An examination of this table shows that the differences in ash and sugar are negligible, but the following differences may be noted in water, oil, and protein by averaging the two seasons : HtO
% 3.67 4.59
Sacramento Paso Robles
PROTEIN
OIL
‘%
% 53.67 51.55
22.10 24.87
of Variety on Composition of California Almonds Hi0 ASH OIL PROTEIN SCGAR
% Nonpareil Ne Plus
I. x.L.
Drake Average
4.173 3 740 4.514 4 099 4.11
%
%
3 40 3.32 3.21 3.24 3.24
52.1 52.6 50 9 54.8 52.6
% 23.27 23.80 23.45 23.35 23.49
of Variety and Locality on Composition of California Almonds HzO ASH OIL PROTEIN SUGAR
Table VIII-Effect VARIETY
P A S 0 ROBLES
Nonpareil N e Plus I. x.L. Drake Average
% 4.63 4.43 4.79 4.53 4.59
% 3.14 3.29 3.42 3.35 3.30
%
%
%
52.23 51.92 48.27 51.71 51.03
23.28 24.93 24.50 26.86 24.89
5.74 5.29 6.02 4.69 5.43
52.10 53.18 53.09 55.73 53.52
24.22 24.27 24.03 22.21 23.68
5.58 5 . I4 5.10 5 07 6.22
SACRAMENTO
Thus, while lower in protein and moisture, the Sacramento almonds are high in oil. Though the trees in the Sacramento Valley are irrigated, the Paso Robles almonds had a higher moisture content, owing to storage conditions after harvesting. EFFECT OF VARIETY-A comparison of varieties is given in Table VII. Table VII-Effect VARIETY
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
Oct.ober, 1930
Nonpareil Ne Plus
I. x.L.
Drake Average
3.93 3.64 4.29 4.14 4.00
Locality apparently affected composition more than did variety. For example, the Drake from Sacramento was high in oil and low in protein while the opposite is true of the Drake from Paso Robles. The values for the ash and sugar content of the different varieties show no important deviation from the average.
% 5.31 5.19 5.27 4.84 5.12
There is even less variation according to variety than according to locality. The most noticeable deviation from the average is the value of 54.8 per cent for the oil in Drakes, which is somewhat higher than any of the other varieties. Moisture, ash, protein, and sugar are all very close to the average. Therefore, the season and locality differences are more important than varietal differences. I n Table VI11 the analyses averages of two seasons, of the four varieties, are separated into their respective localities.
3.25 3.26 3.07 3.10 3.17
Summary
1-The shearing stresses of almonds were found to substantiate the “tooth-test” in determining texture. %Differences in hemicellulose content did not explain differences in texture. 3-The average composition of the nuts from the two leading almond districts was practically identical, with the single exception that the Drakes were slightly higher in oil. 4-The Drake from Sacramento gave the highest average oil content. Literature Cited (1) Dore, University of California, Syllabus, Plant Nutrition 101.
Isolation of the Humic Acids‘ Gilbert Thiessenl and Carl J. Engelder UNIVERSITY OF PITTSBUROH, PITTSBURGR, PA.
In order that the chemical nature of coal may be better understood, there is need for a better understanding of the nature of the humic acids. The present nomenclature and methods of preparing the humic acids leave much to be desired, for we know very little about these very complex colloidal plant decomposition
materials. The authors have presented a method of extraction and purification of the humic acids which has yielded good results. The analyses and molecular weights of some of the humic material studied are presented. The absorption spectra of some of the humic acids in the region of visible light have been determined.
...... . . . . . . .
I
N THE study of the chemical constitution of coal the study of coal in itself has not proved satisfactory. The coal should be separated into its indiddual components and these components made the subject of separate investigations. The botanical composition of coal has been very successfully determined by studying peat and then noting the changes the various plant components undergo as the rank of the coal increases. Similarly, the same procedure should prove of value in the determination of the chemical nature of coal, since the constituents of peat are more reactive and easier to handle than those of coal. Humic acids have probably been the subject of more investigations than any of the other constituents of peat and coal. These are the dark brown, colloidal, alkali-soluble materials which have been formed, according to the most widely accepted theories, by the natural decomposition of lignocellulose. They are very complex substances whose 1 Received
May 22, 1930.
* Contribution No. 192 from the Department of Chemistry, University of Pittsburgh. Submitted in partial fulfilment of requirements for the Ph.D. degree b y G. Thiessen.
chemistry is intimately bound up with the chemistry of coal, but about which very little is definitely known. A review of the literature relating to humic acids showed much to be desired in the methods of extracting and purifying these substances. The usual method employed in preparing humic acids for experimental purposes has been t o extract them from peat, brown coal, or oxidized bituminous coal. These sources of humic acids are more or less complex mixtures to start with and vary with the locality from which they are obtained. Furthermore, frequently no account is taken of the fact that alkali solutions, besides extracting the humic acids, also dissolve some resins, lignin, and organic acids. These impurities may profoundly influence the properties of the humic acids with which they are associated. The attempt was made to devise a satisfactory method for the extraction and purification of humic acids. As a starting material it seemed logical to use a piece of wood which had decayed under the conditions prevailing in a peat bog, instead of the heterogeneous peat. The species of wood should be known and should be a common constituent of peat bogs.
