8$0
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
be seen t h a t there is a decrease of 86 per cent as a result of sulfuring, while the completion of the clarification process renders the juice practically sterile. However, when the massecuite is exposed t o the air, and especially when i t enters the centrifugal, reinfection takes place. The rapidly whirling centrifugal sucks air from below a t great speed and any organisms on the floor or in the mill a t large have an opportunity of gaining an entrance. This is corroborated by the fact t h a t the air below the centrifugal has approximately three times the number of molds t o be found in the air above the centrifugal. It might be well t o keep the centrifugals covered as well as the mixer which brings the massecuite t o t h a t point. The bacterial counts follow the same general trend as the molds. Blue Aspergillus and Cladosporium were the predominating molds appearing under the local conditions. These were likewise found in two of the largest factories in Louisiana. The fact t h a t the Blue Aspergillas is so universal in its habitat and so strong in its deteriorative power makes it advisable to develop methods for its elimination along with the other molds. SUMMARY
I-The molds appearing with the greatest frequency in manufactured cane sugars of different grades belong chiefly t o the Aspergilli and Penicillia. 2-The organism which appeared with the greatest frequency from all sugars, the Blue Aspergillus) also had the greatest deteriorative power. 3-Sterilized sugars inoculated with pure cultures of molds deteriorated rapidly where the moisture content was appreciable. Little, if any, deterioration occurred when the moisture content was reduced t o a minimum. 4-Sugars ordinarily guaranteed against deterioration by virtue of the factor of safety rule are capable of undergoing deterioration if sufficiently infected with molds. 5-Molds cause an inversion of sucrose where only spores are present, as well as when mycelia are developed. It would appear, therefore, t h a t some mold spores, as such, contain invertase. ACKNOWLEDGMENT
The authors are appreciative of the assistance they have so generously received from Dr. C. A. Browne, Mr. W. L. Owen, Dr. Charles Thom, Assistant Director W. G. Taggert, Dr. F. Zerban, and Mr. E. C. Freetand. DEPARTMENT OF BACTERIOLOGY LOUISIANA SUGAR EXPERIMENT STATION NEWORLEANS, LA.
AMERICAN TOMATO SEED OIL1 By GEORGE s. JAMIESONAND H. s. BAILEY Received March 1 , 1919
The object of this investigation was t o prepare a number of samples of oil from tomato seed grown in various localities in the United States and determine the so-called constants for each sample of oil. Also it was proposed to make a study of the chemical composition of tomato seed oil in order to determine if it 1
Published by permission of the Secretary of Agriculture.
Vol.
11,
No. g
contained any constituents in addition to those already known. I n 1914, a brief report of the work which had been accomplished was made by Bailey and Burnett,l on the extraction and refining of tomato seed oil. It was shown a t t h a t time that the crude oil could be readily refined by the well-known alkali process and t h a t by a subsequent treatment with fuller’s earth, a very pale yellow oil was produced which appeared suitable for use as a salad oil. Since the abovementioned report was made several more samples of oil have been obtained and studied. While making a preliminary investigation of the chemical composition of the oil i t was found t h a t the Renard test indicated the presence of a considerable amount of arachidic acid. However, i t will be shown that tomato seed oil actually contains a very small amount of arachidic acid. The Renard test was repeated several times but in each case the same result was obtained, although great care was taken t o follow the directions given for this test in every detail. These results show t h a t the Renard test when applied t o unfamiliar oils cannot be relied upon t o indicate the quantity of arachidic acid present. I t is hoped t h a t this important observation will be properly emphasized in the future editions of books on oil analysis. Several attempts were made a t various times t o separate the arachidic acid by fractional crystallization from 90 per cent alcohol, of the fatty acids obtained by the Renard test, but without success. Then i t was decided t o make a n exhaustive study in order t o determine if any arachidic acid was present in tomato seed oil, with the result t h a t the completion and publication of these investigations were much delayed. Meanwhile a study on “The Utilization of Waste Tomato Seeds and Skins” was made by Rabak, of the Bureau of Plant Industry, the results of which were published in bulletin form in 1 9 1 7 . ~ This bulletin gives statistics on the amount of tomato seeds and skins, as well as the quantity of oil and press cake produced in Italy, and also indicates the amount of this waste product available in the United States. Since the bulletin gives a satisfactory description of the modern pressure and solvent methods for obtaining the oil on a commercial scale, i t will not be necessary t o discuss them here. The chemical investigation of the tomato seed oil extracted by solvents described in the above-mentioned bulletin showed t h a t it contained 17.54 per cent of solid acids and 75.84 per cent of liquid acids. It was also shown t h a t the oil had the following approximate composition: Per cent 45.00 .............. .............. 34.20
