T N E J O U R N A L OF I N D U S 1 ' R I . l I.
448
Fic. ~-L&AD.ANTIMDNY Eurrcnc
Wmri A
B D Cansrrrumr F ~ o r ~ r mOi iF T z ~ - A x n * r u . ~ u FZG.7 - M ~ ~ n mOF LEADm Wxrcrt Is I N I ~ S O DMg-,Pb
An I I per cent tin alloy of the same series gives a hardness of 2 r . j to 22.0 Brinell (Pig. 6 ) . It will be noticed in the tin-lead-antimony alloys that, as the tin is increased I per cent, the hardness is increased half a number in each instance. Most bearing metals of the lead-base series should not contain more than i o per cent tin unless the antimony is increased proportionately. However, the alloy then becomes brittle, e of the binary alloy of lead and antimony. Above I O per cent tin, the addition of tin t o leadantimony alloys does not exert as great a hardening effect as is true when smaller percentages are added. YAGNEsIUY--hlagnesium' hardens lead when added in small amounts, usually one per cent or under. An alloy containing one-half per cent magnesium has a Brinell hardness of I j.0. Dificulty is encountered, however, in alloying these metals. Tbc alloys were made by introducing small pieces of magnesium into the molten lead until the former gradually melted and dissolved. After the magnesium is alloyed with the lead it does not oxidize rapidly, and, therefore, retains its luster and its hardness upon remelting. The writer believes the hardening constituent in this alloy t o be a substance having the composition MgZPb, which Kurnakoff and Stepanoff found to solidiiy a t j j ~ C.? ' The photomicrograph (Pig. 7 ) , although considerably scratched, illustrates the formation of this material. Ern, o s.,T (1919). 79;ab3tractedio J . Ins1 .Mdds, 81 (19i9).
I
.Meld w.
8
Grub. 2. onorg. Chrm., U (19051. 117; 46 (19051, 177.
1%
PnrMnnv CnusrALCrras
G n x w Coxsrrruanr A N D Tm C a ~ s ~ n 1 . 8
The addition of one per cent t i n t o this mixture sofiens the alloy, giving a Brinell hardness of 12.0, while 2. j per cent tin lowers i t still further t o IO.j. Between 2.j and 5 per cent tin there is a limit t o the falling hardness, and a mixture containing j per cent tin again raises the hardness to 12.0. An alloy of this composition would be rather expensive, as compared with the alloys previously mentioned, which give a greater hardness a t a lower cost. MERCURY---Arecent investigation of lead alloys, with mercury, sodium, and tin, by J. Goebel,' shows that mercury, when added t o lead, increases its hnrdness from 4 t o 9 Brinell. Any amount of mercury up t o a maximum of 7 per cent increases the hardness proportionately. The liardness of Cast lead a n d cold hammered lead is given a t the ioot of the table, t o allow of comparison in degree of hardness. THE SOLUBILITY OF MONO- AND DIAMMONIUM PHOSPHATE
By G . H. Buchanan and G . B. Winner TI:EXNICAL D B P A R T M B ~ ~ TAIISRICAN , CvnrrnHio Co., NEW yon^, N. Y. Received November 29, 1919
I n connection w.ith certain experimental work recently carried on in this laboratory, more definite information than could be found in the literature was required concerning the solubility of the two commercial 12. Vcr. dcul. Ing., M a y IO, 1919; abstracled i n T ~ r sJ O V R N A L , 11
435.
(119). 1065.
