INDUSTRIAL AND ENGINEERING CHEMISTRY
336 Results
Malic and citric acids were found in all samples examined. Formic acid, formerly assumed to be an important acid in honey, is present in a relatively small amount, confirming the observations of Fincke (4), Heiduschka (6), Farnsteiner (s), and others. The results obtained are given in Tables I and 11. Examination of Tulip Honey I n the examination of tulip honey, 4 kg. were diluted with water and alcohol and precipitated with 100 grams of lead subacetate. The precipitate was filtered and washed. Carbon dioxide was passed through a water suspension of the precipitate, and it was then filtered and washed again, The acids recovered from this precipitate were extracted with ether, yielding a crystalline acid which, after recrystallization, was identified by the melting point and optical crystallographic data as succinic acid. The residual acids were converted into ethyl esters, yielding 6 grams of the mixed esters. This mixture, fractionated a t 10 mm., afforded 0.2 gram boiling a t 80-125" C., 0.33 gram boiling a t 125-140" C., 0.7 gram boiling a t 140-160" C., 0.52 gram boiling at 160-170° C., and 2.4 grams boiling a t 170" C. Levulinic acid was identified in the lowest fraction by means of its hydrazide. This undoubtedly resulted from the action of the alcoholic hydrochloric acid during esterification on sugars occluded by the lead precipitate. Malic acid was found in the second, third, and fourth fractions by means of its hydrazide, melting at 178-179" C., while the fifth and largest fraction yielded citric hydrazide, melting at 103-105" C. and further identified by optical crystallographic data. A separate extraction with ether of 200 grams of the honey, acidified with hydrochloric acid, yielded 0.024 gram of purified succinic acid, equivalent to 0.012 per cent. The predominating non-volatile acid of tulip honey, therefore, is citric acid (about 0.04 per cent). It also has about 0.012 per cent of succinic acid, and a smaller amount of malic acid.
~'01.23, SO.
3
Table I-Volatile Acids of H o n e y FORMIC ACETIC FORMICCOM- ACETIC Cox- FORMIC ACETIC SOURCE FREE BINED FREE BINED TOTALTOTAL
VARIETY
%
%
%
%
Tulip Md. 0.007 0.017 0,009 Mesquite Calif. 0.003 0.004 0.002 Sage Calif. 0.004 0.001 0.039 Orange Calif. 0.004 0.002 0.003 Sourwood Va. 0.007 0.004 0.002 Spanish needle Ill. 0.010 0.012 0.005 Alfalfa Utah Nil 0.001 0.007 Clover Ohio 0.004 0.002 0.002 Star thistle Calif. 0.004 0.003 0.003 Cotton Tex. 0.006 0.005 0.006 Sweet clover Colo. 0,002 0.006 0.003 Fireweed Wash. 0.006 0.003 0.007 Alfalfa Calif. 0.007 0.003 0.004 White clover" Ohio 0,007 0.005 0.002 Algarroha Hawaii 0.002 0.009 0.004 This honey has a green color. The producer honey or other honey may be mixed with it.
