June, 1917
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
advantages t o this procedure. I n the process of filtering a deeply colored solution there always remains a small quantity of t h e color in t h e filter paper; a n d in t h e second place if a large number of samples are being handled each day, t h e time factor is worthy of consideration. The quantity of ammonium salt required is dependent upon what alkali is used for t h e neutralization of t h e excess acid. If ammonium hydroxide is used, 5 cc. of a saturated solution of ammonium chloride will be found sufficient t o hold in solution t h e magnesium which will be present in from 20 t o 50 cc. of most waters. If sodium or potassium hydroxide is used there mill be required a larger quantity of t h e ammonium salt, owing t o t h e result of mass action between t h e alkali hydroxide a n d t h e ammonium salt, a n d t h e amount required will be in proportion t o t h e amount of alkali added in excess. T h e addition of t h e ammonium salt is made after t h e neutralization and before t h e final dilution. The writer has found this slight change in procedure quite serviceable in routine water analysis. WISCONSINSTATE I,ABORATORY OF HYGIENE UNIVERSITY OF WISCONSIN, ADIS IS ON
LEVULOSE THE PREPONDERANT SUGAR OF APPLE JUICES By JOHN R . EOFF, JR Received February 19, 1917
Thompson and Whittier* state t h a t levulose is the predominant sugar of apple juice a n d give t h e percentages of sugars found in t h e juice of one variety of apple a t different stages of ripeness. Browne3 states t h a t apples contain levulose in excess of dextrose, but gives no figures. Worcollier4 says t h a t dextrose a n d levulose compose 6 0 per cent t o 9 j per Sample Variety of Apple Analyzed NATIVE 1916 Mother. . . . . . . . . . . . . . . . . . 10116 Grimes (Golden) Arkansas. Limbertwig. . . . . . . . . . . . . . York Imperial.. . . . . . . . . . . 10/24 Lankford. Gano .................... Peck. . . . . . . . . . . . . . . . . . Northern S p y . . . . . . . . . . White Pippin.. , . , . . , , . . Plumb Cider.. . . . . . . . . . . . 10127 Rome (Beauty). Yellow Newton.. . . . . . . . . . S t a y m a n Winesap.. , , , , , Ben Davis . . . . . . . . . . . . . .
. . . . . .. .. .. .. .. .. .. .. .. .. . ...............
..........
..
FRENCH
Acidity Graviry of Juice of Juice Temp. (a) Brix C. 47.0 11.8 23 63.5 12.3 23 69.0 11.9 23 66.0 11.: 23 67.5 ll.X 23 59.0 12.0 24 63.0 11.21 23 67.5 12.0 23 56.0 12.0 23 50.5 11.1, 23 i3.5 10,s 23 44.5 11,s 22 53.0 13.1 22 72.0 13.5 22 52.0 11.21 22
Bonne-de-Frieulles . . . . . . . . 11;2 29.0 16.3 16.0 11.1 AmBre-de-Berthecourt. . . . . Godard. 30.0 15.4 D'Arroles, . . . . . . . . . . . . . 148.0 14.2 AmPre-du-Surville ......... 41.5 11.7 ( a ) Cc. N/10 alkali per 100 cc. of juice. ( b ) Clerget. (c)
...............
1
3 4
L =
D = - -b'
a-u'
(b) 2.2 3.6 1.5 0.8 1.1 2.4 1.3 2.4 2.5 2.4 0.6 2.2 3.5 3.2 1.2
...
5.9 6.3 6.2 5.9 5.9 6.1 5.9 6.3 5.9
...
3.7 2.7 0.6 1.9 3.1 3.1 1. o
2.6 8.5 2.9 22 22 1.0 1 .o 6.6 22 3.6 3.6 7.1 2.2 21 6.8 2.4 0.4 1.2 0.2 21 Acid inversion, Cu reduction.
Published b y permission of the Commissioner of Internal Revenue. Delaware College Agricultural Experiment Station, Bull. 102, 19 13. J. Am. Chem. Soc., 23, 8 i i . Ann. f a l s . , 2, 425-7.
1,317
0.794
0.624
id) 5.8 5.8 5.8 5.0 6.3
(c)
2.3 3.9 1.5 0.7 1.3 2.6 1.8
(e) 6.4 6.4 6.2 5.4 6.6 6.8 6.0 6.2 i.1 6.8 6.7 6.8 6.8 6.8 6.5
(d) 1.7 0 .5 2.6 3.5 2.5 , . .
3.2 3.3 1.7 2.2 1.4 1.4 1.8 2.1 2.5
(e) 2.2 1.2 3.0
;:;
2.2 2.6 2.3 1.7 1.8 1.6 1.9 2.4 2.4 2..