Olein. Linolein
Per cent Palmitin.. ............ 12.47 Stearin ............. 5.89
The remaining small portion consisted of free acids and unsaponifiable matter. I n addition t o these compounds Battaglio3 has shown that tomato seed oil contains a small amount of myristin. A further attempt was made on much larger scale than in the first experiments t o separate the arachidic acid from the palmitic and stearic acids by fractional crystallization. About 36 g. of the solid fatty acids 1 2
3
Science, 39 (1914), 953. U. S. Dept. of Agr., Bull. 63% (Professional Paper). Les Corps gras., 1901, 135
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 N N G C H E M I S T R Y
Sept., 1919
SAMPLE NUMBER
1 0,9191 1.472 121.5 187.5
................ number ................. .... 1 number.. ............. Polenske number. .................... .... Acetyl value.. ....................... 18.5 Insoluble fatty acids per cent.. ........ 95.8 0.5 Soluble fatty acids i e r cent.. .......... Unsaturated (liquih) acids, per cent. .... 77.0 Saturated (solid) acids, per cent.. ...... 16.0 nus)
1
21 0.9196 1.4722 117.5 187.0
.... ....
11.5 96.6 0.7 77.0 15.0
3 1, 0.9189 1 .4722 122.5 187.0
....
11.4 95.5 0.5 79.0 16.0
Expressed oil from V. D. Anderson Company. 1 refined with sodium hydroxide, sp. gr. 1.1.
* Sample 3 is Sample
were obtained from the tomato seed oil by the lead salt-ether method. This mixture of fatty acids was found t o melt at 5 5 ' ) while the acids obtained previously by the Renard test melted a t about 58' C. After 6 crystallizations from go per cent alcohol the melting point was 69' C. and i t was not raised by three recrystallizations, which clearly indicated t h a t i t was not possible t o separate a small amount of arachidic acid from large amounts of palmitic and stearic acids. However, this fractional crystallization did effect the separation of some of the stearic acid free from palmitic as shown by the fractions which melted a t 69' C. There are several possibilities by which the arachidic acid may have been lost. One is that on account of the small amount of acid present i t was either held in solution by the solvent action of the other acids or even by the alcohol itself, while another possibility is that the arachidic acid was converted into its ethyl ester, which is much more soluble in alcoho: than the free acid.' Precautions were taken during the solution of the acids in alcohol not t o heat any longer or hotter than necessary t o completely dissolve them. However, i t was found t h a t arachidic acid could be obtained by fractional distillation of the methyl esters of the solid fatty acids under diminished pressure. The esters were prepared by heating 47 g. of the solid acids which were obtained from 300 g. of tomato seed oil by the lead salt-ether method, with 2 0 g. of pure methyl alcohol and 2 0 0 cc. of absolute ether for 1 5 hrs. in the presence of 2 5 per cent of anhydrous hydrochloric acid2 When the solution had cooled almost to room temperature, 400 cc. of ether were added and the contents of the flask were transferred t o a separatory funnel. The ether solution was washed twice with 300 cc. portions of water in order to remove the uncombined methyl alcohol and most of the hydrochloric: acid. Then the ether solution was thoroughly agitated with another 300 cc. of water containing 5 g. of sodium bicarbonate which removed the remaining hydrochloric acid and any free fatty acids. After washing once more with water, the ether solution was dried over calcium chloride for about 1 5 min. and the ether was removed by distillation. The methyl esters were then distilled under diminished pressure in t h e following manner: After the completion of the first distillation in which I 2 fractions were collected, each fraction in turn was added t o the distilling bulb as its former boiling point was reached and redistilled in order to secure as complete a separation as possible of the esters. In like manner the fractionation was 1 2
Lewkowitsch, 5th Ed., 1, 166 I b X , p. 665.
4s 0.9186 1.4723 122.6 186.3
.... ....
10.0 95.4. u.44 80.6 14.7 8 4
5 0.9189 1.4720 122.0 192.0 0.1
0.6
13.1 96.0
....
77.0 17.0
6 0.9189 1.4728 125.0 192.0 0.3 0.6 14.1 95.5
....