Y
o
%
.-
0.007 0.024 0.016 0.003 0.007 0.005 0.007 0.005 0.046 0,002 0.006 0.005 0.008 0.011 0.010 0.004 0.022 0,009 0.005 0.001 0.012 0.004 0.006 0.006 0.002 0.007 0.005 0.006 0.010 0.012 0.003 0.008 0.006 0.006 0.009 0.013 0.003 0.010 0.007 0.005 0.012 0.007 0.010 0.011 0.014 states that sweet clover
Acids of H o n e y ALKALINFREE ITY OF MALIC CITRICS ~ C C I N I C VARIETY SOURCE ASH ACIDITY ASH ACID ACID ACID 70 Cc./lOO nramsa % % Sourwood Va. 0.28 23.0 -30.0 0.003 0,006 Present Spanish needle Ill. 0.18 17.3 22.0 Trace 0,001 Alfalfa Wash. 0.06 13.5 6.3 Trace 0,001 Trace (?) Clover Ohio 0.05 13.0 5.3 Trace 0.001 Star thistle Calif. 0.09 23.0 7.5 Trace Trace Cotton Tex. 0.34 22.5 42.0 0.056 0.008 Present Sweet clover Colo. 0.04 10.0 4.3 Trace 0,001 Fireweed Wash. 0.07 9.5 8.0 Trace 0,001 Alfalfa Calif. 0.17 27.5 20.5 0.002 0.002 White clover Ohio 0.11 19.5 13.5 Trace 0.001 Algarroba Hawaii 0.52 13.5 37.0 Trace 0.001 Mesquite Calif. 0.15 14.0 20.0 0.011 0.007 Orange Calif. 0.06 14.0 7.5 Trace 0.001 Calif. Sage 0.06 11.5 6.5 Trace 0,001 a Expresse d in terms of 0.10 ' .V solutions. Table 11-Non-Volatile
Literature Cited (1) Assocn. Official Agr. Chem., 1925, p. 213. (2) Dyer, J . B i d . Chem., 28, 452 (1917); Table V. (3) Farnsteiner, 2. Nahr. Genussm.,113, 598 (1908). (4) Fincke, I b i d . , 23, 255 (1912). (5) Hartmann and Hillig, J. A m . Assocn. OBicial Agr. Chem., 13, 99 (1930). (6) Heiduschka, 2. Nahr. Genussm., 21, 375 (1911). (7) Heiduschka, Pharm. Zentralhalle, 62, 1051 (1911); Schzueiz. Wochschr., 49, 725 (1911). (8) Utz, Pharm. Post, 4 1 (6-7), 69 (1908).
Increasing the Purity of Common Salt' Thos. B. Brighton and Carl M. Dice DEPARTMENT OB
- ? I N I N G AND
hfETALLVRGlCAL RESEARCH,UNIVERSITY
F THE approximately 7.5 million tons of salt produced
0
each year in the United States, about 30 per cent is obtained from the evaporation of brines, either natural or artificial. Solar evaporation makes up only a small portion of this and is confined to the more arid parts of the country, especially to the vicinity of the Great Salt Lake in Utah and to parts of California. The brines from the Great Salt Lake contain as a rule somewhat over 20 per cent of solids, and of this approximately three-quarters is sodium chloride. The other constituents might empirically be said to be chiefly sodium sulfate, magnesium chloride, and potassium chloride. This natural, nearly saturated brine, available in unlimited quantities, makes an excellent raw material for the production of high grades of salt. Manufacture of Salt from Great Salt Lake Brine The water from the lake is first pumped to settling ponds, each covering about 250 acres. Here it is allowed to remain 1
Received December 15, 1930.
OF
UTAH.
AND
u.
s
BUREAUO F MINES,SALT LAKE CITY, UTAH
until, owing to solar evaporation, it is practically completely saturated. The brine then flows by gravity to smaller crystallizing ponds, each 10 acres in area. Flow through these ponds is continuous throughout the evaporating season and is so regulated that only sodium chloride crystallizes from the solution. Other salts are not present to the saturation point in the outflowing bitterns and so are removed. Care must be used, however, in the autumn as the nights become cool, to see that the ponds are drained before sodium sulfate crystals form. At this time of year the brines are near saturation with Glauber's salt even a t daytime temperatures. Hence the salt harvest begins usually in early September. In the bottom of each crystallizing pond is a floor of salt 12 to 15 inches thick. This is maintained and kept clean by the rapid and complete evaporation of a small amount of brine a t the beginning of the evaporation season. On top of this floor the salt crystals form during the summer to the depth of 3 to 5 inches. At the end of the evaporating season the bitterns are drawn off and the salt is allowed to drain. The salt layer is broken up by tractor-driven plows down
INDUSTRIAL A N D ENGINEERING CHEMISTRY
March, 1931
