@Hemical Section of the Franklin Institute
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June, I89I.] C/zemical Section. 46r PROCEEDINGS OF THE @HEMICAL SECTION OF THE FRANKLIN INSTITUTE. [Z*oceedz'Te~s of the staled meefinK, held Tuesday, May zg, x89L] HALL OF THE FRANKLIN INSTITUTE, PHILADELPHIA, May I% 1891. Dr. WM. H. GREENE, Vice-President, in the chair. Sixteen members and seven visitors were present. Dr. W. P. Mason, of the Rensselaer Polytechnic Institute. of Troy, N. Y., read a paper on, " Drinking Water and Disease." It was referred for publication. A discussion of the paper, which was.of much interest, followed, and was conducted by the author and Messrs. Pemberton, Jayne and Haines. Mr. Pemberton called attention to the conditions of the water supply of Chester and discussed the effect of Philadelphia sewage upon it. Dr. Bruno Terne presented a paper on "Meat Preservatives," giving a discussion of the ingredients and their effects upon the human system when present in meat used as food. The paper was discussed by the author and Mr. Haines. Adjourned. WM. C. DAY, Secretary. ON THE AMMONIA PROCESS OF WATER ANALYSIS. BY REUBEN HAINES. [Read al g/te staled meetinK, keld Aflril 2I, I39L ] Two forms of this process are in use, 6ne dealing with a half litre or a full litre of the water: the other requiring only ioo cc. for the distillation. The writer prefers the former, although some chemists find the latter fully as accurate and more convenient. The following notes indicate the practice of the writer for a number of years, in addition to the instructions given by Wanklyn. The amount of sample used is one-half litre, or, in some very impure waters, a less quantity of the sample diluted to half a litre with pure distilled water. 462 C-/ze~Jzic<~l, &'c~zoJz. [ J. F. I., The retort is of large size, having a capacity of from one-third to one-half gallon when completely filled, and is supported at the neck by a large retort-clamp upon a heavy iron stand. It should not be supported oi1 a ring, unless wire gauze be interposed, as otherwise there is great danger of fracture of the retort. If a Bunsen burner with wire gauze is used close up beneath the retort with such a body of liquid there is still danger of fracture. The neck of the retort is inclined ztpw(~rd at an angle of about 25 ° and attached to a Liebig condenser having an inner tube of one inch diameter, by a short piece of wide rubber-tubing in such manner that the ends of the retort and condenser are in close contact and that as little rubber as possible is exposed to the action of the hot vapor. In lieu of this arrangement a few inches of the end of the retort-neck may be bent downward parallel with the con- denser, and be made to enter loosely within the glass con- denser tube; a short piece of rubber-tubing overlapping the connection. In either ease, the rubber should be tied down to prevent leakage, but in such manner that the retort may readily be disconnected at the conclusion of the analysis. The rubber will have to be renewed after a time. The mode of connection recommended by ~Vanklyn has been shown by Dr. Smart, Mallet and others, to permit loss of ammonia by leakage. A rather rapid current of water should be maintained in the Liebig condenser. If this condenser alone is used, the current should be so rapid that the temperature of the water at the exit is not materially raised by the opera- tion if the water used has an original temperature of from 5o ° to 6o ° P. If the water is of higher temperature than this ice should be used for cooling it. A better plan is that adopted by the writer, which consists in attaching the lower end of the Liebig condenser as closely as possible to a glass vertical coil condenser of the Mohr pattern, of which the outer vessel is an inverted jar receiver (a large inverted bottle with the bottom cut off will do very well), into which broken ice may be placed, espeeialiy irt hot weather. The glass tube forming the coil has an inside June, ,89r. ] C/zcmical Section. 