Mar., 1917
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERIXG CHEMISTRY
cule does not appear t o decay uniformly, t h e portion first attacked being t h a t which yields acetic acid a n d furfurol on hydrolysis. T h e more resistant portion of t h e complex is t h a t which yields methyl furfurol on treatment with concentrated hydrochloric acid, a n d methyl iodide when heated with concentrated hydriodic acid. VI-The results obtained tend t o show t h a t t h e method described may well be used in attacking t h e problem of t h e chemical composition of wood a n d of such substances as are found in humus, i. e., humins, ulmins, huminic, ulminic a n d hymalomelanic acids. VII-Attention is drawn t o desiderata of further work. DEPARTMENT O F CHEMISTRY UNIVERSITYOF WASHINGTON, SEATTLE
THE EFFECT OF EXPOSURE ON COMMERCIAL LIMES By J. CLYDE WHETZEL Received September 22, 1916 INTRODUCTION
The object of this investigation has been t o determine t h e effect of exposure t o t h e atmosphere on t h e carbon dioxide a n d water contents o$ commercial limes, or t h e effect of what is commonly known as “air-slaking” on t h e chemical analysis. It was undertaken t o fix more accurately t h e causes of complaints on high-grade lime shipments and t o determine whether these are due t o t h e quality of lime leaving t h e plant or t o deterioration on t h e road. So far as lime manufacturers are aware, no work has been done on this subject, although it is of importance in t h e lime t r a d e especially in t h e shipment of high calcium lime for chemical use. M E T H O D A N D E X P E R I M E N T A L DATA
Obviously t h e best way of carrying out t h e tests would have been t o expose under t h e exact conditions obtained in practice, b u t this was not practicable, owing t o t h e expense a n d difficulties of using such large quantities. Accurate sampling is a n important factor in t h e analysis of lime shipments a n d is even more troublesome t h a n in t h e case of coal. The lime is in t h e form of large lumps, through which may be scattered comparatively large pieces of unburned stone or core, making i t very difficult to obtain a representative sample unless t h e lime is afterwards ground. I n order t o prevent errors in sampling, due t o t h e presence of core, t h e lime used in t h e tests was carefully selected by hand. It was impossible t o use one large sample, quartering a n d sampling a t certain periods, for as t h e lime slaked t h e sampling operations would break i t up until finally i t would become completely pulverized. This rubbing-off of t h e coating of slaked lime and exposure of quicklime would also affect t h e rate of absorption of carbon dioxide and water. The containers for t h e bulk lime samples were boxes, having six compartments, 6 in. X 6 in. X 6 in., in each of which was placed a sample. T h e careful selection gave lime sufficiently uniform so t h a t t h e samples were of t h e same composition a t t h e s t a r t , Each box was open a t t h e top, b u t a lid was supported about 6 in. above t h e box in order t o exclude dust a n d
287
dirt. I n order t o compare t h e results obtained by exposure in boxes with exposure under conditions more closely approaching actual practice, 6 open barrels were filled about a/4 full of large lumps carefully selected and exposed simultaneously. The samples of ground a n d hydrated lime were contained in boxes 6 in. X 6 in. in cross-section b u t varying in depth in order t o determine t h e protective effect of t h e upper layers of finely divided material. All the samples were placed for exposure in a small building a n d were probably in a more exposed position t h a n would be found in actual practice as t h e building was very loosely constructed a n d in addition had two open windows. Several samples were prepared b y quartering from a large pile. One was reserved for analysis a t t h e start and t h e others were placed in t h e containers, exposed a n d analyzed at t h e intervals indicated in t h e tables. Available calcium oxide was determined by the direct Solvay method of liberating t h e ammonia from a n ammonium chloride solution a n d titrating with normal hydrochloric acid. Total calcium oxide was determined volumetrically by precipitation as oxalate a n d titration with standard permanganate. I n determining carbon dioxide, t h e well-known method of absorption in a Geissler bulb was used. Water was found by difference between loss on ignition a n d carbon dioxide. EXPOSURE O F H I G H CALCIUM LUMP LIhm-This test consisted in t h e determination of t h e rate a t which high calcium l u m p lime takes u p carbon dioxide and water, Two sets of samples were exposed simultaneously: one set containing l u m p lime */d in. t o 2 in. in size a n d placed in t h e boxes, t h e other 5 in. t o 6 in. in size a n d contained in t h e barrels. T h e analyses a n d other d a t a are given in Tables I a n d 11, t h e latter giving t h e results obtained with t h e barrel samples.