to the "split" or top of the permanent floor. Then by means of tractor-drawn scrapers and belt elevators the salt is collected from the ponds and piled ready for sending to the refinery. After the harvest and before the next evaporating season rain and snow water dissolve any impurities that crystallize during cold weather and, when drawn off, leave the ponds clean and ready for the laying down of the new floor. The piled salt is somewhat contaminated by impurities in the mother liquor, but a considerable part of these are washed off by the fall and spring rains. The undesirable salts that are left are later removed in the refinery. From the stock piles the salt is hauled to the mill on standard railroad cars. It is unloaded into a bin and by means of a belt conveyor and bucket elevator is fed into an oilfired rotary kiln for drying. The oil flames do not enter the kiln, the salt being heated by the hot gases from the Carborundum-lined furnace into which the flames are projected. The salt leaves the kiln a t 300" F. (150" C.) and is pure white, though rather dull owing to adhering fine powder. The principal impurity on the crude salt crystals is Glauber's salt, Na2SO4.10H20. This is dehydrated during the drying and most of it is blown off by the blast through the drier. From the drier the salt goes to a rotary cooler, from which it emerges at a temperature safe for handling on wood. Further treatment consists of repeated crushing and screening to produce products known as hay salt, stock salt, ice-cream salt, special stock, number one salt, number two salt, cattle block salt, table salt, dairy salt, etc. The various grades and sizes are packed in bags, barrels, cartons, etc., to suit the convenience and needs of the stock men, packers, canning factories, butter makers, housewives, and other users. Composition of Salt *%.:sampleof salt direct from the ponds had the following composition, calculating all calcium as sulfate and the rest of the SO4 as sodium sulfate: %
Water-insoluble. . . . . . . . . . . . . . . . . . . 0.04 CaSO4.. . . . . . . . . . . . . . . . . . . . . . . . . . 0.41 3.78 NaBOI., . . . . . . . . . . . . . . . . . . . . . . . MgC12.. . . . . . . . . . . . . . . . . . . . . . 1.91 NaCl (by difference), . . . . . . . . . . . . . . 93.86
Acthe salt passes through the refinery the purity of each succeeding product is increased, as shown by the following analyses, calculated as above. As noted, most of the impurity present is calcium sulfate.
Odor Tests When local solar salt or most brands of eastern salt is dissolved in boiling water, an unpleasant musty odor is noticeable and, if considerable salt is used, a perceptible amount of scum forms on the surface of the solution. This odor is somewhat like that noted when ordinary U. S. P. Epsom salt is dissolved in hot water, though very much less intense. It was assumed that the local salt is not used for butter making because of this odor and scum, and so experiments were carried out whose purpose it was to eradicate the trouble. Odor tests were made on all grades of salt made from the brines of the Great Salt Lake as well as on eastern table salts. Results on the local salt were as follows, obtained by dissolving 25 to 30 grams of the salt in hot water and immediately smelling the solution: Undried crude s a l t . . . . . . . . . . . . . . . . . . . . . . . . . . Dried coarse salt.. . . . . . . . . . . . . . . . . . . . . . . . Stock salt, unscreened. . . . . . . . . . . . . . . . . . . . Hav salt. fine.. . . . . . . . . . . . . . . . . . . NO: 2 coarse s a l t , . . . . . . . . . . . . . . . . . . No. 1 coarse s a l t . . . . . . . . . . . . . . . . .,. 40-mesh table s a l t . . . . . . . . Dairy s a l t . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Salt from stock pile Extra coarse kiln-dried Coarse kiln-dried Hay salt Unscreened stock salt No. 1 salt KO 2 salt 40-mesh table .alt Butter salt
IKSOLUBLECas04
Na?SO4
MgCIz
5%
70
c/o
7
0.037 0.025 0 020 0 018 0 028 0 037 0 019 0 010 0 011
0.557 0.346 0.378 0.374 0.369 0.249 0 384 0 204 0 132
0.070 0.065 0.044 0.071 0.041 0.014 0.053 0.055 0.033
0.043 0.043 0.043 0.077 0,034 0,026 0.043 0.034 0.034
KaCI (by diff.)
0
% 99.3 99.5 99.5 99.5 99.5 99.7 99.5 99.7 99.8
Eastern Salt Used by Butter Makers Although a refined salt of exceptional chemical purity is manufactured from the brines of the Great Salt Lake, it is not used very extensively by makers of butter in the intermountain country. Salt for butter making is practically all shipped in from two eastern salt-manufacturing companies. The butter makers simply say that they believe that they can make a better butter from the eastern salt. For the purpose of finding the cause of this prejudice and a cure for it, this investigation was undertaken.