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I N D U S T R I A L A N D ENGINEERING CHEMISTRY Table I-Analyses MATERIAL
Decayed wood m'ood after extraction with acetone Acetone extract W o o d after extraction with acetone, C101, and NaOH Humic acid Hymdtomelanic acid
of Materials a t Various S t a g e s of Extraction
-1
ORIGISALANALYSES
H
C
0
N
S
ASH
%
%
70
70
%
%
56.8 57.2 65.7 60.0 56.4 57.8
5.4 5.7 6.8 5.5 4.9 4.9
36.2 35.5 26.7 33.0 34.7 35.2
0.1 0.1 0.3 0.0 0.2 0.2
0.2 0 2 0.1 0.1 0.3 0.3
1.3 1.3 0.4 1.4 2.5 1.3
Scheme of Extraction
A decayed log of white cedar, Thuja occidenlalis, from Hawk Island Swamp, Manitowac County, Wis., was chosen as the starting material for this study. Material from this swamp has been the subject of other investigators ( 4 ) in the laboratories of the United States Bureau of Milles. The log was broken up into small pieces, air-dried, and ground to pass a 12-mesh screen. During the course of the grinding the less decayed material, because of its greater toughness than the friable thoroughly decayed matter, was removed. The
Acid Extraction Flow Diagram
resinous materials were extracted with hot acetone. After extraction was complete, the residual acetone was removed from the extracted mass by evaporation under vacuum over a water bath. The acetone extract was decided!y resinous The lignin was nest removed by extraction with an aqueous chlorine dioxide solution, prepared according to the method of Schmidt (3) by saturating cold water with the gaseous products of the reaction of potassium chlorate, oxalic acid, and dilute sulfuric acid. I n carrying out the extraction 400 grams of the acetone-treated mass were placed in about 4 liters of the chlorine dioxide solution and allowed to stand about 24 hours. The liquid was decanted off and the extraction repeated twice more in the same manner. After the third extraction the washed residue gave no test for lignin
1
ASH-, N-,
AND
S-FREEBASIS H
C % 57.7 58.1 66.2 60.9 58.8 59.0
0
%
%
5.5 5.8 6.9 5.6 5.1 5.0
36:8 30.1 26.9 33.5 36.1 36.0
with phloroglucinol and hydrochloric acid. This test is carried out by placing R crystal of phloroglucinol with a small amount of the material to be tested which has been acidified with hydrochloric acid; a reddish coloration of the inatrrial is a positive test for the presence of lignin. The residuc mas well washed with distilled water and was then ready for the extraction of the humic acids with sodium hydroxide. The use of ammonium hydroxide is apparently not advisable for the extraction in view of the investigations of Fuchs and Leopold (2) which show that ammonia is very strongly adsorbed by humic acids and possibly may also introduce amino groups into the humic acid molecule. It is also unpleasant to work with large quantities of strong ammonia solutions. Sufficient 4 per cent sodiiim hydroxide solution to form a fairly liquid mass wa9 added to the residue from the previous extraction and allowed to stand, with occasional stirring, for several hours. Upon addition of the caustic soda solution to the previously almost granular decayed wood residue, the mass became very slimy and absorbed most of the solution. It was very difficult to remove the sodium humate solution from this mixture by filtration. Separation was most easilv accomplished with a small DeLaval oilpurifying centri"fuge. A rough separation was first made 2'4
Figure 1-Humic
Vol. 22, No. 10
3
Wave lengfh in Cm. x IO6 1-Humic acid from brown coal, 1.08 grams per liter in dilute "4OH 2-Humic acid from desized wood, 1.08 grams per liter in dilute "4OH 3-Brominated humic acid, 1.7 grams per liter in acetone 4-Nitrated humic acid in acetone Figure 2
by rapidly running the material through the centrifuge. The humate solution was then clarified by running i t slowly through the centrifuge several times. The humic acids were precipitated from the clarified solution by the addition of hydrochloric acid and removed from suspension by centrifuging. They were washed by being dispersed in distilled water and reprecipitated by centrifuging. Washing w m continued by repeatedly dispersing the humic acids in water and recovering them by centrifuging, until the final wash
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
October,’ 1930
water showed only slight amounts of chlorides. As washing proceeded and the electrolytes were removed, the humic acids showed greater and greater tendency t o form very fine colloidal dispersions, from which they were removed only with difficulty. The washed humic acids were dried at 30” C. in v(zcuo, first over sulfuric acid and finally over phosphorus pentoxide. A portion of these acids should be soluble in ethyl alcohol. The alcohol-soluble fraction has been given the name “hymatomelanic acid” by Hoppe-Seyler. The alcoholinsoluble fraction has been considered to be the true humic acid. This separation was made using hot absolute ethyl alcohol and evaporating the alcohol from both the extract and the insoluble residue under vacuum. The scheme of separation which was followed is presented diagrammatically in Figure 1. Analyses Samples of the materials were taken at various stages and analyzed. These figures were then recalculated to an ash, nitrogen, and sulfur free basis. Both sets of analyses me given in Table I. The