Oct.,
1920
T H E J O - U R N AL O F I i Y D U S T R I A L A N D E N G I N E E R I - V G C H E M I S T R Y
lutiori Commission,1 after examination of a large number of samples of rain water, found t h e mean amount t o equal 0 . 3 2 p. p. m. nitrate nitrogen. Galez says t h a t no extensive beds of nitrates are t o be found in t h e United States, b u t t h a t small deposits occur in many places throughout t h e country, especially in certain caves. Nitrogen as nitrate occurs in t h e soil in varying quantities, depending upon t h e nature of t h e soil, as well as on t h e time of year, kind of crop, a n d amount of cultivation. I n general, soil contains from 5 t o 2 0 0 p . p. m. of nitrate nitrogen, though Headdon3 found as high as 60,000 p. p. m. in certain brown spots in Colorado soil. N o such soil has been found, t o t h e author’s knowledge, in any other locality in t h e United States. T h a t t h e amount of nitrates varies with t h e depth a t which t h e sample is taken is illustrated by t h e work of King and Whitson,‘ who found t h a t soil under clover and oats showed, in p. p. m. of t h e dry soil, 23.39, 18.33, 9 . 4 7 , and 7.9 for the first, second, third, and fourth foot of soil, respectively. T h a t manure piles, cesspools, cesspits, privies, sewage, and in fact any decaying animal matter .may yield enormous amounts of nitrogen as nitrates is a wellknown fact hardly necessary t o repeat. T h a t ground waters receive large amounts of nitrate nitrogen from t h e soil is not borne out by t h e work of Malpeaux and Lefort’j who found t h a t nitrates plowed t o a depth of I O in. appeared a t t h e end of 11 days in t h e top 3 in., and those plowed t o a depth of 2 0 in. reappeared in one month in t h e top 3 in. They finally con.cluded “ t h a t t h e summer rains never carry t h e nitrates beyond t h e reach of t h e roots of plants.’: Aladjem6 concludes t h a t “in waterlogged soils,” a condition obtaining in many water-bearing strata, “nitrates are decomposed.’’ Ritter7 states t h a t nitrates are reduced by t h e nascent hydrogen formed in the decomposition of peat. Tkachenkos remarks t h a t there was “little leaching of nitrates during t h e rainy periods, and this was not noticeable in any case below 2 5 t o jo cm.” Mendelejeffg gives his opinion t h a t nitric nitrogen loses its oxygen on penetrating into t h e earth. A careful study of wells10 in t h e immediate locality in which Dr. Headden reported 60,000 p. p. m. nitrate nitrogen in t h e soil, previous t o t h e appearance of the niter trouble, failed t o disclose more t h a n a trace of nitrates. T h a t surface waters do not abstract much nitrate from t h e soil is shown by t h e invariably low nitrate content of rivers and lakes a t all seasons of the year. However, by allowing rain water t o drain down through z f t . layers of soil samples contained in John C . Thresh, “Water Supplies,” 2nd Ed., p. 166. U. S. Geological Survey, Bulletin 666-2. 3 Colorado Agricultural Experiment Station, Bulletin 186 (1913). 4 Wisconsin Agricultural Experiment Station, Bullelin 93. 6 “The Circulation of Nitrate in Soils,’’ A n n . Sci. Agvmz., 30 (2). 705. “Production of Alkali in Soils b y Denitrification,” Cairo Sci. J . , 8, 274; through Chem. Abs., 10 (1916), 3128. 7 “Peculiarities o f Nitrate Formation and the Nitrate Content of Moor Soils,” Intern. Mitt. Bodenk., 2 , 411; through Chem. A b s . . 8 (1914). 1180. 8 “Observation on the Formacion and Layer Distribution of Nitrates in Soils, with Different Nitrogen Fertilizers,” Khoziaistvo, 37-40 (1912); Zhuv. O i N u . .4gvon., 14 (1913), 585; Expt. Sta. Recovd, 33 (1915), 422. 8 “Chemistry,” p . 223. l o Walter G. Sackett, “The Nitrifying Efficiency of Certain Colorado Soils,” Colorado Agricultural Experiment Station, Bdleliiz 193, 5 . 1