No odor No odor Strong odor Strong odor Present Present Present Strong odor
It should be noted that the coarser screened salts give little or no odor, while fine salts do so. This may be due to too slow a rate of solution of the coarse salt or too low a percentage of the odor-giving substance in the larger crystals. Roasting Tests Since the vapor pressures of sodium chloride, sodium sulfate, calcium sulfate, etc., at room temperature could scarcely account for any odor, it seemed natural to expect organic compounds as the cause of the trouble. Hence roasting tests were carried out in order t o burn out or volatilize any such substances. Two hundred-fifty gram samples of dairy salt were roasted in a monel-metal dish heated in an electric muffle for varying periods of time and a t differing temperatures. The samples were cooled and then tested for odor-in near boiling water. The results are shown in Table I. A change in color was also noted in roasts made above certain temperatures. The color appeared above about 175" C. while the odor disappeared above about 210" C. with a 10-minute heat. The discoloration would make the salt less attractive and so unsalable for table or dairy purposes, even though the odor is gone. Table I-Effect TEMPERATURE
C. 180 185 200 2 10 220 225 250 275 300
O
SALT
337
180 200 215 225 270 295 300 325 325 I55 200
of R o a s t i n g on Odor and Color of Salt
TIME Minutes
ODOR
10 10 10 10 i. n . 10 10
Strong Strong Slight Slight None
10 10 5 5 5 5 i
5 5
5 3 15
15
None
None None h-one Strong Slight Slight None h-one None None None hTone Strong Slight
COLOR White White Slight darkening Slight darkening Slight brown or rustv Sljght brown or rust$ Slight brown or rusty Slight brown or rusty Slight brown or rusty lvhite Slight darkening Slight darkening Slj&t brown or rusty Slieht brown or rustv Slight brown or rust;' Slight brown or rusty Slight brown or rusty Slight brown or rusty White Slight darkening
coloration coloration coloration coloration coloration
coloration coloration coloration coloration coloration coloration
A sample of a favorite eastern butter salt gave no odor with boiling water and did not discolor when heated. When the roasted, odorless salt was dissolved in water, the scum was darker in color and more noticeable. The ignited residues from roasted and unroasted salts, as mould be expected, weighed the same. Before ignition, the unroasted insoluble
I N D U S T R I A L A N D ENGINEERING CHEiMISTRY
338
matter on the filter paper was light gray, the roasted residue dark brown. Both residues contained appreciable iron and analyses indicated that they were chiefly clay. Ignition caused the oxidation of ferrous to ferric iron and the increase of brown color. Some darkening might have been due to mere charring of organic matter. To prevent the discoloration of the salt and a t the same time remove the cause of the odor, samples of crude salt were roasted before crushing, the idea being that the clay and dirt would follow the finer sizes when the salt was screened and leave a clean white core. This is the practice actually followed a t the refinery but on salt that has been heated only to 300,' ,F. (150' C.). The roasting wa8 for 5 minutes on the coarse salt, then i t was crushed and screened. It all passed through a 28-mesh screen. A much cleaner salt was obtained by this treatment, but it was not all that was hoped. The fines and dust held some odor even when heated a t the higher temperatures. T a b l e 11-Effect
ODOR TEMPERATURE 28-65 MESH 0 c. _. iRn ---
Stronp. SlightSlight Shght Slight Slight None None None None
200 225 250 260
285 300 315 345 375
of R o a s t i n g b e f o r e C r u s h i n g ODOR -65 MESH COLOR Stronc Strong Strong Strong Strong Strong Slight Slight Slight Slight
White Slight darkening Slight darkening Slight darkening Slight darkening Slight darkening Slight darkening Slight darkening Slight darkening Slight darkening
Even the coarse salt was somewhat darkened above 300 O C. in 5 minutes. It should be noted that it is more difficult to remove the odor-causing substances from the coarse than from the fine salt, so apparently, whSe most of the impurities are on the surface of the crystal, some are inside. Access of the air seems necessary. It had been noted that the crude, undried salt gave very little or no odor but that after some heating the odor would appear. Crude salt was heated as shown, ground to pass a 35-mesh sieve, and then tested for odor. T a b l e 111-Effect of H e a t i n g C r u d e , U n d r i e d S a l t TIME TEMPERATURE ODOR Minulcs c. 1440 (24hrs.) Room Slight 16 --
15 15 15 15 15 15 15
100 - .
