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 C H E i M I S T R Y .
Aug., 1911
TABLEB (Co%finued).-V~i~ SAMPLES.
4?
C
2381 2382 2388
E 5th
2637 2638 2639 2640 2641 2642
w 5th
3.45 0.56 15100 5.82 0.59 14530 8.28 0.59 14040
15680 15550 15410
12570 13620 12880 13860 8650 11960
15670 15630 15720 15630 15490 15670
C 2572 Stove ....,... 1.70 6.45 79.33 12.52 0.57 13410 C 2573 Chestnut .... 2.10 6.38 76.14 15.38 0.54 12830 C 2574 Pea.. .. .. . . . 2.51 7.20 71.14 19.15 0.56 12230
15560 15470 15540 15640 15750 15780
2.82 5.85 87.88 2.06 6.92 85.20 1.39 7.27 83.06
6th W 8th
2.50 2.06 2.80 2.45 1.94 1.81
E 5th
w 4th W 6th W 3rd 1st
w
6.47 7.46 6.93 6.44 7.85 7.35
73.27 78.88 74.06 80.95 50.17 69.37
17.76 11.60 16.21 10.16 40.04 21.47
0.52 0.52 0.34 0.50 0.35 0.40
TABLEB (Continued) u
B 4
0 C
C
n"
i
.
C 2575 C 2576 C 2577
Buckwheat Rice ......... Barley .......
C C C C C
2776 2777 2778 2779 2780 C 2781 C 2782 C 2783
Broken.. . . Flat jig stove Stove. , Chestnut . Pea. . Buckwheat Rice. . Barley.. . . . .
. . . .. . .. .. .. .. . . . . .. ..... .
2.95 2.66 2.65 3.04 2.92 2.89 2.92 2.68
5.57 6.40 6.12 5.84 6.42 6.64 5.92 6.46
80.75 74.27 78.35 77.67 72.60 72.60 74.52 74.59
10.73 16.67 12.88 13.45 18.06 17.87 16.64 16.27
0.55 0.56 0.53 0.56 0.54 0.54 0.52 0.55
13660 12670 13290 13250 12440 12490 12690 12750
15530 15570 15520 15640 15590 15610 15600 15580
2792 2793 2794 2795 2796 2797
Stove ........ Chestnut Pea ......... Buckwheat Rice ......... Barley ..,....
2.25 2.12 1.86 0.66 1.96 2.28
8.09 6.78 6.67 6.25 7.07 6.77
78.73 78.18 71.66 75.58 71.30 75.21
10.93 12.92 19.81 17.51 19.67 15.74
0.54 0.51 0.50 0.46 0.49 0.47
13760 13350 12230 12640 12160 12810
15670 15590 15670 15630 15550 15530
....
1.39 6.45 73.86 18.30 0.58 12490 2.13 6.69 71.40 19.78 0.57 12290 2.44 6.90 69.80 20.86 0.50 12120
of the proximate analysis as well as those of the actual calorimetric determination are reflected in the heating value per pound unit coal. For the sake of comparison the values published b y Palmenburg (Loc. cit., p. 406) have been calculated t o heating values per pound unit coal, b y the formula of Parr and Wheeler. The values published have:been assumed t o have been determined on, or calculated to, the dry coal. TABLEC.
No. 328 330 330 330 333 438 440 442 444 462 399 400 494
Heating value Determination Per cent. per lb. unit coal from (Ash. (Parr and Wheeler). which taken. 26.58 14790 second 20.19 , . 14970 Brst 20.19 15080 second 20.19 15030 mean 14.36 14790 mean 14.29 14840 mean 25.20 14990 mean 20.26 14890 mean 23.62 14900 mean 15.22 15010 mean 21.23 14880 mean 21.67 14940 mean 8.99 15130 mean
559
I t may be well to note that the above results were obtained with the Atwater calorimeter, the water equivalent of which was determined b y burning samples of naphthalene and hippuric acid as recommended by Atwater in his original artic1e.I Although having no direct bearing on the method, i t may be of interest t o state here that this particular Atwater calorimeter has been slightly modified b y us for convenience in manipulation. The screw cap socketed for a spanner on the original apparatus, has been replaced b y a screw cap bearing a hexagon head. Thus b y substituting a box wrench for the original spanner, the annoying tendency t o slip has been removed. The stirring motor together with a n upright some 42 cm. high have been mounted upon a piece of oak board, free t o move upon the calorimeter table. This upright supports a walking beam, one end of which is connected by a driving rod direct t o the crank of the motor, wh(1e the other end of the beam may be thrust into the ring of the stirrer, thus giving the stirrer a positive movement much t o be preferred to the more or less uncertain motion imparted t o it by the usual string and pulley device. LABORATORY OF THE PHILADELPHIA & RE.4DlNG COAL AND IRONCOMPANY. POTTSVILLE, PA.
