T H E JOL-RA\-AL OF I S D L - S T R I A L A-YD E - Y G I X E E R I S G C H E M I S T R Y
474
of sulfur present) are sufficient. To give a n idea of the results to be had b y the other three methods, Table IV has been included. These data show the results which were obtained under conditions distinctly unfavorable for accurate results, only 6 to 30 mg. of sulfur and large and varying amounts of ammonium carbonate being present in the samples used. These conditions were chosen as representing those with which we had t o deal in the gas testing; and if in other work larger amounts of sulfur were present or greater care was exercised no doubt much more exact results could be had. For gas testing the accuracy here shown is ample, since i t is greater than the accuracy obtainable in the condensation of the sulfate.
Vol. 5 No. 6
fuels can be classified in four groups, the general principles o f which are as follows: ( I ) The gas is burned and the sulfur oxides in the products of combustion are condensed or absorbed, oxidized to sulfate, and determined as such. ( 2 ) The sulfur compounds are oxidized by liquid reagents giving the sulfate, which can be determined directly. (3) The sulfur compounds are oxidized by burning the gas but the sulfur is absorbed and determined as sulfur dioxide. (4) The sulfur compounds are reduced to give hydrogen sulfide, which is then absorbed and determined. TABLE IV-COMPARISON OF METHODS FOR SULFATEDETERMINATION. The methods of Group I have been most used in SULFUR(MG.PER G . OF SOLUTION) IN STANDARD HzS04 SOLUTJON American practice and are generally considered the DETERMINED B Y DIFFERENT METHODS IN PRESENCE OF EXCESSOF .4MMONIUM CARBONATE EXCEPT AS most accurate and convenient, either for works conOTHERWISE NOTED trol or official testing. Tests have been made on five Method 3. Volumetric forms of apparatus of this group and one or more Volumetric ___7 against Oxalate standforms of each of the other classes; but the principal h*aOH and Method 1 Method 2 ard (no carHzE04 investigation was limited to the three forms, all of benzoic acid Gravimetric Gravimetric bonate added) standard group one, which appeared t o be most satisfactory for 1.589 1.591 1.597 1.602 1.595 93 91 93 1.597 1 ,602 general use. These are known, respectively as the 90 90 92 1.600 1.597 Referees apparatus, the Hinman-Jenkins apparatus, 92 1.609(a) 99 1.599 1.601 and the Elliott apparatus. 92 1.596 97 1.602 1.596 ... 1.589 92 96 92 The Referees apparatus is too well known to re... 1.574 89 88 99 quire a detailed description here. I t consists of a ... 1.575 90 92 91 .. 94 1,600 ... ... Bunsen burner surrounded b y pieces of crystallized __ __ __ ammonium carbonate, from which the products of Av. 1.591 1.592 1.595 1 ,600 1.589 combustion of the gas, mingled with vaporized am( a ) Omitted from average. monium carbonate, pass into a condensing cylinder The first set of results in Table IV by Method 3 are where the sulfur oxides are absorbed in the water calculated on the basis of the value of the thiosulfate solution obtained b y titration against a permanganate condensed from the products of combustion and are solution, whose value was obtained against sodium oxidized, in the presence of the ammonia, to amoxalate. I n the second series the thiosulfate was monium sulfate. The Elliott apparatus is essentially a large Referees standardized against the sulfuric acid value given in apparatus, the principal difference being the use of the first column of the table. For accurate work the gravimetric methods, with the two condensing cylinders through which the gases precautions which have been carefully developed by successively pass. The Hinman-Jenkins apparatus' many experimenters, are to be preferred; but for differs from the Referees greatly in form, but in rapid work the turbidimetric and volumetric methods principle only in the use of concentrated ammonium are very useful. They can be applied in many lines hydroxide instead of ammonium carbonate as a of work other than gas testing, since in each the value source of ammonia. of the standard is fixed against similar material whose To compare the several forms of apparatus, two or value has been previously established by other methods.' more were operated a t the same time, being supplied If the calibration and testing procedures are identical with gas from a common source. Suitable prethe variation of individual testsfrom the average or cautions t o maintain a uniform supply to each apcorrect value is the important factor; this variation paratus and t o prevent errors due t o sulfur in the air has been shown by our experience t o be about one of the room were taken. The meters used were freper cent or less in the volumetric and five per cent or quently compared to determine their relative accuracy. less in the turbidimetric method. One series of comparisons made upon the three BUREAUO F STANDARDS apparatus to determine the best conditions of operaWASHINGTON tion and sources of error is summarized in Table I. _____~______ THE DETERMINATION OF SULFUR IN ILLUMINATING GAS' The results tabulated include only those obtained under normal working conditions, and not those obtained B y R. S. MCBRIDEAND E. R. WEAVER *when variations were made which would be avoided The methods for determination of sulfur in gaseous in practice. The sulfate in the condensed liquids was 1 Paper presented at the Annual Meeting of the American Chemical determined as barium sulfate by a method closely Society, Milwaukee, March, 1913. Published by permission of the Director of the Bureau of Standards. This paper is a report on tests made at this resembling t h a t of Johnston and Adams,' the weight ~
-
~
Bureau, preparatory to the recommendation of a method for official inspection of gas; a more complete report on this same investigation is to appear soon i n Technologic Paper No. 20 of the Bureau.