77.0 16.7
7 0,9190 1.4725 125.0 192.0 0.3
0.9184 1.4725 122.5 192.0 0.3
.... .... 77.6
12.8 95.7
79.0 15.5
17.2
....
9
8
0.6 12.3 96.0
851
....
1.4725 125.0 191.0 0.3 0.4 17.6 96.1
....
76.1 18.0
104 ._
....
1.4715 122.0 188.2
.... ....
20.5 95.0
....
80.2 15.0
This sample is Sample 3 bleached with fuller's earth. Oil extracted from tomato seed with petroleum ether.
repeated 5 times. Since these distillations were made primarily t o separate the arachidic ester from the other esters, only the last three of the final 1 2 fractions obtained are given in the following table. FRACTION NUMBBR 10 Boiling point, deg. C .............. 170-173 3.0 Pressure, m m . . . . . . . . . . . . . . . . . . . . 1.7 Weight of fraction, grams. 31.0 Melting points, deg. C.. 69.0 Melting points of acids, deg. C...
........ .......... ..
11 173-180 3.0 0.6 35.0 77.0
12 18C-220 3.0 1 .o 40.0 77.0
When Fraction 1 2 was crystallized once from go per cent alcohol, the melting point was raised t o s o o C. I n order to get the free acids the esters were saponified with alkali and the fatty acids were precipitated by adding an excess of hydrochloric acid. The acids were filtered off, washed with cold water, and purified by crystallization from go per cent alcohol before taking the melting points. From Fractions 11 and 1 2 , 1.2 g. of acid melting a t 7 7 ' C. were obtained: Assuming this t o be pure arachidic acid, it would indicate t h a t the original oil contained a t least 0.4 per cent of this acid. Recently the methyl esters were again prepared from about 5 0 g. of the solid fatty acids and distilled. I n this experiment the redistillation of the fractions was repeated only twice. The portion boiling between 190' C. and 197O C. a t 6 mm. pressure was recrystallized from 95 per cent alcohol five times. The purified ester melted a t 54' C. When this ester was mixed intimately with an equal amount of methyl arachidate which had been prepared from pure arachidic acid, the melting point was not changed. This proved definitely t h a t the ester obtained by the distillation of the methyl esters of the solid fatty acids from tomato seed oil was methyl arachidic. One of the objects of the investigation as mentioned above was t o obtain the oil from a number of different samples of tomato seed in order t o get more data upon the so-called constants of the American tomato seed oils and also t o ascertain if there was much variation in the composition of these various oils. The table a t the top of this page gives the physical and chemical constants of oils obtained from different samples of tomato seed. I t should be observed t h a t Samples I, 2, 5 , 6, 7, and g were pressed from the air-dried seed in the continuous type of press known as an expellor. The oil obtained by the expellor is light red in color and has a spicy taste resembling paprika. Also it will be observed t h a t the refining of the oil with alkali and the bleaching with fuller's earth has not appreciably changed any of the constants of the oil except that of the acetyl value. With the exception of Sample 2, the air-dried to-
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 mato seed gave a yield of about z j per cent of oil when extracted with ether and about 18 per cent of oil when the expeller was used. I n this connection i t might be of interest t o note t h a t the yield of oil obtained in Italy by pressing’the tomato seed is about 18per cent. SUNMARY
The constants have been determined for nine different authentic samples of tomato seed oil. It has been shown t h a t tomato seed oil contains a small amount of arachidic acid. BUREAUOF CHEMISTRY DEPARTMENT OF AGRICULTURS WASHINGTON, D. C.