two humic acids are very similar in elemental composition. This would lend weight to the theory that they are the same material, differing in their solubilities because of differing colloidal particle size. The molecular weights of the humic acids theniselves are difficult to determine, since they are not soluble in any of the solvents used for molecular weight determinations. A portion of the alcohol-soluble material was soluhle in acetone and its apparent molecular weight could therefore be determined. Fuchs (1) has prepared the nitro and bromo derivatives of the humic acids. These materials are easy to prepare and are soluble in acetone. It may be that the humic acid complex is broken down during the treatment. The apparent average molecular weights of several of the materials studied are presented in Table 11. Absorption Spectra All humic acids are colored. This fact has been written into most of the definitions of humic substances which have been put forward. It was thought to be of interest to deter-
1133
mine whether the absorption spectra of the various materials studied were the same or similar. Table 11-Approximate Molecular Weights of Humic Acids Acetone-soluble humic acid 800 Nitro humic acids 1040 Bromo-humic arids 940 Nofe-These values were obtained by the method of McCoy, using between 0.4 and 0.0 gram of matenal In about 20 ml. of acetone. Similar values were also obtained by the microchemical method of Pregl. The individual values from which the average for the nitro humic acids was derived were 988. 990. 10-30,1050,and 1150. These mo!ecular-weight values are of about the same magnitude as those found in the literature.
The absorption measurements were made with a HilgerNutting photometer and a Hilger constant-deviation wavelength spectroscope. The curves obtained by plotting the data were all of approximately the same shape. The m a t e rials in solution were almost completely transparent to red and yellow light and became less and less transparent to light of decreasing wave length, being practically opaque to blue and violet light. Figure 2 shows some typical curves obtained. An absorption spectrum curve for a humic acid obtained from brown coal is included for comparison. It was found that the brominated and nitrated acids were less highly colored, as were also the more soluble fractions. The authors did not notice the black almost always said to be characteristic of humic acids, when the materials were carefully prepared. Instead, they weqe all of various shades of brown. The absorption spectra of humic materials in the ultraviolet region of the spectrum would probably be more interesting than those in the visible region. Lignin shows some very interesting properties in this region. Acknowledgment The authors wish to express their appreciation to G. St. J. Perrott for permission to use the facilities of the Pittsburgh Experiment Station of the United States Bureau of Mines, and to Reinhardt Thiessen for his help and suggestions during the course of the work. Literature Cited ( 1 ) Fuchs, Bicnnstof-Chcm.,B, 175 (1938). (2) Fuchs and Leopold, I b i d . , 8, 73 (1927). (3) Schmidt, B n . , S4,1860,3241(1921);66, 1438 (1923); 17,1834 (1924). (4) Thiessen and Johnson, IND. END.CHEM..Anal Ed., 1, 216 (1929).
Action of Rotenone upon Mammals When Taken b y Mouth-Preliminary Report’ D. E. Buckingham 3108 H.AWTHORNE PLACE, WASHINGTON, D. C.
OTENOKE is the principal insecticidal constituent of Dvrris elliptica, of the South American plant ‘‘cube” (Lonchcarpus nicou), and of certain other tropical fish poisoning plants. It is a white crystalline compound having the formula C23H2206. It is insoluble in water, but soluble in acetone, chloroform, and many other organic aolvents. Rotenone is extremely toxic to fish, 1 part in 20,000,000 parts water killing goldfish in 3 hours; and it is also highly toxic to insects. It is effective both as a contact and as a stomach insecticide. Derris extract has been used as an ingredient of an arrow poison by the Borneo bead hunters. According to Newbold ( d ) , a tiger died within 3 hours of being wounded with three arrows tipped with this mixture. This toxic action may have been due to constituents in the arrow poison other than those from derris. Campbell (1) made tests with derris upon vari-
R
1
Received August 26, 1930.
ous animals and reported that the sap from only 2 grams of the root when administered by mouth is sufficient to kill a monkey. The usefulness of rotenone as a n insecticide would be Reriously curtailed if i t were markedly toxic to warm blooded animals, if for instance its action were similar to that of strychnine, curare, or similar drugs. The ideal agricultural insecticide is one that is toxic to insects but harmless to man and domestic animals eating fruits, vegetables, or grass that has been sprayed or dusted. The object of the investigation here reported has been to determine what action rotenone, when taken by mouth, has upon farm animals, such as cows, horses, pigs, sheep, goats, and chickens, as well as upon household pets, such as cats, dogs, and canary birds. I n thefie tests the rotenone was administered mainly by mouth, as only in that way do domestic animals normally come into contact with insecticides that have been applied to vegeta-