1
J. Ant. Chem. Soc , 28,
2
Ibtd., 33. 829-45 (1911).
543 (1906).
June,
I913
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R i N G CHEililISTRY
of the precipitate being corrected for silica dissolved from the glass by the alkaline liquids. The cause of the lower results obtained by the use TABLEI-FINAL COMPARISON O F REFEREES,ELLIOTT AND HINMAN-JENKI N S A4PPARATUS
A. Gas burned a t the rate of: Jenkins 0.60 cu. ft. per hour.
Test No. 10 11 12 13 14 15 16 17
Referees 0.60, Elliott 0.96, Hinman-
ReferElliott: Ratio Ratio ees KO. 1: Sulfur Elliott: Hin.-Jenk.: Hin.-Jenk. Ratio Sulfur per per 100 Refer- Sulfur per ReferElliott 100 cu. f t . cu. ft. ees No. 1 100 cu. f t . ees No. 1 Hin.-Jenk. 11.3 13.8 13.9 13.4 13.4 13.5 13.8 13.6
10.9 14.3 14.8 13.9 12.6 14.5
98.2 103.6 106.6 104.1 93.8 109.9
.. .
...
Av.
...
...
...
100.0 106.0 103.3 104.7 103.7 101.0 101.5
103.7 100.8 101.3 90.0 106.0
102.9
100.3
102.7
B. Gas burned at the rate of: Jenkins 0.65 cu. f t . per hour. 18 19 20 21 22 23
15.2 13.9 14.3 15.4 13.1 13.2
14.9 14.0
..
98.0 101.0
... ...
13.1
100.0
..
,..
Av.
24 25 26 27 28 29
-
13.5 10.1 16 1 13.5 11.6 13.2
14.3 13.0 13.3 14.4 12.9 12.2
-
108.5 96.0 103.0
13.9 9.9
..
...
.. ..
...
-
...
102.5
OF
SULFURCONDENSED IN DIFFERENTPARTSOF
THE
ELLIOTT APPARATUSAT DIFFEREST RATESOF GAS CONSUMPTION Sulfur in Sulfur in Total 1st tower 2 n d tower sulfur (grains (grains (grains per Rate 100 cu. f t . per 1OOcu. per 1OOcu. f t . of gas) f t . of gas) (cu. f t . per hr.) of gas)
Referees burned Per cent a t 0.5 of total cu. f t . per hr. condensed (sulfur, in sec- grains 100 CU. ond tower ft. of gas)
1.36
5.7 8.2 4.9
3.7 4.7 1.5
9.4 12.9 6.4
39 36 23
15.5 14.2 11.5
1.20
13.9 9.4 14.8
1.1 0.5 1.8
15.0 9.9 16.6
8 6 8
13.8 10.3 16.1
11.5 10.4 10.7 12.1 12.2 13.1
1.7 3.9 2.5 1.6 2.0 2.1
13.2 14.3 13.2 13.7 14.2 15.2
1 3 2
13.7 12.8 12.4 13.6 13.8 15
.. ..
.. ..
0.9
.. .. .. .. ..
1 1 1
.o
..
94.0 93.6 93 . O 93,s 98.5 92.5
104.1 107.8
94.2
104.4
... ... 101.7
. .
Referees 0.50, Elliott 1.20, Hinman-
9.9 16.6
15.0
...
Referees 0.49, Elliott 1.20, Hinman-
99.7
Gas burned at the rate of. C. Jenkins 0.50 cu. ft. per hour.