2
989
percolating pots, Frapsl obtained I I t o 2 0 0 p. p. m. of nitrate nitrogen. It seems possible, therefore, t h a t if a fissure should form in t h e subsoil a t a depth of 2 o r 3 ft., a ground water might be obtained which contained a large amount of nitrates derived from t h e surface soil. I n any event. t h e water so obtained could not be considered safe. I n this connection Stoddart2 describes an experiment in which sewage containing cholera spirilla was passed through a nitrifying bed of coarsely powdered chalk, with t h e result t h a t although t h e organic matter in solution was completely nitrified, the cholera spirilla could be detected in t h e effluent. T h a t t h e character of t h e soil does not have much effect upon t h e quantity of nitrate nitrogen in t h e ground water is indicated b y t h e fact t h a t ground waters in every locality of t h e state, representing soil ranging from the sand and gravel types t o t h e heavy black soil of the marshes, are found with less than I p. p. m . I n more t h a n 7 j per cent of t h e counties t h e low figure for nitrate nitrogen is below 0.1 p. p. m. These facts also oppose t h e theory t h a t there a t e mineral deposits of nitrates from which t h e nitrate nitrogen is derived. The work of W i l l i ~ confirmed ,~ by t h e following example, shows t h a t a well may be potentially dangerous, although safe bacteriologically: Dug well, in basement of a hotel in a small Wisconsin village, protected from surface washings, b u t subject t o possible pollution from outhouses; soil, sandy loam. T h e bacteriological examination showed no B. coli, only 4 bacteria growing at 37O C., and only 13 growing a t 2 0 ° C., but t h e nitrate nitrogen was 60 p. p. m. Judged bacteriologically, this is a n entirely safe water, yet there are few sanitarians who would not condemn t h e supply on t h e nitrate findings. CONCLUSIONS I - h excessive quantity of nitrate nitrogen is not a normal component of safe ground waters. 2-Many difficulties must be surmounted before i t will become possible t o set an accurate standard, b u t from t h e results here presented and from t h e evidence contained in t h e literature, a water containing j or more p. p. m. of nitrate nitrogen should be considered as a potentially dangerous supply until a sanitary survey can be made b y a competent person. 3-The nitrate-nitrogen determination should be included in every ground-water examination. I
RELATIONSHIP OF HYDROGEN-ION CONCENTRATION OF NATURAL WATERS TO CARBON DIOXIDE CONTENT4 By R. E. Greenfield and G. C. Baker STATE W A T E R S U R V E Y DIVISION,U R B A N A > ILLINOIS
The effect of hydrogen-ion concentration upon biological processes has recently been much studied b y biologists. The results indicate t h a t i t is more of a governing factor t h a n is t h e total acid or alkali content. Texas Agricultural Experiment Station, Bullelin 171 (1914), 5. John C. Thresh, “Water Supplies,” 2nd Ed., p. 167. 8 “Value of Nitrate Figure in Determining Fitness of Water for Drinking Purposes,” J . Proc. R o y . SOC.N e w S . W a l e s , 46, 408. 4 Presented a t the 59th Meeting of the American Chemical Society, St. Louis, M o . , April 12 t o 16, 1920. 1
2
T H E J O C R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol.
