T H E J O U R N A L O F I N D U S T R I A L A N D ENGIiVEERING C H E M I S I ‘ R P
2 I4
May t o recover i t from t h e filtrates from determinations of phosphorus. Various methods were tried before t h e present one was settled upon as giving t h e best recovery with t h e least work and expense. The method consists of t h e precipitation of t h e molybdic acid from t h e ferric nitrate solution with a n excess of phosphate. At first t h e theoretical amount of phosphorus was added t o t h e cold solution a n d b u t t h e molybdic acid was recovered. At t h e present time five times t h e theoretical amount of phosphate is added t o t h e boiling solution. It has been t h e practice in this laboratory to make lb. lots of 85 per cent molybdic acid, t h e acid in ‘/z making 3500 cc. of solution a n d in agreement with t h e adopted method of t h e U. S. Steel Corporation. T h e filtrates from 3500 cc. of ammonium molybdic solution are heated t o boiling a n d a solution containing 2 0 0 g. commercial sodium phosphate added. The precipitate is allowed t o settle and, after t h e solution is decanted, is transferred t o a large-mouthed bottle. When sufficient yellow precipitate from several precipitations is obtained, i t is washed by decantation, transferred t o a dish, t h e water evaporated off and t h e precipitate dried on a sand bath. According t o t h e commonly accepted formula for t h e yellow precipitate, i t contains 92 per cent Moo8, a n d 2 1 0 g. would contain t h e same weight of acid as ‘/zlb. of 8; per cent molybdic acid. Accordingly, for t h e precipitation of t h e molybdic acid solution, 2 1 0 g. of yellow precipitate are weighed and 800 cc. water added, followed by 600 cc. ammonia. The solution is cooled and 35 g. magnesium nitrate, dissolved in I O O cc. water, are added t o precipitate all t h e phosphorus. After the solution has stood for some time i t is filtered and t h e precipitate is washed with I O O cc. water or dilute ammonia. The filtrate is added t o 1900 cc. of I : I nitric acid, t h e total volume being 3500 cc., and containing t h e usual amount of ammonia a n d nitric acid. I n this laboratory t h e recovery has been only about 85 t o 87 per cent. The cost of recovery of one pound of molybdic acid is about IO cents: 7 cents for t h e sodium phosphate and 3 cents for t h e magnesium nitrate, the ammonia being required in t h e ammonium molybdate solution. DUQUESNE WORKS,CARKEGIE STEELCo.
DUQUESNE, PA.
THE MODIFICATlON O F STARCH BY GASEOUS HYDROCHLORIC ACID
e. F R A R Y AND ARTHUR C. DEKNIS Received Sovember 23, 1914
By FRANCIS
Very little information on t h e actual manufacture of dextrin from starch is available. Text-books1 generally state t h a t it is made clear either b y heating starch alone t o from 2 1 0 t o 2 8 0 ’ C., producing a brown product, or by moistening t h e starch with dilute nitric acid a n d heating a t a lower temperature ( 1 1 0 t o ljoo e.)* It appears t o be well known t h a t dilute acids a n d some other substances have t h e power of modifying starch more or less in t h e cold, producing so-called “thin-boiling )’ starch, without breaking 1
Allen’s “Commercial Organic Analysis,” 3rd Ed., 1, 49.