Av.
.. 13.8 14.7 13.7 14.0 14.0 14.0 13.8
TABLE11-AMOUNT
475
100.7 96.0
107.9 100.0
..
...
...
13.9 12.1 13 .O
102.6 103.9 98.3
. .
100.3
103.9
. .
serious source of error in any apparatus of this type is a n insufficient or irregular ammonia supply. Table I11 shows the effect of using in the Referees apparatus lumps of carbonate which had previously been used and which were, therefore, incrusted with bicarbonate. As much ammonium carbonate was used in each case as would lie in the annular space about the burner. From the decrease in efficiency of condensation on long use of the carbonate, shown by the results in Table 111, it appears that a Io-hour run, using a single supply of carbonate, could hardly be expected t o give more than 90-95 per cent or a 2 0 hour run more than 75-80 per cent of the sulfur burned TABLE111-EFFECT OF USING OLD AMMONIUM CARBONATE ON REFEREES APPARATUS
...
of the Referees apparatus was next investigated. It was found that by the addition to the Referees apparatus of a second condenser, which practically doubled its condensing surface, the amount of sulfur found was increased by about I per cent. The effect of v a ~ ~ - : nthe . g rate at which the gas was burned, shown in Table I , is still better indicated in Table 11, which shows the percentage of sulfur condensed in each tower of the Elliott apparatus with the gas burning at three difierent rates. The significance of the results appears at once when we remember that the first tower with its connections is practically a large Referees apparatus and the sulfur which passes into the second tower is lost in the Referees form, From our experiments we believe that for each apparatus there is a certain rate of gas consumption above which the loss of sulfiir increases out of all proportion to the increased rate at which the gas is burned. If the ammonium carbonate or hydroxide is renewed as frequently as is recommended, one cubic foot per hour for the Elliott and one-half cubic foot per hour for the other forms of apparatus are safe rates; b u t t h e loss increases rapidly at higher rates. Indeer'.. the amount of sulfur condensed p r hour in the> Elliott apparatus was less when the pas was burning 1.36 cu. f t . per hour than when burning a t 1 . 2 0 cu. it. per hour. Our work throughmt indicated that the most
Previous use of carbonate Test No. (hours) 30 6 .O 31 32 33 34
6.0 6.5 6.0
Sulfur Sulfur con- condensed Length densed with with fresh of run old carbonate carbonate Ratio of (grains) A (grains) B A t o B (hours) 6.5 6.5 6.0 6.0
No carbonate used
7 .O 11.5 9.5 11.0 5.1
14.0 14.9 13.9 13.6 16.8
0.50 0.77 0.78 0.81 0.30
Table IV shows the effect of varying the ammonia supply to the Elliott apparatus upon the percentage of the total sulfur which escapes from the first tower and is collected in the second. Similarly, Table V shows the percentage of total sulfur collected in the added condenser of the Referees apparatus previously mentioned under Table I : first, when nothing was added to this second condenser; scco?id, when concentrated ammonium hydroxide was slowly dropped in a t the top of the second condenser; third, when a solution of hydrogen peroxide and ammonium hydroxide was added in the same way. The object. of adding hydrogen peroxide was to see what effect an oxidizing substance would have upon the absorption of the sulfur dioxide; from the results obtained this effect appears to be negligible. Another series of experiments showed that alkalinity of the atmosphere as distinguished from alkalinity of the condenser surface was necessary for proper condensation of the sulfur. SUMMARY
A comparison of the Referees, Hiqman-Jenkins, and
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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
Elliott apparatus for the determination of sulfur in gas showed that any of these apparatus is capable of giving satisfactory results if properly operated.