--
TABLE I-HIGH CALCIUMLUMPLIME (BOXES) Per cent Complete Per cent Available Analysis CaO D r y before Exposure posed Avail. T o t a l COa Ha0 Basis 0 95.6 96.2 0.2 1.6 97.2 Si02 0.20% RzOs 0.78 11.6 96.0 7 84.8 86.5 0.8 13.6 93.9 CaO 96.17 83.1 1.0 81.1 15 30 76.2 79.4 1.7 15.5 90.3 1.01 45 68.0 72.0 2.4 21.4 86.6 0.16 60 64.7 70.3 3.1 22.7 83.6 HtO 1.56 TABLE 11-BARRELS Si02 0.56yc 1.7 96.7 0 94.9 95.4 0.2 RaOa 0.80 7 87.7 88.9 0.7 9.3 96.6 CaO 95.38 1 0 10.4 94.9 15 85 1 87 1 30 82:4 83:s 1:l 12.7 94.3 1.15 0.24 1.2 14.6 94.6 45 81 0 82.5 60 73:O 75.1 1.8 19.4 90.8 Hg0 1.74 TABLE111-MAGNESIEM LUMP LIME (BOXES) 0 ’. . . 0 . 3 3 . 2 . . Si02 0.21% 7 , 1.2 8.8 .. RzOs 0.66 .. .. 1.8 11.3 . CaO 56.64 15 30 .. .. 1.9 13.5 . MgO 38.89 ., 1.9 15.5 . coz 0.33 45 .. 60 ,. 2.6 15.6 .. Ha0 3 . 1 7 TABLE IV-HIGH CALCIUMLUMPLIME 0.907, 94.5 0.3 0.5 95.0 0 96.3 0.87 7 0.6 3.9 94.9 90.2 93.8 84. i 96.27 i.6 88.8 14 1.5 91.6 87.6 0.94 85.0 9.4 21 0.9 93.8 86. i 10.3 0.25 1.5 91.9 82.4 28 0.51 84.2 80.i 12.7 1.6 92.4 35 TABLE V-HIGH CALCIUMHYDRATED LIME 1.01% 27.3 . . Si02 0 .. .. 1.1 RzOa 1.40 25.2 .. 20 .. .. 1.4 CaO 68.05 20 . 2.3 24.6 . 1.31 20 .. ,. 5.6 23.7 ,. 1.05 Hz0 2i.25 TABLE VI-HIGH CALCIUMGROUNDLIME (10 MESH) .. .. 1.7 6.2 Si02 1.64% 0 .. ,, 2.5 12.2 .. RzO: 2.38 20 _. .. 2.9 14.4 . CaO 85.48 20 .. . . 4 . 0 18.4 .. 20
Date Analyzed (1915) 6/17 6/24 7/2 7/17 :$;6 6/17 6/24 :$:7
:4;6 6/17 6/24
$:7: 8/1 8/16 2/13 2/20 2/27 :g3 3/20 7/27 8/16 8/16 8/16
7/27 8/16 8/16 8, 16
Days
Ex-
Per cent
%?
25:
.
..
.. ..
. ..
.
.
.. .