1701. 7 ,
KO.3
down t h e granules so t h a t they are dissolved by cold water. After such treatment t h e excess of t h e reagent may be washed out and t h e starch dried as usual. Among t h e substances recommended (and in most. cases patented) for modifying starch are persulfates, bleaching powder, sodium peroxide, bichromates, ozone, formic acid, oxalic acid, tartaric acid, salts of t h e heavy metals (copper, nickel, cobalt, iron, etc.), carbon dioxide a n d formaldehyde. ,4 second step in t h e modification of starch consists in submitting i t t o such treatment as t o rupture t h e cellulose envelopes of t h e granules, thus making t h e starch emulsify in cold water t o form a liquid like ordinary boiled starch paste. If this be accomplished in t h e dry way, t h e form of t h e starch is unchanged, b u t upon mixing it with cold water i t dissolves as if it had been boiled. Such pastes are made in this country b y a number of manufacturers, t h e raw material being apparently a low grade of flour. The only information obtainable as t o t h e process of manufacture is t h a t it is a very cheap one, as the finished product sells for little more t h a n the raw flour. F r o m t h e appearance of some samples received by one of us; some of t h e plants are apparently using t h e wellknown process of Anderson,l which consists in heating t h e starch in closed vessels t o over 100’ C., and t h e n suddenly releasing t h e pressure. The granules are ruptured by t h e espankion of t h e steam in. them. It is interesting t o note t h a t this patent of A4nderson’s for making soluble starch, preceded and seems t o have been a preliminary step toward his more important patents fo.r “puffing” grains. Other patented treatments which appear t o aini t o produce t h e same modification of starch were also found. Fielding2 treats starch with acid vapors a n d steam t o produce a soluble starch. Thompson and rVIorrice,3 a n d Thompson a n d Berge4 use sulfurous acid a t temperatures from 100 t o 190’ C , , while Kindscher5 used chlorine. HartwigGalso uses chlorine, specifying a treatment of from four t o eight days’ duration. Browning and Barlow7 use hydrochloric acid gas, or a spray of t h e aqueous acid, passing it into a rotary converter containing t h e starch. T o produce a soluble starch a temperature of 54’ C. is recommended, while for dextrin t h e temperature is said t o be 76 to 93’ C. From a general consideration of the question, it, appeared t h a t treating t h e starch with a small amount of gaseous hydrochloric acid. and heating it, would be t h e simplest method of producing soluble starch, and experiments h a d been begun and favorable results secured b y one of us before we found t h e patent of Browning and Barlow, Believing t h a t their process would be of general interest and t h a t a study of it might yield interesting information, a series of experi1 U. S. Pat. 707.892; Brit. Pat. 13,353, June 12, 1912; J . Sac. Chem. Ind., 21, 1189. 2 Eng. Pat. 20,488, Sept. 15, 1906; J . SOC.Chem. I n d . , 26, 980. 3 Fr. Pat, 383,499, C . S. Pat. 991,666; C. A , , 3, 1104; 4 , 1556. 4 Eng. Pat. 7 , 2 7 2 , Apr. 27, 1891; J. Sac. Chem. Ind., 11, 418. 5 Ger. Pat. 168,980; J . SOC. Chem. I n d . , 26, 334; see also Ger. Pat. 149,588. 6 U. S. Pat. 798,509; J . Sac. Chem. Ind., 2 4 , 1024. 7 Fr. Pat. 336,903; J . Sac. Chem. In&, Z3, 449.
I
Mar.,
IgIj
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
ments was carried out to determine t h e relation between t h e quantity of acid present, t h e temperature used a n d t h e character of t h e product. Further study of t h e products a n d t h e relations a t higher temperatures was contemplated, b u t was prevented by Mr. Dennis leaving t h e University. As there seems t o be n o prospect of our being able t o complete t h e work at present, these preliminary results are published in t h e hope t h a t t h e y m a y be of value in indicating t h e course of t h e reaction. The starch used was made b y powdering t e n pounds of common laundry starch until about 7 0 per cent of i t passed a loo-mesh screen. T h e rest appeared t o be tough a n d glutinous, a n d did not crush well, so it was rejected. After thoroughly mixing a n d allowing t h e sample t o stand in a large glass-stoppered bottle, a moisture determination showed I 2 . 7 per cent loss on drying a t 105’ C. The sample contained 0 . 2 0 per cent of ash. Care was taken t o keep t h e bottle tightly closed in order t o maintain t h e moisture content constant throughout t h e series. Twenty grams of starch were used for each experiment. T h e starch was placed in a n improvised revolving mixer and dry hydrochloric acid gas (made from salt and sulfuric acid, a n d dried with sulfuric acid) was passed into t h e mixer. It was rapidly absorbed. The amount of acid absorbed was determined by titration of a I g. sample with N / I O alkali, using methyl orange a n d phenolphthalein as indicators. . For heating t h e starch a glass apparatus like a Liebig condenser was used, hot water being rapidly circulated through t h e jacket by means of a small centrifugal pump. For higher temperatures calcium chloride Time Min. 40
..
