAIOR PARTE DESTES MINERAIS SÃO DESNECESSÁRIOS OU MESMO

PERIGOSOS ....CHUMBO ALUMÍNIO ARSÉNICO BOM ARSENITOS DÁ NA MESMA

A ÁGUA É BOM SOLVENTE

EVIAN ....NITRATOS NITRITOS PESTICIDAS

E PAGAM UM BALÚRDIO POR ÁGUAS DESTAS NOS STATES

VANTAGENS DUM BOM MARKETING NUS ANUS 80...

ORGANIC COMPOUNDS 120 MILIGRAMAS

E SENDO DISPENDIOSAS AS ANÁLISES PARA AS DESPISTAR

NUNCA SE FAZ

BENZENE ...127 PPB IN EAU PERRIER ,,,,,,,,,,,,,,,

CONTAMINANTES NA LAVAGEM DAS GARRAFAS ...DETERGENTES

DÃO BOM NÍVEL DE FOSFATOS

GARRAFAS SEM RETORNO OU TARA SÃO O FUTURO

DEIXA DE SE LAVAR E O VIDRO É SEMPRE NOVO...

2 MICROGRAMAS DE URÂNIO ÁGUA DE MACIÇOS GRANÍTICOS OU AFINS

7 MICROGRAMAS DE THALIUM PRA FAZER CAIR O CABELAME