110 130 140 160 185 200 286
~
Slirrht Slight Slight Strong Strong Strong Less strong Slight
No effort was made to screen out the dust, so the odor may have been with it, but these results would lead one t o think that heating up to perhaps 17ij-2OO0 C. simply causes a partial decomposition of compounds present to increase the odor test, while increased heating destroys them. Effect of Crushing and Washing
T o remove any surface impurities and so get a purified salt, 500-gram samples of crude, undried salt were ground t o pass a LO-mesh screen. This product was washed or rinsed in a saturated salt brine, drained, and then roasted a t 250" C . for 15 minutes. The salt was ground t o pass a 35-mesh sieve and tested for odor. A clean, white, odorless salt resulted. The same process of washing was then carried out without the preliminary crushing to 10mesh. This also gave an odorless white salt. Roasting Temperature Required to Remove Odor
Tests were then made on brine-washed salt to discover at what temperature the odor disappears. Each sample was
Vol. 23, No. 3
roasted for 15 minutes a t the temperature indicated, with the following results:
c.
175. . . . . . . . . . . . . . . Slight odor 200.. Very slight 225 ............... None
.............
Other samples were roasted up to 350 C. in order to compare the color with that of ordinary salt when roasted. No discoloration appeared and the roasted salt was as white as the unroasted dairy salt. Cause of Odor Unknown
Attempts were made to collect su5cient of the odoriferous substance to obtain tests for nitrogen or sulfur, but they were unsuccessful. We have then no data as to the compounds which cause the odor. Ordinary U. S. P. Epsom salts were roasted a t about 250" C. for 15 minutes, then tested for odor by adding hot water. The originally strong odor had aImost entirely disappeared, 80 its cause is very likely similar t o that in the sodium chloride organic matter. Most eastern salts gave odors a t least as strong rn Great Salt Lake salt. One salt, according to the manufacturers, wm refined as follows: "In the refining process the natural salt crystal is dissolved in distilled water. The brine thus formed is evaporated in multiple-effect vacuum pans which remove impurities and insoluble matter." Odor Tests on Salt after Heavy Rains
Last autumn, following the draining of the salt ponds-for the harvest, heavy rains fell, and it was thought that these rains might have washed off the salt crystals sufficiently t o get rid of the odor. This salt had not yet been piled, but was collected from the bed of the pond. It was dried, heated for 15 minutes, and ground with results as follows: O
c.
................. SS tt rr oo nn gg odor odor ................. ................. Slight odor ............... Very slight odor
110 150 200 300..
This crude salt was then washed in brine, roasted for 15 minutes, ground, and tested for odor as before. c. _. 125 100.. 230.................
................. Slight odor ............... Very slight odor N o odor Conclusione
1-The substances present in refined salt which cause a n odor when the salt is dissolved in hot water are present in such minute quantities that their identification is not easily possible . %This odor is eradicated by heating fine salt in an olddizing atmosphere to temperatures above 210' C. +Roasting of ordinary refined salt is not a commercially practical step because of the discoloration which appears. This discoloration is probably due to the oxidation of the iron of light colored clays which are swept in by the winds from the nearby flats and tailing ponds. A slight amount may be due to charring of minute quantities of organic matter. These clays are present only to the extent of about 0.01 to 0.15 per cent in the present refined salt. 4-A white, clean, practically odorless salt is obtained by washing with brine and then roasting. Temperatures above 225' C. are not considered necessary. %The odor is apparently due to a very small amount of organic matter which is on the crystals as they come from the pond. The odor with hot water appears only after the or-
March, 1931
INDUSTRIAL AND ENGINEERING CHEMISTRY
ganic residues are partJy decomposed by time or gentle heating, as in refinery drying. If the temperature is raised sufficiently, the organic compounds appear to be completely destroyed. M i n c e rinsing with brine very largely removes the source of both color and odor, these must be due to some sort of deposit on the crystals as they come from the ponds.
339
7-It would appear that on a commercial scale the crude salt could be given a brine wash and a whiter and purer dairy and table salt produced. After washing, only drying a t slightly higher than present used temperatures would be needed. The washing removes the clay and most of the organic film; the heating destroys the remainder of the odorproducing substances.