46~ diameter of about half an inch. Beneath this second con- denser a short nearly horizontal tube, conducts the distillate to the Nessler glass out of reach of contaminating dust, etc., that might chance to fat1 from the vertical condenser. By having the retort sufficiently large, and by inclining its neck upward all danger of the permanganate being thrown over into the condenser is avoided. Risk of fracture is greatly lessened by the use of the retort damp, and by the rod of the stand acting as a sort of spring to moderate the shock of bumping, and the retort may thus last in frequent use for a very long time. One of mine lasted several years, but it became unavoidably weakened in time by the corro- sive action of the boiling alkaline liquid. By the above- described arrangement of the condensing apparatus, the distillate may be obtained ata given uniform temperature in all analyses in order to get uniform depths of color in the Nessler testing, a precaution to which some one has called attention. The risk of loss by imperfect condensa- tion of ammonia during regular distillation, or through the ontrush of gusts of vapor produced by turbulent boiling is also avoided. The condensing tube should, on account of this latter circumstance, be of comparatively large diameter throughout its whole length. With the above arrangement I have not found any loss by imperfect con- densation, if the temperature of the distillates did not exceed 6o ° P. If a lower temperature than this is adopted, the distillates should be allowed to stand unti~ they acquire a uniform temperature before applying the Nessler test. The arrangement I have adopted was suggested by reading tlle ]e~ort otz Water A1zalysis, by Prof. Mallet, to the National Board of Health, I88z, in which this loss of ammonia occurring when Wanklyn's instructions are fol- lowed is referred to, and a somewhat different arrangement suggested for avoiding it. In experiments with a known solution of ammonium chloride this loss was found by Dr. Smart to amount to an average of about seven per cent. of the whole amount that should have been obtained. It should, however, be noted that Mallet states that "the tem- perature of the condensing water varied from 25 ° to 25°'5 C.!' 464 C/eem£a/ ~S'eclioTz. [ J. F. I., which is a rather high temperature. In these experiments the current of water in the condenser was so rapid that its temperature was not sensibly raised by the process, even when fifty ce. of distillate were obtained in eight minutes. The distillates of fifty ec. each are received directly into tile Nessler tubes marked at fifty ec., and tile earlier portions may be Nesslerized while the distillation is progressing. Wanklyn advises to Nesslerize only the first distillate of fifty co. free NIt a and add to this one-third. In waters containing enormous amounts of free ammonia, however, it is better either to distil the whole of the free ammonia into a flask in one portion, dilute, and take an aliquot part for the Nessler test, or to follow Dr. Smart's plan of Nesslerizing each successive distillate of fifty" cc., previously diluting if necessary. Dr. Smart t)elieves that the presence of u]:ea in the water may be detected by peculiarities ill the manner in which the free ammonia distils over in the successive portions. I have found that polluted waters containing enormous amounts of free ammonia such as to give a very deep color or a precipitate by the Nessler test in fifty" ec. of the original sample appear to yield four-fifths or five- sixths of the whole amount in the first portion of rift)" co. instead of three-fourths, as stated by \Vanklyn. It is not advisable to put anything whatever, such as pieces of ignited pumice, tobacco pipe, etc., inside the retort to moderate the bumping, as suggested by some, there being too much danger of introducing thereby organic or ammoniacal impurity. The bumping can be controlled if necessary by lowering the flame and by tapping gently on the retort so as to produce a concentric wavy motion on the surface of the liquid, which will cause the steam to rise more regularly and in smaller bubbles. A Bunsen burner, giving a large flame, should be used. I prefer one having several jets, or a rose-burner, and place it quite close to the retort, without any intervening wire gauze. All the apparatus used for water analysis should be set aside exclusively for this purpose. Thorough washing of each article immediately before use is very essential. To be thought "dean enough " is by no means sufficient. The June, I891.] Chemical Section. 465 whole condensing apparatus set up ready for use, but dis~ connected from the retort, can be satisfactorily washed by flushing it thoroughly two or three times with clean hydrant water, closing the outlet by the finger or a dean cork until the condenser tube is full and then allowing the water to run out. This method of washing is much better than distilling some clean water through it as advised by some. The retort should be rinsed with a little concentrated sulphurie acid and washed thoroughly with dean tap water, and then immediately connected with the condenser. The above form of apparatus may be considered by some to be cumbrous and to occupy too much space, yet I think it possesses certain real advantages whieh offset these objec- tions.