May,
1920
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
phosphates of ammonia. It therefore became necessary t o prepare solubility curves for these two salts which would be of sufficient precision for the work in hand. The temperature ranges in which we were interested were, for t h e mono-salt, from about zero t o t h e boiling point of t h e saturated solution, and from 0’ t o about 70’ C. for t h e di-salt. These solubility determinations were made with care, and with as great precision as was possible with t h e equipment in a technical laboratory. While we make no claims for t h e highest precision, we feel t h a t the d a t a are of sufficient value t o warrant their general distribution. Dammer, Abegg, a n d t h e Chemiker Kalendar state t h a t t h e di-salt, (NH4)2HP04,is soluble in four parts of cold water, a n d t h a t t h e mono-salt, (NHq)H2P04, is less soluble t h a n the di-salt. Comey adds t h a t the mono-salt is soluble in 5 parts of cold water. Olsenl gives t h e same figure for t h e di-salt, but for the monosalt he gives t h e solubility as 1 7 1 parts per hundred of water a t 0’ C. and 260 parts per hundred of water a t 31’ C.; t h a t is, the mono-salt is much more soluble t h a n t h e di-salt. The new edition of Seidell’s “Solubilities” (1919)gives a value for t h e solubility of the disalt, attributed t o Greenish and Smith, of 1 3 1 g. ( N H 4 ) * H P 0 4in I O O g. water a t 15’ C. THE
SOLUBILITY
OF
MONOAMMONIUM
( N H4) H2P 0
PHOSPHATE,
4
PREPARATION-The salt was prepared b y recrystallization of commercial mono-salt, “Ammo-Phos,” a n d analyzed as follows: Per cent NHI = 14.80; Per cent PzOs = 61.57; Ratio = 0.240. Calculated for (NH4)HzPOd: Per cent NH3 = 14.80; Per cent PzOs = 61.72; Ratio = 0.240. (By “Ratio” we m e a l the per cent ammonia divided by t h e per cent Ps0~ For the II ono-salt the “ratio” is 0.240, and for the di-salt 0.480 )
Steam un d /re WaterL in e
I
I FICA1
METHOD-The apparatus used is shown diagrammatically in t h e accompanying sketch (Fig. I). T h e temperature of t h e thermostatic bath was controlled by t h e introduction of steam or ice water, with an electrically heated hot plate as an auxiliary for t h e higher temperatures. For the very highest temperatures calcium chloride brine was used in t h e bath. This thermostatic b a t h was of large size and the water was kept in vigorous motion by a motor-driven propeller. Although hand Van Nostrand’s “Chemical Annual,” 1918.
449
controlled, no difficulty was experienced in maintaining t h e temperature constant t o within 0.5’ C., which was as precise regulation as was desired. T o each of two glass bottles of about 2 j o cc. capacity there were added water and a n amount of t h e salt largely in excess of the requirement for a saturated solution a t t h e temperature in question. One of these bottles was cooled t o about 10’ below t h e desired temperature, while t h e other was heated t o about t h e same distance above it. The bottles were now placed in t h e b a t h , the agitators introduced, and vigorous agitation a t constant temperature maintained for one hour. At t h e end of a n hour t h e agitators were stopped and samples of t h e clear liquid withdrawn in t h e special weighing pipette shown in t h e sketch
FIQ.2