::2
2 6 :
HzO
::E
6.19
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
---
t €XP€R/MEN7iiL
I'
FIG.I-COMPARISONOF EXPERIMENTAL CONDITIONS WITH THOSE APPROACEINGACTUAL PRACTICE ABSORPTION OF CARBON DIOXIDEAND WATER A
MAGNESIAN
EXPOSURE O F H I G H C A L C I U M L U U P LIME C S D E R WIiXTER
CONDITIOKS-A~~ t h e tests, except t h e one indicated in Table IT', were carried out in typical summer weather, while t h e present one h a d been carried o u t as a preliminary r u n during t h e previous winter, t h e only variable being t h e weather. A N D SUMMER
OF A
EXPOSURE
HIGH CALCIUM HYDRATED
LIALE-
Three open boxes, 6 in. X 6 in. X 3 in., 6 in. X 6 in. X 6 in. a n d 6 in. X 6 in. X 9 in., t h e varying dimension being t h e depth, were filled with hydrate. After 20 days' exposure, t h e contents of t h e boxes were analyzed as indicated in Table V. EXPOSURE
OF
A
HIGH
CALCIUM
IO-MESH
FIG.111-EFFECTSOF EXPOSURE ON HIGH CALCIUM AND MAGNESIAN LIMES ABSORPTION OB CARBONDIOXIDEA N D WATER
Luiw LIME-Samples of a magnesian lump ( 3 / 4 in. t o z in. in size) lime were prepared b y careful selection, placed in 6 in. X 6 in. X 6 in. boxes a n d exposed under t h e same conditions as t h e previous test with t h e results given in Table 111. OF
EXPOSURE
Vol. 9, NO. 3
GROUND
LIaiE-This test was merely a duplication of t h e previous test, using commercial Io-mesh ground lime such as is sold for agricultural purposes instead of t h e hydrate. The results are given in Table VI. RESULTS
I n order t o discuss more conveniently t h e results
---+ €XPCff/M€#TTN
obtained in t h e previous investigations, t h e y have been expressed graphically. Days exposed are plotted as abscissae for all curves, while the factors affected by exposure are plotted as ordinates. I t will be noticed t h a t t h e best line representing average conditions misses quite a few of t h e experimental points. Most of these discrepancies can probably be explained as due t o sampling and variation in t h e weather conditions of t h e different periods. COMPARISOK
OF
EXPERIMEKTAL
CONDITIONS
WITH
(Figs. I a n d 11) -Owing t o t h e greater surface exposed in t h e boxes in relation t o their volume a n d t h e lumps of smaller size, t h e box samples indicate a greater deterioration t h a n t h e barrel samples. T h e question arises as t o a comparison between t h e barrels a n d commercial bulk lime shipments. The size of lumps is practically t h e same in both cases, b u t in actual shipments t h e ratio of t h e surface exposed t o t h e air t o t h e total volume is probably less t h a n in t h e case of t h e barrels. Also t h e air does not have such free access t o t h e lime under actual conditions as it had i n t h e experimental tests. F r o m these considerations, i t is indicated t h a t deterioration in commercial shipments is less t h a n t h a t indicated b y t h e barrel samples. I n t h e statement of final results (Figs. V I and V I I ) , t h e d a t a obtained from these barrel samples are used since these represent conditions more closely approaching actual practice t h a n t h e box samples. T H O S E A P P R O A C H I N G A C T U A L PRACTICE
EFFECTS OF E X P O S U R E OK H I G H C A L C I U M A N D N A G LIMES (Fig. 111)-The deterioration of magnesian limes in shipment has little importance in practice as these find their chief use in plastering a n d are usually barreled or made into hydrate. It is interesting, however, to compare t h e rates of absorption of carbon dioxide a n d water for high calcium and magnesian limes. As indicated, t h e absorption of water is less in t h e case of magnesian limes. The water is probably absorbed b y t h e calcium oxide present a n d t h e magnesium oxide acts merely as a filler, since i t has been shown t h a t the magnesium in commercial hydrated mag-
NESIAN
J 0
Y)
20
MYS
Jb
+o
6v
60
u 0
FIG.11-COMPARISONOF EXPERIMENTAL CONDITIONS WITH THOSE APPROACHING ACTUALPRACTICE. DECREASE IN CALCIUM OXIDS CONTBNT
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
Mar., 1917
/+
/
/
/
carbonation of hydrate is of little importance commercially as i t is packed in tight bags. Ground lime is often sold in bulk a n d although t h e results obtained may not be applied directly because of t h e greater depth in actual practice, i t is of interest t o determine the approximate thickness of t h e layer affected by “air-slaking.” The depths of t h e boxes vary as I : z : 3. From t h e analyses in Table V I , the carbon dioxide absorbed varies as or as
(2.j-1.7)
0.8 :
FIG. IV-EFFECTS
OF
EXPOSURE O N LIMEIN WINTERA N D
A B S O R P T ~ OOF N
CARBOS
DIOXIDE .4ND
IN
SUMMER
WATER
nesian limes exists not as t h e hydrate b u t as magnesium oxide. T h e carbon dioxide increases a t t h e s t a r t more rapidly with t h e magnesian lime t h a n with t h e high calcium lime. K h e t h e r this is due t o t h e greater porosity of t h e magnesian lime, as t h e high calcium lime mas very dense, or t o a n inherent quality of magnesian limes, i t cannot he stated. If this is a general characteristic of magnesian limes, it may throw some light on their superior plastering qualities.