PREPARATION OF NEUTRAL AMMONIUM CITRATE SOLUTIONS BY THE CONDUCTIVITY METHOD. B y ROBERTA. HALL. Received M a y 8. 1911.
I n their investigations of the proportions of aqueous solutions containing ammonia and citric acid,' Hall and Bell found that the neutral point of the solution could be detected b y conductivity measurements, and this suggested the application of the conductivity method as a possible means of preparing the neutral ammonium citrate solution required in fer- + tilizer analysis for the determination of the citrateinsoluble phosphoric acid in a fertilizer. In order t o ascertain the possibility of readily and easily preparing neutral ammonium citrate b y the application of the conductivity method the following experiments were made by the author of this article. A citric acid solution was prepared of such a citrate content t h a t when neutralized b y ammonia its specific gravity would be greater than I , 09 a t 20'; that is, 370 grams of pure citric acid3 were dissolved in ammonium hydroxide of 0.90 sp. gr. and water, unti1 the solution was near the point of neutrality, yet leaving the solution acid to litmus paper. Care was taken that the volume was not over one liter. The solution was allowed t o stand over night t o cool. It was again tested with litmus paper t o see t h a t it was distinctly acid. Also, small portions, one t o two cc., were withdrawn with pipettes and roughly titrated with a diluted ammonia solution in order t o ascertain the apprcximate amounts of ammonia solution necessary t o make the citrate solution distinctly alkaline t o litmus. The diluted ammonia, solution used was prepared b y taking the concentrated am1 J. A m . Chem. SOC., 26, 2 I b i d . . 33, 711.
659.
a Method of Analysis; Bull. 107, Bureau
of Chemistry, p. 1.
560
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!VGINEERING C H E M I S T R Y .
monium hydroxide, sp. gr. 0.90, and diluting exactly ten times, that is, roo cc. were diluted to one liter. A sufficient amount of this solution was prepared to have enough for the making of the solution for the conductivity measurements and also for addition to the larger bulk of the acid ammonium citrate solution,
Aug., 1911
of the calculated amount, as shown by the conductivity measurements, for complete neutrality. 100-cc. lots of the nearly neutralized ammonium citrate solution were withdrawn with pipettes and put in zoo cc. volumetric flasks. Definite amounts of the diluted ammonia solution were measured into these differ-
Aug., 191 I
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 C H E M I S T R Y .
ent flasks. Water was then added t o the mark, the solution thoroughly mixed, and the flasks placed in a n electrically controlled thermostat. The temperature of this thermostat was maintained a t 2 5 O , plus or minus 0.01'. When these solutions had come t o the temperature of the bath their conductivities were determined with a Wheatstone bridge in the usual way. The conductivity cell used was the H. C. Jones type for concentrated solutions. The conductances were plotted against the cc. of the ammonia solution used. It was easy t o read from the curve thus obtained the number of cc. of the ammonia solution needed to neutralize exactly loo cc. of the acid ammonium citrate solution used. This amount of the diluted ammonia solution was then measured into a 2 0 0 cc. flask captaining I O O cc. of the citrate solution and water added t o the mark. After thorough mixing, the flask was placed in the bath and allowed t o come t o bath temperature. I t s conductivity was then ascertained. I t s conductance showed it to have the amount of ammonia necessary for exact neutralization. The solution, when tested with corallin, methyl orange, methyl red, and neutral litmus paper (Squibb's), gave no evidence of the presence of excess of either acid or base. Also, the solution was shaken out with chloroform, the chloroform separated from the citrate solution and shaken with water and the water tested for ammonia.' No ammonia was found. Hence it was concluded t h a t a neutral ammonium citrate solution had been prepared with accuracy and certainty. Specific gravity determinations were also made of the solution used in these conductivity determinations and the densities plotted against the cc. of ammonia. The curve showed t h a t the neutral solution as prepared b y the conductivity had the highest specific gravity.' In Table 1 is given the data obtained in these measurements, and in Fig. I the conductances are plotted against the cc. of ammonia solution used: TABLEI Solution N o . 1 ...........................
2........................... 3...........................
4 ........................... 5 ........................... 6 ...........................
7 ...........................
Cc. ammonia
0.00 6.00
18.00 24.00 30.00
40.00 20.30
Conductivity.
0.004085 0.004353 0.004900 0.004997 0.004991 0 ..004980 0.004999
The neutral solution as prepared above had a specific gravity greater than I . og at 20'. It was therefore a n easy matter t o dilute with distilled water and in the usual way bring t o the required density. I n order t o investigate the possibility of the use of the conductivity method of preparing neutral ammonium citrate solution b y the chemist who has not the use of a n electrically controlled thermostat, or a thermostat regulated b y any other method wherein a constant temperature is secured, a series of experiments were made in which the use of the regulated thermostat was dispensed with; t h a t is, the elec1
Hall and Bell, Loc. cit.