(Fig. 2), care being taken t h a t the cotton filter on the end of the pipette was tight, preventing t h e introduction of crystals with t h e liquid. The agitators were again inserted and t h e stirring a t constant temperature continued while the samples were being analyzed for ammonia by distillation. At t h e time of withdrawal of t h e sample a final temperature reading was taken in t h e bottles themselves by means of a carefully standardized thermometer. This temperature was considered t h e temperature of t h e determination. If the two portions agreed sufficiently well, i t was assumed t h a t equilibrium had been reached; if they did not agree, two more samples were withdrawn, This was continued until satisfactory agreement was secured. This agreement was rarely obtained in less t h a n 2 hrs.; almost invariably the bottle with t h e rising gradient reached equilibrium more rapidly t h a n the bottle with the falling gradient. From the ammonia determinations, t h e amount of ammonium phosphate present in t h e sample, and hence the solubility, was obtained. This method of calculation is applicable, since the mono-salt is entirely stable a t solution temperatures. An analysis of the material remaining in the bottles a t the close of the series showed t h a t t h e “ratio” had not changed a t all during the experiments. The method of procedure outlined was employed for all the determinations up t o and including t h a t made a t 90’ C. I n t h e case of the measurement a t 102’ both bottles were brought t o equilibrium from below. The last point, which is t h a t of t h e boiling saturated solution, 110.j’ C., was obtained by withdrawing the samples from a saturated solution during vigorous ebullition. All thermometers used were checked by comparison with a standard thermometer. Where necessary, suitable stem exposure corrections were applied. We be-
THE JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
450
lieve t h a t the temperature measurements reported are certainly correct within = t o . j o C. E X P E R I M E N T A L DATA-when t h e solubility d a t a are calculated as percentage solubility, t h a t is, as grams of salt dissolved in I O O g. of the saturated solution, and these results are plotted (Fig. 3 ) , we find t h a t t h e points up t o and including g o o C. lie in a straight line, none of t h e determinations lying off t h e straight line by an amount greater t h a n t h e experimental error. From this straight line we derive t h e equation for t h e solubility of the mono-salt over t h e temperature range of 5' t o goo C. as follows: Solubility of Monoammonium Phosphate (g. in 100 g. of saturated solut i o i between 5"-90') = 18.0 -4- 0 45%
T h e two high temperature points fall a little below t h e straight line, probably on account of t h e difficulty in withdrawing samples from t h e highly concentrated solutions. N o determinations were made at temperatures below j o C, b u t i t is probable t h a t t h e curve could be extrapolated at least t o zero. I n Table I, which follows, are shown t h e experimental d a t a and t h e solubilities derived therefrom. Column I shows t h e percentage solubility in t h e bottle which was heated t o t h e required temperature, obtained by dividing t h e observed percentage of ammonia b y 14.80 (the per cent of ammonia in monoammonium phosphate). Column 2 gives t h e percentage solubility in t h e bottle which was cooled t o t h e desired temperature, and Column 3 gives t h e mean of Columns I and 2 . Column 4 gives t h e percentage solubility as calculated by use of t h e above formula, and Column 5 gives t h e values of Column 4 recalculated as grams salt dissolved in I O O g. water. TABLE I-SOLUBILITY OP MONOAMXONIUM PHOSPHATE, ("4)
--
Temp.
' C.
4.8 18.3 30.0 40.0 50.0 69.0 90.0 102.0 110.5
THE
-100 (1) 20.5 25.9 31.4 36.1 40.8 49.7 59.3 63.2 67.3
SOLUBILITY
&PO4 Grams Monoammonium PhosphateG. of Saturated Solution100 G Water (2) (3) (4) (5) 20.3 26.6 31.7 36.3 40.8 49.8 58.8
..
..
20.4 26.3 31.6 36.2 40.8 49.8 59.1 63.2 67.3
20.2 26.3 31.7 36.2 40.8 49.4 58.9 64.4 68.3
OF
DIAMMONIUM
(N
0 4
25.3 35.7 46.4 56.7 69.1 97.7 143.0 181 .O 215.0
Vol.