289
1.2
:
(2.9-1.7) : (‘+.0-1.7)
: 2 . 3 = I : 1 . 5 : 2.9.
These results show t h a t carbonation in bulk grouiid lime will not penetrate t o a greater depth t h a n approximately 3 in. in 20 days of summer weather since t h e weight of carbon dioxide absorbed was almost t h e same in each box. T h e foregoing conclusions evidently do not hold for hydration as t h e conditions are quite different. T h e absorption of water is so much greater t h a t t h e t o p
W 9
E F F E C T S O F E X P O S U R E O S L I X E I N TTIKTER A X D IS
(Figs. IT‘ a n d V)-It is commonly recognized among those who have t o deal with Lme t h a t its deterioration is far more rapid in summer t h a n in minter. This variation between the two seasons is shon-n quantitatively b y t h e curves in the figures indicated. There is a very great difference in t h e absorption of water in summer a n d winter, b u t less difference in t h e absorption of carbon dioxide. These results would have been predicted from t h e fact t h a t a far greater amount of mater exists in t h e atmosphere in summer t h a n in winter and t h a t the carbon dioxide content is almost constant. BUMMER
EPFECTS
OF
EXPOSURE
O S G R O U X D L I M E X S D HY-
D R A T E D LmE-The analyses in Tables l7a n d V I indicate t h a t there is little difference in t h e rates of carbonation of ground lime a n d hydrated lime although t h e apparent effect of “air-slaking” is much more marked with ground lime because of hydration. T h e
---+
CwMME8 WIN7R
-0
FIG VI-ABSORPT~OTOF CARBOYDIOXIDEAND WATERB Y BULKLIME I N WINTERA X D IT SUMMER
layer becomes completely hydrated, t h u s allowing a n y additional n-ater t o pass on t o t h e lower p a r t of t h e mass. T h e amount of carbon dioxide absorbed is comparatively small, so t h a t only a thin layer is necessary t o protect t h e remaining portion from Carbonation. T h e results obtained with hydrate likewise indicate t h a t carbonation is very superficial. CURVES FOR T H E PREDICTIOS OF THE DEIERIORATIOX BULK LIXE SHIPMENTS (Figs. VI and VI1)-It is essential t h a t these curaes shall represent actual conditions as nearly as possible. Therefore, t h e barrel tests, .which approached t h e rcal conditions more closely t h a n t h e box tests, were made the basis of t h e curves. It must be realized t h a t t h e predictions are only approximate, b u t they are on the side of safety and are likely t o indicate more “airslaking” t h a n will take place. It should also be recognized t h a t changes in weather conditions will tend t o decrease or increase “air-slaking.” Since no barrel tests were carried out in winter, OF HIGH CALCIUM
-\
&
(0
a4YS
&
&
Jo
ErRa%€O
FIG.V-EFFECTS OF EXPOSURE ON LIME I N WINTERA X D DECREASE I N CALCIUM OXIDE CONTENT
IS
SUMMER
2 PO
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 CHEMISTRY
i t became necessary t o reduce t h e box tests carried out in winter t o barrel conditions. This was done by assuming t h a t the ratios of t h e ordinates of t h e barrel curves t o the box curves, obtained in summer, would remain t h e same during t h e winter. I n t h e construction of the curves, the initial carbon dioxide, water a n d calcium oxide contents were taken as zero. This renders t h e m more easily used; i t then becomes necessary in order t o determine t h e analysis after “air-slaking” only t o a d d the water a n d carbon dioxide percentages from t h e curves t o the corresponding initial percentages as found by analysis. Similarly, t h e calcium oxide decrease as found from the curves is subtracted from t h e initial calcium oxide content. Exposure in shipment is usually for a short time so t h e time of exposure is indicated only u p t o 30 days.