AN ELECTROLYTIC RESISTANCE METHOD FOR DETERMINING CARBON IN STEEL1 By J. R. CAIN AND L. C. MAXWELL Received June 18, 1919
INTRODUCTION
The purpose of this study was t o investigate the accuracy, speed, and practicability of a method for determining carbon in steel, dependent in principle on passing the carbon dioxide produced by direct combustion. of the metal into a solution of barium hydroxide of known electrical resistance; after complete absorption of this gas the resistance is again determined and from the increase in this (due t o precipitation of barium ions) the percentage of carbon is deduced. This method is new in principle and i t is believed t h a t the principle can be applied generally in many cases where the substance being determined precipitates another substance from solution with resultant change in resistance. The assembly of apparatus for determining resistance is also new,2 and offers many advantages for technical work over the methods hitherto in general use for measurement of electrolytic resistances, which require the use of induction coils or high frequency generators, tuned telephones, balanced inductances and capacities, etc. Other new features are the application of the nomograph8 for the graphical representation of resistance data and the use of special conductivity cells with adjustable electrodes t o facilitate the manufacture of any number of such cells with the same cell constant. Much work has been done by others on electrochemical analytical methods. I n general, these fall into three groups in which an end-point is shown electrochemically by the following methods: ( I ) The unknown concentration is obtained from curves expressing a relation between cubic centimeters of titra1 Complete equipment for determination of carbon by this method may be obtained from Arthur H. Thomas Co., Philadelphia. 2 The elements of this were described by Weibel and Thuras. THIS 10 (1918), 626. JOURNAL, a The mathematical work in constructing the nomograph shown in Fig. 4 was done by Mr. H . M. Roeser of this Bureau at the request of the senior author, who suggested its application to electrolytic resistance data. A paper on this subject is in preparation by Mr. Roeser. References on the nomograph are: “Trait4 de Nomographie,” by M. d’Ocagne, GauthiersVillars, Paris; “Graphical Methods,” by Carl Runge, Columbia University Press, New York; “Graphical Interpolation of Tabulated Data,” by H. G. Deming, J . Am. Chem. Soc., 89 (1917), 2388; “The Nomon, a Calculating Device for Chemists,” by H. G . Deming, I b i d . , 89 (1917), 2137.
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ting solution and conductivity (or a related quantity) of the solution titrated;‘ ( 2 ) the unknown is obtained from curves giving the relation between cubic centimeters of titrating solution added and the corresponding electromotive forces of a cell composed of a normal electrode and an electrode not acted upon by the solution being titrated, the latter being the electrolyte;2 (3) special application of Method z used for determining hydrogen ion in acidimetry and alkalimetry and in precipitations from neutralized solutions.8 Such methods suffer by comparison with the present for the following reasons: ( I ) A curve has t o be plotted for every determination, which consumes much time; ( 2 ) the apparatus required t o determine carbon with a n accuracy of 0.01 per cent carbon would be too delicate and inconvenient of manipulation for every-day use; (3) the difficulty in some cases of fixing with sufficient definiteness the inflection or break in the curve denoting the end-point of the titration. Upon further comparing these methods with the present, i t is seen t h a t the latter dispenses with one operation common t o all the others, namely, the addition of successive portions of a titrating solution and the determination of the resistance a t each addition, resulting in additional time-saving. From an inspection of the chemical equation for the reaction underlying the present method, ’ Ba(OH)2 COZ = BaC03 HzO, i t is evident (when any given conductivity cell is used) t h a t the only factors which act t o change the conductivity of the barium hydroxide used for absorption are ( I ) the amount of carbon dioxide absorbed, which determines the disappearance from solution of the barium ion, and ( 2 ) the temperature. Since carbon dioxide precipitates barium without leaving reaction products in the solution t o increase the conductivity (such as would remain if, for instance, sodium sulfate were the precipitating agent for the barium) i t can be seen t h a t the present method should give the maximum possible change of resistance €or a given amount of barium removed-a condition tending to secure a high degree of sensitiveness.* However, the temperature coefficients of resistance of barium hydroxide solutions in the range of concentrations herein employed (Fig. 2) average nearly 1 . 7 per cent per degree, hence i t is evident t h a t the accuracy of t h e method will be largely affected by temperature if due correction is not made. I n developing this method it was deemed necessary: (I) To construct the curve showing resistance as a function of concentration of barium hydroxide solutions ranging from very concentrated t o very dilute and t o select the portion of this curve showing the maximum change of resistance for a given change of
+
+
1 Harned, J . A m . Chem. SOC., 89 (1916), 252; Findlay, “Practical Physical Chemistry;” Ostwald-Luther, “Physikalisch-Chemische Massungen.” 2 Loomis and Acree, Am. Chem. J., 46 (1911), 585, 621 (a bibliography is also given); Hildebrand, J . A m . Chem. Soc., 8 1 (1913), 869; Kelly, I b i d . , 88 (1916), 341. a Hildebrand, LOC.cit. See also Weibel and Thuras, THIS JOURNAL, 10 (1918), 626, for another electrolytic method. 4 Compare the conditions in Harned’s work with Ba(0H)z solutions.
LOC.
cit.