12,
No. 5
The experimental procedure was practically t h e same as t h a t used for t h e mono-salt, except t h a t two samples were withdrawn from each bottle instead of one, as formerly. One sample from each bottle was analyzed for ammonia, and, if these showed satisfactory agreement, the other pair were analyzed for PzOs by precipitation of t h e double magnesium salt. From t h e two analyses i t was possible t o arrive a t t h e amount of decomposition which had taken place. E X P E R I M E N T A L DATA-Table 11 gives t h e experimental data. The column headings are all self-explanatory, except possibly t h e last, which is intended t o show the per cent of t h e dissolved phosphates of ammonia which was present as di-salt, as calculated from t h e "mean ratio.'' This column is of value i n furnishing information as t o t h e weighting of t h e d a t a in deriving t h e solubility formula. TABLE11-THE
SOLUBILITY OF DIAMMONIUM PHOSPHATE(NHa)zHPO&
Temp. -Per O C. Up 0 10
20 30 40 50 60 70
7.69 9.89 10.54 10.87 11.45 12.06 12.58 13.07
cent NHsDown Mean
-Per Up
cent PnOaDown Mean
7.62 9.85 10.46 10.89 11.46 12.20 12.55 13.22
16.28 20.70 21.94 23.00 24.47 25.41 26.80 27.58
16.28 20.61 21.89 23.00 24.55 25.34 26.90 28.01
7.66 9.87 10.50 10.88 11.46 12.13 12.57 13.15
16.28 20.66 21.92 23.00 24.51 25.38 26.85 27.80
Ratio (Mean) 0.470 0.478 0.480 0.473 0.467 0.478 0.468 0.473
Per cent Di-salt
from
Ratio 96 99 100 97 95 99 95 97
Due t o t h e decomposition which has taken place in some of t h e samples, there is sometimes a little doubt as t o just how t h e percentage solubility should be calculated. I n Table 111 is shown in Column I t h e solubility as calculated by dividing t h e mean ammonia percentage by 25.78, t h e theoretical percentage of ammonia in diammonium phosphate. Column 2 contains t h e solubility calculated in a similar manner from t h e PzOj content of t h e solution, and Column 3 is t h e mean of Columns I and 2 . The values of Column 3 are plotted in t h e accompanying graph (Fig. 3).
PHOSPHATE,
PREPARATION-The diammonium phosphate used in these experiments was prepared by ammoniating at a temperature above 80' C. a nearly saturated solution of mono-salt, cooling t h e mixture and filtering out t h e di-salt crystals. The air-dried crystals analyzed as follows: Per cent NHa = 25.8; Per cent P,OS = 53.9; Ratio = 0.479 Calculated for (NH4)nHPOa: Per cent NHa = 25.8; Per cent P i 0 8 = 53.8; Ratio = 0.480
METHOD-Whik t h e mono-salt is very stable a t solution temperatures, t h e di-salt is much hydrolyzed, and precautions have t o be taken, particularly at higher temperatures, t o minimize ammonia losses. I n t h e apparatus used b y us i t was not possible t o entirely eliminate this loss, b u t its amount was determined in each experiment and its effect on t h e results as a whole largely eliminated by proper weighting of t h e experimental results.
FIG.3-THE
Rmprrahrrc Cenh'grcrda D I A M M O N I PUH~O~S P H A T E S
SOLUBILITY O F b ! O N O - A N D
As will be seen, t h e values between 10' and 70' C. lie in a straight line, and we derive therefrom t h e solubility formula: Solubility Diammonium Phosphate (g. in 100 g. of the saturated solution between 10°-700 C.) = 36.5 0.213t
+
T h e values of Column 4 are derived b y calculation from this formula. Column 5 contains t h e values of Column 4,calculated as grams diammonium phosphate dissolved in I O O g. water.
May,
1920
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERlNG CHEMISTRY
TABLE111-SOLUBILITY O F DIAMMONIUM PHO3PHATE -Grams Diammonium Phosphate--100 G. of Saturated Solution100 G. Water Temp. C. (1) (2) (3) (4) (5) 0 10 20 30 40 50
(in .. 70
29.7 38.3 40.7 42.2 44.4 47.0 48.8
5i.o
30.3 38.4 40.8 42.8 45.6 47.2 49.9
51.8
30.0 38.4 40.5 42.5 45.0 47.1 49.4
51.4
...
3k:6 40.8 42.9 45.0 47.2 49.3 51.4
62.8 69.0 75.2 81.8 89.2 97.3 106.0
SUMMARY
Solubility determinations made on t h e two commercially important phosphates of ammonia permit t h e derivation of t h e following solubility equations, representing t h e grams of t h e salt dissolved in I O O g. of t h e saturated solution between the temperature limits given: Solubility Monoammonium Phosphate 18.0 $- 0.455t. Solubility Diammonium 36.5 0.213t.
+
Phosphate
so goo
c. c.
IO0
c.
70’
C.