990
Illustrations are found in the fact t h a t the limiting Hf-ion concentration of bacterial growth is as characteristic of each species as most other general tests, and t h a t fresh-water and marine flora are found t o vary with changing H+-ion concentration. Few data are available concerning t h e H+-ion concentration of natural waters. Complete d a t a concerning t h e capbon dioxide and carbonate content of waters are, however, often available, and may be used as a basis for t h e calculation of t h e H+-ion concentration, since other salts or acids which would affect this value are rarely found in natural waters. The following mass-law equations have been shown t o be correct for carbonic acid:
Since most natural waters have a fairly high bicarbonate content and contain considerable free carbonic acid, Equation I should nearly approximate the conditions, for in the presence of appreciable amounts of both bicarbonate and free carbonic acid the ionization represented by Equation 2 would be slight. If, then, we have a record of t h e concentration of bicarbonate ion and of free carbonic acid, we can calculate t h e H+-ion concentration. According to “Standard Methods of Water Analysis,” American Public Health Association, bicarbonate is determined by titration with 0 . 0 2 N acid, using methyl orange as an indicator. This value is, of course, t h a t of t h e total concentration. It is probable t h a t t h e bicarbonate is only about 8; per cent ionized. Free carbonic acid is determined by titration with 0.045 iV sodium carbonate, using phenolphthalein as an indicator. The phenolphthalein end-point, under t h e conditions of titration, is obtained a t a H+-ion concentration of about I x 10-8. Substituting in Equation I , and solving for the amount of free carbonic acid, we obtain (HzC03
+ COz) = 3.333 X
IO-*
X (HCOC)
(3)
The free carbonic acid in t h e solution at t h e end of titration is a function, therefore, of t h e bicarbonate content, and is an appreciable quantity a t all times. I n Equation I we may therefore substitute t h e expression (COz) 3.333 X IO-^ X (Hcos-) for (H2C03 COS), 8; per cent of the bicarbonate determined by titration for (HCOs-); and express t h e COS determined as p. p. m. COz, and t h e bicarbonate as p. p. m. CaC03. The equation then becomes
+
+
(4)
If both bicarbonate and free carbon dioxide are expressed in terms of cc. of COz per liter, or in terms of p. p. m. COz, Equation 4 becomes
The two equations offer a convenient means of calculating t h e H -ion concentration of any water for 1
2
Landolt and Bornstein, “Physikalisch-Chemische Tabellen,” p. 113% Auerbach and Pick, Arb. R a i s Gesundh., 38 (1912), 243.
12,
No.
IO
which t h e content of free carbonic acid and carbonates is known. To check the accuracy of these calculations, several samples of water, from a variety of sources and varying widely in mineral and organic content, were examined. Bicarbonate and free carbon dioxide were determined according t o “Standard Methods of Water Analysis.” The free carbon dioxide titrations were continued t o a faint pink which was persistent for 3 min. The H+-ion concentration was determined colorimetrically,’ using standard buffer solutions which had been checked b y means of t h e hydrogen electrode. The results were expressed in terms of P h f , i. e., t h e negative logarithm of t h e H+-ion concentration. TABLE I-COMPARISON OF CALCULATED H + - I O N CONCENTRATION N’ITH THAT DGTERMINED COLORIMETRICALLY Res. Free Bicarb. on Con as P.p.m. ph’ pkf SOURCZ OF SAMPLE E v a p . P . p . m. CaC03 Det. Calc. Error Drift Well ... 