56 I
trical control was cut off and the temperature of the bath was allowed t o vary with that of the room. However, a time for experimentation was chosen so t h a t there was a minimum of variation of room temperature. I n brief, the experiments were conducted under such conditions as can be had in any laboratory where a room fairly well protected from the usual weather variations and from the presence of those entering and leaving the room during the time of the experiment can be had. In the place of the thermos t a t a t u b of water could have been used for the bath. The solutions were prepared as above, placed in the bath and allowed to come t o the temperature of the bath. Erlenmeyer flasks of suitable volume and 'of such sized mouth as to admit of easy entrance of the electrodes of the cell were placed in the bath, so that when the solutions were being changed in the cells the electrodes could be placed in these flasks and be kept a t the temperature of the bath, thus preventing the slight lowering of temperature due to the evaporation of the water on the electrodes. The conductivity measurements were made as rapidly as possible (each series was run in less than one and one-half hours), the cells and electrodes being carefully washed each time with the new solution. This rinsing was repeated three times for each change of solutions. During the short intervals of waiting necessary for the cell and its solution t o come to bath temperature again after the handling the conductances were computed and the curve plotted, so that as soon as possible after the last reading was made the last point in the curve was located and the curve completed. It was found further that by plotting the bridge readings against the cc. of ammonia solution used t h a t the same results were obtained as b y plotting the Conductances against the cc. of ammonia solution. I n this way it was possible to make the series of six measurements in a very short time, usually less than one and one-half hours being required, and thus minimize the probability of any great change of room temperature. From the curve was read the amount of ammonia solution needed t o be added t o I O O cc. of the acid ammonium citrate in order exactly to neutralize it. This amount of ammonia was run into a 2 0 0 cc. flask containing the solution previously measured out, water added t o the mark, and the solution thoroughly mixed. The flask was then placed in the bath and brought to the temperature of the bath. The conductivity measurement was then made. It was found t h a t the bridge reading obtained corresponded exactly t o the bridge reading on the curve for neutral ammonium citrate solution. The same amount of ammonia was then run into another I O O cc. lot of the ammonium citrate solution and this solution made up t o a specific gravWhen these solutions were tested ity of 1.09 a t 20'. with indicators and chloroform, as above, they gave no evidence of containing either acid or free ammonia in excess. The bath was now brought again t o a temperature of 2 j' and maintained there b y the electrical control
562
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 C H E M I S T R Y .
while the conductivity measurements were repeated. These gave a curve showing the neutral point to be the same as t h a t found a t room temperature. In Table I1 are given the data of the measurements made a t room temperature. In Fig. 2 the bridnereadings are plotted against the cc. of ammonia solution used:
Fig, 2.
Aug.,
1911
TABLE11. 1
Cc. ammonia. 0.00
4
10.00 18.00 24.00
Solution No.
....................... 2 ....................... 3 . ...................... 5
....................... .......................
30.00
6 7
.......................
36.00 20.80
.......................
Bridge-reading. 49.40 52.01 54.09 54.80 54.75 54.70 54.84
Fig. 2
Fig. 3 ,
Fig. 4
Fig. 5 .
Fig. 8.
Fig. 7.
Pig. 1 2 .
Fig
13,
Fig. 14.
Fig. 15.
Fig
16
Fig. 18.
Fig. 1 7
Fig. 19
GBNEWL ACPANGEMENT a= UECT~NCR BLOC 36'. pa'
PRECIPITATIONPUNT BALAICLALA Cm.CapPEcCo COCAU. C A L
I
Fig. 24.
Fig. 29.
Aug., 1911
T H E .70URAV\;,4LOF I h ‘ 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 .
An effort was made to ascertain the possibility of preparing a neutral citrate solution b y adding an excess of ammonia and afterwards removing this excess b y extractions with chloroform.’ Although repeated extractions were made, there was always free ammonia remaining in the citrate solution. This was t o be expected, as the ammonia is so much more soluble in water than in the chloroform. Moreover, had it been possible t o extract all the free ammonia from the solution the chloroform that would have remained in solution in the citrate solution would have precluded the use of this method for the preparation of neutral ammonium citrate for the fertilizer analysis, as the chloroform would be decomposed, forming free hydrochloric acid, which would interfere with the determination of the citrate insoluble phosphoric acid. CONCLUSION.