-
PEARL BARLEY: ITS MANUFACTURE AND COMPOSITION By J. A. LeClerc and C. D. Garby PLANTCHEMICAL LABORATORY, BUREAU OP CHEMISTRY, WASHINGTON, D . C. Received November 8, 1919
T h e barley crop of the United States approximates 200,000,000 bu. yearly, most of it being grown in North Dakota, California, Minnesota, South Dakota, Wisconsin, Kansas, a n d Iowa. The average annual yield per acre is about 2 5 bu. Heretofore fully onethird of t h e crop, or somewhat over 60,000,000 bu., has gone into malt for brewing a n d distilling, and a large amount is still malted for utilization in t h e manufacture of malt extract. About one-half of the crop is used directly as feed for animals, and from 2 t o 3 per cent, or approximately 4,000,000 or 5,000,ooo bu., is kept by t h e farmers for seed. This leaves a relatively small proportion of the entire crop (normally about 3,000,000 bu.) t o go directly into human food as barley flour or pot a n d pearl barley. Except during t h e war, when a large portion of t h e crop was milled i n t o a flour which was mixed with wheat flour a n d used for baking, barley has for t h e most p a r t been consumed b y man in the form of pearl or pot barley. I n this form i t has, of course, been used for many decades in Europe, particularly in Scotland where pot barley has met with special favor. About a score of manufacturers in this country are now engaged in making pearl barley, t h e total output of which before the war was ~ o o , o o o loo-lb. sacks. T h e present paper contains t h e results of a study of the method of manufacture of pearl barley a n d of t h e chemical composition of t h e various products of t h e pearling operations carried out by t h e Plant Chemical Laboratory. P E A R L A N D POT B A R L E Y
According t o McGill,‘ the reduction in weight in producing pot barleys is 46 per cent. Such barley contains from 0.89 t o 2.44 per cent of ash. The loss in making pearl barley is greater, as is evident from t h e 1
Lab. Inland Rev. Dept., Ottawa, Canada, Bulletin 329.
451
fact t h a t McGill finds t h a t pearl barley contains from 0.58 t o 1.27 per cent ash. Tibbles’ states t h a t Scotch barley is not decorticated as extensively as pearl barley. Church2 states t h a t from I O O lbs. of barley only 63 lbs. of pot barley, or about 32 lbs. of pearl barley, are obtained. Doubtless this pearl barley is t h e product resembling t h e fifth pearl barley of commerce. Gill3 states t h a t when t h e integuments of t h e barley are removed and t h e product rounded and polished t h e result is pearl barley. Sometimes in t h e process of manufacturing pearl barley, sulfur dioxide is used t o whiten t h e final product, and talc or similar substances are added t o brighten and give i t a “pearl-like” appearance. The amount of insoluble ash in normal pearl barley, which has not been subjected t o t h e treatment with talc or other mineral spbstances, is less t h a n 0.10 per cent. According t o Liverage and Hawley4 any sample of pearl barley containing a greater quantity of insoluble ash should be regarded as adulterated with mineral facing. Pluecker and Flebbs5 have shown t h a t t h e use of sulfur or talc is not for the purpose of preventing t h e growth of microorganisms, as has been claimed by some manufacturers, b u t is simply a commercial practice. MANUFACTURE
The various steps t o which barley is subjected in the pearling process are indicated in Fig. I. T h e barley as first received is passed into storage bins from which i t travels t o automatic scales. The weighed grain is sent t o t h e separator where i t is partially cleaned by screens. From the separator i t goes t o the reel,
Grader
FIG. DIAGRAM SHOWING BARLEY PEARLING PROCESS
which cleans i t more thoroughly. The cleaning is completed b y sieves and aspirators, after which t h e barley is ready for t h e pearling process. The grain 1
“Poods, Their Origin and Manufacture,” p. 471.
2 “Food,” p. 74. s “Bread Maker,” p. 75. 4 J. SOC.Chem. Ind., 34 (1915). 203. 6 Z . N a h r . Genussm.;28 (19141, 28