947 10.5 408 7.8 7.70 -0.10 947 24.5 408 7.5 7.46 -0.04 947 15.0 410 7.6 7.64 0.04 947 34.0 409 7.4 7.35 -0.05 947 12.0 408 7.8 7.66 0.14 Mine Water .. . 1172 0.0 292 8.0 8.00 0.00 1172 7.0 291 7.6 7.71 0.11 1172 9.0 292 7.6 7.65 0.05 1172 14.0 293 7.4 7.44 0.04 1172 23.0 292 7.4 7.40 0.00 D r i f t Well ,... , . , , 1573 10.0 352 7.6 7.66 0.06 0.04 16.0 353 7.5 7.54 1573 7.4 7.40 0.00 1573 24.0 352 25.0 354 7.4 7.40 0.00 1573 26..0 352 7.4 7.40 0.00 1573 Swimming Pool . . . . 446 1.0 96 7.8 7.85 0.05 446 5.0 94 7.4 2.45 0.05 ,.43 0.03 6.0 90 7.4 446 7.26 0.06 90 7.2 10.5 446 90 6.8 6.95 0.15 22.5 446 Vermillion River 375 0.0 154 7.9 8.00 -0.10 0.04 7.0 152 7.5 7.54 375 15.5 152 7.2 7.28 0.08 375 7.1 7.29 0.19 I52 375 16.5 6.9 7.05 0.15 152 29.5 375 Vermillion R. Filtered 344 7 .O 132 7.5 7.50 0 00 7.0 7.10 0.10 344 22.0 130 344 38.0 130 6.7 6 90 0 20 Shallow Well. . . . . . . 459 4.0 376 7.9 7.84 -0.06 8.0 7.84 n . 16 459 4.0 374 459 6.0 374 7.9 , 7.80 -0.10 459 33.0 364 7.3 7.30 0.00 459 35.0 362 7.3 7.30 0.00 Drift Well. ... . . , 328 7.0 218 7.6 7.62 0.02 328 6.0 216 7.6 7.66 0.06 328 16.0 214 7.3 7.38 0.08 328 36.0 210 7.0 7.10 0.10 328 38.0 210 6.9 7.05 0.15 Drift Well ,,.. . , , , . 330 7.0 224 7.8 7.64 -0.16 330 9.0 222 7.7 7.57 -0.13 330 21.0 216 7.3 7.32 0.02 330 36.0 216 7.0 7.13 0.13 330 43.0 214 6.9 7.00 0.10 280 1.0 74 7.6 7.80 0.20 Reservoir. . . . 7.27 -0.13 74 7.4 8.0 280 7.18 0.18 74 7.0 13.0 280 Reservoir Filtered , , 254 5.0 64 7.4 7 38 -0.02 254 14.0 64 6.9 7.00 0.10 0.18 2.54 26.0 64 6.6 6.78 Kankakee R i v e r . . 384 6.0 100 7.3 7.47 0.17 100 7.1 7.18 0 08 584 14.0 384 25.0 96 6.7 6.94 0.24 Kankakee R . Filtered 328 6.0 78 7.3 7.40 0.10 328 17.0 80 6.9 7.02 0.12 328 44.0 80 6.8 6.66 -0.14 K a n k a k e e R . Filtered 230 16.0 28 6.3 6.62 0.32 0.15 230 27.5 26 6.2 6.35 0.04 31.0 28 6.2 6.24 230 230 1.0 26 7.6 7.57 -0.03 Ohio R i v e r , , . , , , 206 15.0 44 6.9 6.83 -0.07 206 29.0 44 6.5 6.52 0.02 0.02 206 30.0 44 6.5 6.52 Mississippi River. 225 11.0 90 7.3 7.23 -0.07
....
. ..
...
..
.. .
....
. ..
.
..
. ..
...
Each sample of water was examined without modification and also after the addition of increasing amounts of water saturated with carbon dioxide. I n taking t h e samples for titrations and for PA* determinations, no special precautions were taken t o 1
W. M. Clark and H. A. Lubs, J . B a d , 2 (1917), 1, 109, 191.
Oct.,
1920
T H E JOC.RNAL OF I-VDCSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
prevent aeration. The results of 63 such determinations are given in Table I. I n only one case was t h e difference between t h e determined and calculated Ph+ greater t h a n 0.3, and t h e mean variation is about 0.1. It will also be noted t h a t t h e wider variations occurred in t h e cases of low bicarbonate content, which is t o be expected from t h e assumptions made in t h e development of t h e equation. Somewhat larger variations are found in cases of high free carbon dioxide content t h a n in similar cases with less carbon dioxide. This is probably due t o t h e loss of carbon dioxide by aeration in t h e determination of both t h e carbon dioxide content and t h e Ph+.