AMERICAN CONTEMPORARIES Charles Edward Coates
I
T WAS in the fall of 1908 that I first met Doctor Coates at
Church of Baton Rouge, and has devoted much of his spare the old Sugar Experiment Station in Audubon Park, New time to the promotion of Boy Scout activities. His personality has always endeared him t o his students and Orleans. I saw him surrounded by a group of students who the graduates of the Audubon Sugar School, of which he is dean. seemed deeply interested in his every word and gesture. I noted that the earnestness of the conversation was broken a t fre- These men are scattered throughout every cane-sugar country quent intervals by outbursts of merriment, as the teacher di- of both hemispheres. Somebody once said, “The sun never sets on the graduates of the Audubon Sugar gressed for the moment from his lecture to School.” A few years ago the writer atenliven the period by one of his well-chosen tended the congress of the International witticisms. He was then on a visit of inSociety of Sugar Cane T e c h n o l o g i s t s in spection to his fourth-year sugar-engineerHavana, Cuba, one of the features of which ing students who were a t Audubon Park was a tour of the island. On this tour the for their practical training in sugar-factory dean of the Audubon Sugar School would operations. He seemed to me that mornbe greeted a t every central and almost every ing to be more in the role of a head coach station by some of his former graduates. to his students, and throughout the quarter Indeed the first question asked by former of a century which has elapsed since our L. S. U.graduates of visitors from Louisiana first meeting, that impression of him has to Cuba, or any other of the sugar-producseemed the most lasting of the many that ing countries in the tropics, is always, “And contacts with him have left with me. how are Charlie Coates and the Audubon Doctor Coates is the son of C. E. Coates Sugar School?” and Anna Hunter Coates, of Coatesville, Doctor Coates has always maintained and Pa., where his forebears have lived since acted upon the belief that the teacher must 1690. He was born in Baltimore, Md., on do far more for his students than merely August 13, 1866, received his doctor’s deimpart sufficient knowledge to enable them gree from Johns Hopkins University in 1891 after having studied in Friedberg and Heidelto pass with credit, or even distinction, berg, in Germany, in 1888 and 1889. the examinations leading to the desired deFor many years he has s p e c i a l i z e d in grees. He believes that education, no matter how specialized its u l t i m a t e object the technology of the sugarcane, cotton, Charles E. Coates may be, is first and last to make men and petroleum industries. His D i o n ee r work on hydrocarbons in Louisiana petroleum is well known. and women capable of becoming good citizens whose influence He is regarded as the dean of sugar chemists in the United and culture may redound to the good of their communities and States. the enrichment of their own individual experiences. To this One might write of the honors that have come to Doctor Coates end he never loses an opportunity to use his influence in developand of the monument that he has erected in the great Depart- ing character among his students. How lavishly he has given ment of Chemistry which he has built a t the Louisiana State of his time in advising and assisting his students, no one but those University in the face of hardships and discouragements which intimately associated with him fully realize. Each year there would have disheartened many. He likes to talk of the days come under his tutelage increasing numbers of freshmen, and when he and his one assistant, Doctor Menville, did all the teach- to each class he seems to address himself with undiminishing ing in the department and handled most of the miscellaneous zeal in order that they may meet the vicissitudes of university analytical work as well. life just a little bit better than their predecessors. Many interBut these glimpses of Doctor Coates leave the best part of esting stories might be related of the innumerable occasions when the picture obscured, for those who know him can never think he has reached out a kind and sympathetic hand to a wavering of him merely as a teacher, or a great scientist, or a student, but student and has sustained him through periods of unrest and deas a man whose influence has touched his fellow men in every pression. One might also write of his lectures, which are so walk of life, and through its warmth and kindness has always illuminating, and yet so artfully interspersed with anecdotes tended to make life more worth while and more enjoyable for and reminiscences, that the students find them far too interesting others. One must think of him in relation to his community, to even wish to “cut.” to the upbuilding of which he has contributed so much of his However, it is in his own home that one comes to know him time and his efforts. Few are the civic, social, or industrial move- best. Here in this inspiring atmosphere, to which the charm of ments in his home city with which he is not closely identified. Mrs. Coates contributes immeasurably, one listens t o discussions He has been for many years a junior warden in the Episcopal of literature, art, science, or affairs of the day, and then realizes