It has been shown t h a t the conductivity method of preparing neutral solutions is applicable to the preparation of exactly neutral ammonium citrate solutions of such a density that they can, after neutralization, be diluted with distilled water and brought t o a density of I . 09 a t zoo. This method can be applied under conditions such as can easily be obtained in any laboratory and therefore seems worthy of adoption as an “Official Method” of preparing the exactly neutral ammonium solution required in fertilizer analysis for the determination of the citrate insoluble phosphoric acid content of the fertilizer. For the regulated thermostat there may be substituted a tub of water. However, a thermostat of constant temperature is preferable, for then there is no necessity of the measurements being carried out so quickly as when the measurements are made in a bath a t room temperature. DEPARTMENT O F CHEZIISTRP, UNIVERSITY OF SORTH CAROLISA CHAPFLHILL 9 C
A POLARISCOPIC METHOD F O R T H E DETERMINATION O F MALIC ACID AND ITS APPLICATION IN CANE AND MAPLE PRODUCTS. B y P. A. YODEK.
Received April 1 7 , 1911.2
I n the following report there is developed, from extensive original data, a polariscopic method for the estimation of active malic acid which is applicable to a wide range of mixtures without previous isolation or purification of the malic acid. Methods are also developed for a partial separation of malic acid which makes the method of estimating it applicable t o a n additional wide range of natural products and artificial mixtures. Some applications of the method in the examination of cane and maple syrups are reported. Supplemental t o this are notes on a method for tartaric acid, less fully worked out, and a plan for applying these methods t o determine both these acids in a mixture of the two, without previous separation of them. This was Hall and Bell, Loc cit. This paper is an abridgment of a paper by the author on the same subject presented a t the 42nd general meeting of the American Chemical Society, July 12. 1910.
563
worked out incidental to an investigation on the acid constituents in sugar cane. The methods described in the literature for determining the organic plant acids are in many particulars far from satisfactory, even when applied to fruit juices or fermentation products, for which most of them were worked out. I n sugar cane juice and its products, new difficulties are encountered. With perhaps none of the commonly occurring organic plant acids have the methods hitherto in use‘ proved more unsatisfactory than with malic acid. In the cane juice, besides the inconvenience occasioned by the large amount of sugar present, the aconitic acid, which is a prominent constituent, introduces special difficulties in that its salts with such bases as are usually available for the separation of organic acids are not widely different from those of malic acid. Therefore a method for its determination which is a t once accurate and applicable t o a wide range of mixtures will doubtless be welcomed by the many analysts who have occasion t o deal with products containing it, such as maple products, fruit juices, fermentation products, etc., as well as by investigators who seek t o ascertain for the first time its occurrence or nonoccurrence in various substances. Among analytical operations described in the literature referring to malic acid are several processes, depending upon group reagents, yielding results that are arbitrarily reported as malic acid or more properly as “ malic acid values,” without presuming in them any ultimate determination of malic acid. Thus a convention has been in vogue in cider and vinegar analysis of computing and reporting the total nonvolatile acids, or organic acids, as malic acid.2 In the older text-books the method of R. Kaysers was commonly given for malic acid in wines. This method is based upon the assumption, t,hat the malate is the only soluble salt of a non-volatile organic acid that barium chloride forms in wine in the presence of sodium carbonate and freed from alcohol. This is true, however, only of a relatively narrow class of natural products. Succinic, citric and aconitic acids besides others all form water-soluble salts with barium, hence in their presence this method could not be applied. A method somewhat similar to the last but with calcium substituted for the barium, as proposed b y Leach4 for wine and vinegar analysis, has similar limits t o its range of usefulness. I n the examination of maple products and suspected adulterations and imitations of maple products i t is usual to determine the amount of calcium precipitated b y the neutral solution in the presence of alco* Schmidt and Heipe, 2. anal. Chem.. 21, 534-541 (1882); Bwll. 107, (revised). Bureau of Chem., U. S. Dept. of Agr., p.. 80; G. Joergensen, 2. Cnters. .Vahr.-Genussm.. 13, 241 (1906): 17, 3 9 6 4 1 2 (1909); Chem. A b s . , 1, 1448 (1907); 3, 1781 (1909); F. Xlutellet, Annales des Falsifications, 2, 383-6. Some notes on such means of separating organic acids and on estimating others of them than malic acid forms the subject of a separate paper. 2 Allen’s ”Commercial Organic A4nalysis,”4th E d . , 1, 187, 5 0 5 . 3 Ibid., 3rd E d . . 1, 512; Konig’s Untersuchwng landm. zc. gewerblich wicktiger S t o f f e . 2nd Ed., p. 588. (The newer editions of both these works omit Kayser’s method for malic acid.) Leach’s “Food Inspection and Snalysis,” 2nd E d . . 1909, pp. 702, 768.