TOTAL (d) 9.7 9.9 9.9 9.3 9.9 l0:4 12.0 10.4 10.5 i,? 9.1 11.2 11.6 9.6
3.0 13.8 1.8 9.1 1.5 2.0 12.2 1.5 2.5 11.3 2.3 7.2 2.2 9.7 2.3 7.6 (d) Optically. (e) Browne.
8.9 2.3
S =a-b
-L
APPLE TUICES PERCENTO F SUGARS AS DETERMINED
SUCROSE LEVULOSE DEXTROSE
cent of t h e sugars present in apple juices a n d in t h e proportion of 2.8 to I O times as much of levulose as of dextrose. As far as t h e author is able t o find out, no systematic investigation of a n y large number of apple juices from various varieties of apples grown in different localities has been made t o prove or disprove t h a t levulose is always in greater quantity t h a n t h e other 2
sugars present in such juices. The object of this paper is t o give t h e results of some work done on various varieties of apple juices, and is t h e first of what t h e author hopes t o make a series of several papers treating of t h e amounts of t h e different sugars in apple juices. Twenty varieties of apples were secured through t h e courtesy of t h e Virginia Agricultural Experiment Station, a t Blacksburg, Va. The fruit had been grown in t h e orchards of t h e station, carefully selected as representative a n d t r u e t o name, a n d picked a n d immediately shipped when market-ripe. Fifteen of t h e varieties were native and were t h e commercial apples best adapted t o t h e section where grown. Five varieties mere French cider apples, and h a d been gathered from trees 14 years old. The juice was thoroughly expressed from t h e fruit after grinding in a small meat grinder, a very efficient hand press being used for t h e purpose. The analysis was undertaken immediately after pressing. T h e method followed in t h e examination of t h e juices was substantially t h a t detailed by Thompson and Whittier: 26 g. of juice were weighed into a IOO cc. flask, clarified with a slight excess of lead acetate, t h e lead being removed with a slight excess of potassium oxalate after completing t h e volume. I n some instances alumina cream was used in conjunction with lead acetate. T h e solution was polarized in a zoo mm. t u b e a t zo and 8;" C. before and after inversion with invertase, t h e instrument used being one of Schmidt and Haensch's make, Yentzke scale. The calculations were made by t h e following formulas:
-
i\NALYSES O F
587
2.7
/.4
PERCENT OF SUGARS OCCURRING AS
Sucrose Levulose Dextrose 22.7 59.8 17.5 5.0 36.4 58.6 15.2 58.6 26.2 8.6 53.8 37.6 11.1 63.6 25.3 12:s 20.0 24.0 22.9 7.6 22.7 31.2 27.6 12.5
56:7 52.5 59.6 56.2 74.7 62.9 52.7 54.3 61.5
3018 27.5 16.4 20.9 17.7 14.4 16.1 18.1 26.0
18.8 11.0 29.5 19.5
61.6 72.5 58.2 60.2 74.2
19.6 16.5 12.3 20.3 23.7
2.1
Where a a1
S
=
= Direct reading a t 20° C. = Direct reading a t 87' C.
Per cent sucrose. I,
=
b = Invert reading a t 20' C. b' = Invert reading a t S i o C.
Per cent levulose.
D = Per cent dextrose.
The different sugars were also determined by Browne'sl method using Munson a n d Walker's table,2 for t h e reducing sugars a n d t h e following formulas for t h e calculations: 1 2
J . A m . Chem. Soc.. 28 (1906). 439. U. S. Bureau of Chemistry, Bull. 107, rev., 243-51.
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
where x = Per cent dextrose.
y = Per cent levulose
R = Reducing sugars as dextrose. P = Polarization of a sucrose normal weight on a saccharimeter, 200 S = Sucrose
c.