FIG.
STUDIES ON THE PHENOLDISULFONIC ACID METHOD FOR DETERMINING NITRATES IN SOILS By CHARLES W. DAVIS Received March 27, 1916
-4ccording t o TiemannI5* t h e estimation of no substance has so constantly occupied the attention of analytical chemists (“literally ‘enchained’ them”) as t h e determination of nitric acid; a n d Gi1112 says, “ N O determination requires more care, or occasions more trouble in its execution, or is more unsatisfactory when finished, t h a n t h e one in question.” Three general methods are used: I-The Zinc-Iron Method. 11-The Tiemann-Schulze Method. 111-The Colorimetric Method. The last two are direct methods. Other direct methods t h a t have attracted attention are those of S c h l b ~ s i n g - R e i c h a r d t , ~Crum-Lunge,ls ~ and m r x Trommsdorf.lg These methods are best suited only when relatively large amounts of nitrates are present, and in water analysis this would necessitate the evaporation of a large quantity of water. The phenoldisulfonic acid method is another direct method t h a t has received much attention from soil chemists a n d soil bacteriologists during t h e past ten years. It originated with Sprenge120 in 1863, then for some time fell into disuse, but in 1885 it was revived by Grandval a n d Lajoux.21 Afterwards articles appeared b y Johnson123 Lind,24 Smith,26 Bartram,26 and Hazen a n d Clark.*’ Hazen a n d Clark27 as well as the German chemists have criticized the method severely. On recommendation of the Association of t h e German Experiment Stations,28 the Halle Station, after a n investigation as t o t h e most reliable method for t h e determination of nitrates in soils a n d fertilizers, selected t h e ZincIron Reduction Method as being t h e most accurate. S O U R C E S O F ERRORS M E N T I O N E D BY V A R I O U S
VII-EFFECT OF EXPOSURE ON CALCIUM OXIDECONT.%NT OF BULK LIMEIN WINTERAND IN SUMMER
I n addition t o t h e curves for total and available calcium oxide, curves giving the decrease in available calcium oxide on t h e dry basis are added. T h e calculation of analyses on t h e dry basis, i . e . , assuming the only loss in availability as being due t o carbonation, is a method satisfactory t o both t h e consumer a n d manufacturer of lime. T h e consumer pays only for the weight of lime as it leaves t h e lime plant when it contains practically no water. If it absorbs water on t h e road, it is merely converted into the hydrate, giving t h e same amount of available alkali. This slaking is of little consequence in many industries as the lime must be slaked before use. However, t h e carbonation represents a distinct loss, b u t as indicated on t h e curves calculated on t h e dry basis, there is a relatively small decrease i n t h e available calcium oxide content due t o this cause. Total calcium oxide, calculated on t h e d r y basis, will show almost no decrease; the decrease in this case is simply due t o t h e additional weight of t h e material in consequence of t h e absorption of t h e small amount of carbon dioxide. BERKELEY LABORATORY SECURITY CEMENT AND LIMECOMPAKY MARTINSBURG. WSST VIRGINIA
Vol. 9, No. 3
INVESTIGATORS
Leeds,32 FOX,*^ a n d Gill12 have found losses of nitrates on the water bath. Chamot a n d Pratt‘ report losses small on a water b a t h except when chlorides are present. Many writers have found interference in determinations in t h e presence of organic matter due in part t o the masking of t h e yellow tint, besides certain flocculents as carbon black, potash alum,2 aluminum cream, copper sulfate, etc., used t o precipitate clay a n d organic matter occasions considerable loss in nitrates. Gill12 a n d Weston83 found losses in the presence of carbonates, while Chamot a n d Pratt’ claim losses of nitrates insignificant except when the quantities of nitrates are low or t h e alkalinity of t h e solution very high. Lipman a n d Sharp12 and Kelly7 call attention t o great losses in t h e determination due t o presence of sulfates either in t h e solutions, or when sulfates as potash alum are used as a flocculent. 1 Part of Thesis submitted in partial fulfillment of the requirement for the Degree of Doctor of Philosophy in Agronomy in the graduate school of the Iowa State College, 1916. Numbers refer to Bibliography at end of article.
*