Vol. 5 , No. 6
of samples just before the water enters the first storage reservoir permits of counts being obtained before any after-growths are likely t o have occurred. The amount of available chlorin applied during the TABLEIV-PERCENTAGEOF TOTALSULFURCONDENSED IN SECOND TOWER period covered by the report of Stokes and Hachtel OF ELLIOTTAPPARATUS BURNING1.2 Cu. FT. OF GASPER HOUR Air supplied to was raised from 0.4 part per million, applied a t the apparatus bubbled start on June 15, t o 0.6 on June 23, and to 1.0 on through conc. (NH&COa renewed (NH&C03 renewed October 15. O n July 15, 1 9 1 2 , the amount was again every three hours every hour NHIOH raised, by order of the Commissioner of Health, t o 7.5 ' 0.6 0.1 6.0 0.8 ... 1.5 parts per million, and this amount has been main8.0 ... ... tained until the present time. TABLE V-PERCENTAGEOF TOTALSULFURCONDENSED IN ADDEDCONFrom June 11 t o November 1 2 , 1912, aluminum DENSER OF REFEREES APPARATUS sulfate, in amounts varying between 0.61 and I . o j Nothing added to NHlOH added to NHrOH + HzOz added grains per gallon, was applied t o the water as it ensecond condenser second condenser to second condenser tered the first storage reservoir. 1 .o 3.6 1.2 I1.l Shortly after the period covered by the report of 2.2 2.3 0.8 0.9 2.0 Stokes and Hachtel, after-growths in the storage ... 1 .o reservoir caused excessive bacterial counts. These Average 1. O 2.2 1.6 conditions maintained during the first five months Three important conditions for successful operation of the year, but about the middle of May the counts are: ( I ) A proper rate of combustion; ( 2 ) a strongly showed a marked diminution, and no further afteralkaline atmosphere in the condenser chamber; and. growths were observed, excepting during a few days (3) elimination of all rubber connections between the in September. The monthly averages of the results in bacterial burner and condenser. counts and B. coli tests, shown in a n accompanying BUREAUO F STANDARDS table, are taken from daily analyses. The counts WASHINGTON during the first six months were obtained on standard SOME RESULTS OF THE HYPOCHLORITE DISINFECTION agar a t 20' C., and during the remainder of the year OF THE BALTIMORE CITY WATER SUPPLY' a t 37" C. The B. coli averages were obtained from B y J. BOSLEYTIIOMAS AND EDGARA. SANDMAN tests made on portions of water varying b y a multiple Stokes and Hachtelz have reported the results ob- of ten from 0.001 cc. t o I O O cc., sufficient number of tained b y the hypochlorite disinfection of the Balti- tubes being used in each case t o secure a t least one more City water supply during a period extending negative and one positive test, excepting when no from the institution of the treatment on June I j , 191I , fermentation was obtained with I O O cc. The average t o October 30, 1911. They examined samples taken number of B.coli per cc. for each month was estimated from the untreated water in the impounding reservoir by considering the number of positive and negative and from the treated water after it had passed through tests in each dilution and following the method deeach of two storage reservoirs. The results of their scribed by Phelps before the American Public Health examinations showed bacterial reductions varying Association in 1907. Lactose bile was used as a n between 94.5 and gg per cent. They also showed initial medium, and Endo's agar was used for isolating average reductions in the Colon bacillus from j 7.5 the members of the B. coli group in pure culture, per cent positive tests with 0.1cc. of untreated water nearly I O O per cent successful isolations having been t o 1 2 per cent positive tests with 0.1 cc. of treated obtained by the use of this medium, whereas the water, and from 89 t o 40 per cent with 1.0 cc. The frequent encountering of spreaders on litmus agar greatest reductions were obtained with one part per and the fact that many of the acid-forming colonies million of available chlorin, when there were shown proved not t o be members of the Colon group seriously reductions from 86 per cent positive tests with 0.1 impaired the efficiency of this latter medium. No cc. of untreated water t o 9.5 per cent positive tests attempt was made until in the last two or three months with 0.1 cc. of treated water, and from roo per cent t o differentiate the four members of the Colon group; but this is now being done with the use of dulcite, in t o 37 per cent with 1.0cc. addition to the usual sugars, and morphological exThe period covered b y the following report extends aminations, and the results seem t o show a greater from January to December, 1912. I n addition t o the places sampled b y Stokes and Hachtel, we ob- vulnerability of the two B . coli organisms than of B . tained samples at the influent of the first storage aerogenes and B.acidi lactici. The results obtained by the use of the zoo temreservoir, after the water had passed through seven perature show much greater reductions in the bacterial miles of tunnel subsequent t o treatment. The time count than those obtained with the 37 O temperature, required for the water t o pass through this tunnel and we believe t h a t counts should be made a t the varies between 4.9 and 12.2 hours. While allowing higher temperature in addition t o those made a t 20'. sufficient time for effective disinfection, the taking The effects of the treatment of this water supply Paper presented at the Annual Xeeting of the American Chemical have been a very good reduction in the bacterial count Society, Milwaukee, March, 1913. of the water as i t enters the first storage reservoir, a Am. J . Pub. Health, April, 1912.