From their experierlces with t h e colorimetric Ph+ determinations, t h e authors do not feel t h a t determinations can be made much more accurately than 0.2 Pj2+,using open tubes and ordinary methods of transferring t h e test sample t o t h e tube. The effect of aeration of such unstable solutions as natural waters should amount t o this much or more. It is advisable in all cases t o make several determinations. The formula cannot be applied t o waters which are alkaline t o phenolphthalein. An attempt was made t o develop such a n equation, but no waters naturally alkaline t o phenolphthalein were available for checking t h e calculations. For unusual cases of this kind and cases of low bicarbonate content, it may be better t o use some more complete and more complex equation, such :is has been developed by Prideaux.l C 0 NC L C SI 0 N S
Fairly accurate calculations of t h e H+-ion concentration of natural waters can be made from t h e simple mass law equation of t h e primary ionization of carbonic acid. Equations are developed for calculating H+-ion concentration, in which t h e carbon dioxide and bicarbonate are expressed i n t h e manner in which they are ordinarily determined. These equations are less accurate with low bicarbonate concentrations and do not apply t o waters alkaline t o phenolphthalein. X C K N 0W LEDGMEST
The authors wish t o express their appreciation of t h e assistance and advice of Prof. Victor E. Shelford, of t h e Department of Zoology, University of Illinois, who suggested t h e desirability of studying this subject , and assisted in various ways throughout t h e study. A N E W TECHNICAL M E T H O D FOR THE E S T I M A T I O N OF THE SACCHAROGENIC P O W E R OF DIASTATIC
PREPARATIONS By Kokichi Oshima TAKAMIND LABORATORY, INC., CLIFTON,N. J. Received June 1, 1920
The most practical method for t h e estimation of t h e saccharogenic power of diastatic preparations is t h a t of LintnerJ2 which is briefly outlined: 1 2
Proc. R o y . S o c . London [A], 91, 5 3 5 . 2. Drakt. Chem., 34 (1886), 386.
991
L I S T N E R METHOD
Separate volumes of 0.1,0.2, 0.3, up t o 1.0cc., of j per cent diastase solution are added t o a series of I O test tubes, each containing I O cc. of 2 per cent soluble starch solution. The tubes are allowed t o incubate for one hour a t constant temperature, a t t h e end of which time j cc. of Fehling’s solution are added t o each tube, t h e liquids mixed, and t h e tubes immersed in a boiling water bath for I O min. If, a t t h e end of t h a t period, t h e Fehling solution in t h e t u b e containing 0.1 cc. of diastase solution is just completely reduced, t h e diastatic power of t h e diastase is taken as 100. If 0 . 2 cc. reduces t h e j cc. of Fehling’s solution, t h e diastatic power is 50, etc. More exact results may be obtained, if necessary, by taking 0.1,0.15, 0 . 2 , 0 . 2 5 cc., etc., of t h e diastase solution for a series of tubes, and determining more accurately t h e amount of digest which will just reduce 5 cc. of Fehling’s solution. The following formula is used for calculating t h e diastatic power of malt by t h e Lintner scale: V : 0.1 = IOO : diastatic power V is t h e volume of diastatic solution, 0.1being t h e unit quantity used t o make t h e value of I O O on t h e Lintner scale. FAULTS O F L r K T S E R hfETHoD-This method has justly been criticized by Sherman and his associates:l first, as not being accurate, since there are only ten points on t h e Lintner scale a t which an accurate determination can be made in t h e first operation; second, the probable error of t h e method increases rapidly with t h e diastatic power of t h e sample; if t h e end-point falls between t h e last tm7o tubes (0.9 and 1.0 cc.) t h e diastatic power will be between I O and 11.1, with a relatively small ‘variation;but if it falls between t h e first two tubes (0.1and 0 . 2 cc.) t h e diastatic power lies between 50 and 100, with a very large possible error. The Lintner method can be further criticized as n o t easy or quick enough for technical purposes, particularly when a large number of tests have t o be made as a routine in factory procedure. For example, t o test I O samples by t h e Lintner method, one has t o use I O O test tubes, and different quantities of t h e diastatic solutions have t o be tested I O O times a t t h e definite intervals of time. MODIFICATIONS OF METHOD-Ling2 modified t h e Lintner method as follows: A quantity of diastatic solution is added t o I O O cc. of 2 per cent soluble starch solution in a zoo cc. flask, and kept a t a constant temperature for one hour. At t h e end of this time, 2 0 cc. of 0 . I N sodium hydroxide are added and t h e solution is made up t o zoo cc. with distilled water. After mixing, this solution is introduced into a buret and gradually run into j cc. Fehling’s solution, diluted with a little water and kept. boiling, until t h e solution just loses its blue color. If 2 5 cc. of t h e liquid (100cc. of which correspond t o I g. of soluble starch and 1 . 5 cc. of malt extract) are required t o reduce j cc. of Fehling’s solution, t h e 1
J. A m . Chem. Soc., 32 (1910), 1075.
2
Euler’s “General Chemistry of Enzymes,” 1912, p. 290.