The d a t a obtained froni t h e investigation will be found in t h e accompanying table. I t will be noticed t h a t in every instance t h e amount of levulose exceeds t h e combined amounts of t h e other sugars present, a n d though this work is by no means exhaustive, i t b y so much substantiates t h e statements previously made t h a t levulose is t h e sugar predominating in apple juices. U. S. INTERNAL REVENUELABORATORY D. C. WASHINGTON,
THE INFLUENCE OF CALCITE INCLUSIONS ON THE DETERMINATION OF ORGANIC CARBON IN SOILS By
EDMUND C. SHOREYA N D WM. H. FRY Received February 28, 1917
I t has been pointed out by hlcCaughey and Fry1 and by Robinson2 t h a t soils derived from limestones, especially those of t h e Limestone and Uplands Province, are peculiar in containing inclusions of calcite and iron oxide in quartz. I n a recent mineralogical examination3 of a number of samples of Hagerstown silt loam, one of t h e important soil types of t h e Limestone a n d Uplands Province, t h e almost universal presence of calcite inclusions in quartz was again brought t o our attention and some consideration has been given their significance. Quartz is among t h e most resistant soil minerals and i t is evident t h a t crystals of calcite inclosed in quartz, so long as such quartz particles were intact, could have no agricultural significance. I n fact, such calcite Bureau of Soils, Bull. 91, 1913. Department of Agriculture, Bull. laa, 1914. a T h e identification of calcite inclosed in quartz in the soils examined was carried oiit in the manner usual in work with the petrographic microscope. The soil was mounted in an oil having a known refractive index, preferably very close to the index of quartz as this mineral is thereby rendered practically invisible when the analyzing nicol is removed from the microscope tube. When the nicols are crossed the calcite grains are readily “spotted” by their high interference colors. T h e work from t h a t point on is simply confirmatory. Rarely the calcite grains show crystallographic outlines and in these cases the index of the grain can be determined by rotating the stage until the grain disappears and comparing the actual index thus noted with the index calculated for a calcite grain having the same orientation as the grain under consideration. Thq two indices thus obtained should of course be identical. T h e chief difficulty in this procedure is t h a t often the interference figures of the quartz and calcite mutually clash, but with patience grains can be found showing the figures with sufficient clearness to enable the grain t o he roughly oriented. When all the conditions are favorable as outlined above, there is no doubt as to the identity of the grains under observation. I n other cases the extremely high interference colors practically settle the question, the only probable source of error being the confusion of calcite with dolomite, but so far as any analytical error introduced by the inclusions in quartz are concerned i t makes no difference whether they are calcite or dolomite. So far a s is known a t present there is no other method of determining roughly the quantity of a given mineral on a slide except actual count of sized material, or measurement of heterogeneous material, and in this latter case, as in rock sections, the material must he of uniform thickness. I n the case of inclusions such as those under consideration i t is obviously out of the question to apply either of the methods mentioned above, and consequently the quantity of the inclusion present cannot be stated in quantita. tive terms. 1
3
Vol. 9 , S o . 6
probably .would be a less likely source of soluble calcium in a soil t h a n t h e calcium-bearing silicates. The analytical significance of such calcite inclusions cannot, however, be ignored, for there are several determinations commonly made b y agricultural chemists where their presence would introduce a n error. I n carbonate or‘carbon dioxide determination, where t h e carbon dioxide is set free from carbonates by a stronger acid, it is evident t h a t any carbonate completely protected by inclusion in quartz would not be determined by a n y of t h e methods now in use. Since, however, such calcite or carbonate has no immediate agricultural significance, this error may be ignored where t h e determination is made for t h e purpose of indicating proper agricultural practice. Among the methods used t o determine approximately t h e organic matter in a soil is one t h a t depends on determining t h e total carbon and calculating this t o organic matter b y t h e use of a n empirical factor. Two methods are in use for determination of total carbon: combustion in a current of oxygen with or without copper oxide; or, oxidation of t h e organic matter t o carbon dioxide b y some moist oxidizing reagent a n d determination of t h e carbon dioxide evol.i-ed by one of t h e usual methods. I n both cases determination of carbon dioxide evolved from a n y carbonate present is made on a separate sample a n d t h e quantity so obtained deducted from t h a t total obtained on combustion, the difference being stated as organic carbon. The first method, usually designated t h e cupric oxide method, is not subject t o much modification a n d is considered a n absolute method b y which others are t o be judged. On account of its tedious character, however, other methods, usually designated moist combustion methods, have been devised. These usually depend on t h e oxidizing effect of boiling concentrated sulfuric acid t o which potassium dichromate has been added; a n d proposed modifications of this method relate chiefly t o t h e method of determining t h e carbon dioxide a n d t h e design of t h e apparatus used. I n determining t h e organic carbon in a soil containing inclusions of calcite in quartz by either of these methods, i t would seem from theoretical considerations t h a t in t h e case of t h e moist combustion method the carbon dioxide of included calcite would not be set free, while in t h e case of combustion with cupric oxide t h e high temperature would decompose t h e calcite, rupture t h e quartz grains a n d t h e carbon dioxide set free would be calculated as organic carbon, since i t would not appear in t h e ordinary carbonate determination. Examination of 2 8 samples of Hagerstown silt loam for calcite inclusions disclosed their presence in all samples b u t one. One of these, a sample from Chattooga County, Georgia, was selected as suitable for determining whether or not these theoretical considerations would be borne out in practice. A sub-sample ground t o pass a sieve 80 meshes t o t h e inch, well mixed a n d dried a t I O j O C., was used throughout, all results being stated as per cent of t h e dried soil. T h e following determinations were made: (11 Combustion with cupric oxide in a current of oxygen;