30 30 30 30 20 30 1; 20 30 30
..
30
;;
TABLEI PER CENT ACIDFOUND BY Cold Temp. Phenolphthalein Methyl Orange water C. before after before after paste 60 0.83 0.80 0.47 No 80 80 90 80 80 95 100
8%Loo/ 90 80 70 65 60
I::
0.33 0.77 0.77 1.24 0.15 0.72 0.91 1.63
0.33 0.73 0.69 1.09 0.18 0.77
2.10 2.29 2.47 2.06 5.52 4.13
1.96 1.74
0.15
..
.. ..
2:97
o:is
0.11 0.51 0.47 0.80 0.03
NO
0.61 0.73 1.42
0.11
No
..
No No
1.81 2.06 2.18 1.88 5.22 3.88
1.67 1.56
No No Yes No No Yes
0.58 0.54 1.02
0.11
0.43
..
3:88 2.76
No No Slight PITO
DI~X‘CRIN No@) NO(^)
Trace@) .
I
.
Trace@) No@) Yes Yes Yes(e) Yes(e) Yes(e)
...
h1o
Yes Yeso
Yes Yeso Trace No No Yes Trace ,. ... Some .. Yes 6; *.. .. /> Yes .. 30 90-95 ,. .. Yes ‘*30 60-65 ,. .. Yes 30 62-65 Yes .. 30 54-56 No Ye’& 30 48-50 , Yes 5.87 .. ... 30 39-41 ,. Yes ... 30 35 . . Yes .. . ( h ) 30 40 Yes . . (h) (a) 20-25 5:40 Yes ... 30 48 4:j2 . . Yes ...(i) .. 30 68 1.63 .. Yes . . . Li) .. 30 33 .. . . 6 . 9 0 . . Trace No(k) 30 55 .. 3.52 ., Yes .. NOW 30 50 .. 3.70 .. No Noh) 30 45 .. No . . 4.94 No(%) ( a ) This was allowed to stand over night at room temperature, and is not included in the plot because of this long time of treatment. ( b ) Slight opalescence with alcohol. (i) Some unchanged starch. (6) Precipitate with alcohol. ( A Much unchanged starch. (d) Opalescence with alcohol. ( k ) Almost unchanged. (e) Good gextrin. (1) About half converted. (f) Sticks well. (m)Very slightly changed. (9) White, just converted. (n) Almost unchanged. ( h ) Some unchanged starch. 30 20 30 30 30 30
100 105 63 60 82
0.40 0.22 3.48 2.24 1.26 3.45 1.63 0.73 3.27 2.54 5.08
0.36
..
.. .. .. ..
..
..
..
..
..
.. ..
0 33 0.15 3.27 2.07 1.12 3.19 1.48 0.58 2.97 2.40 4.72 5.45 7.44 7.91 6.97
0.25
.. .. ., ., .. ..
.. ..
I . .
.. .. .. ...
.
.
215
was added t o t h e water. A bent glass tube revolving inside t h e inner t u b e stirred t h e starch thoroughly. Both ends of t h e inner t u b e were closed with rubber corks t o prevent loss of moisture. The time of treat-
ment was generally about thirty minutes. T h e results are presented in t h e accompanying table a n d curves. It will be noticed t h a t t h e acidity t o phenolphthalein was greater t h a n t h a t t o methyl orange, a n d where determinations of acidity were made after t h e treatment, decrease of acidity t o both indicators was shown. In plotting t h e results, t h e acidity t o methyl orange was used, as it is believed to more closely represent t h e acidity effective in t h e hydrolysis of t h e starch. Under t h e conditions described, i t is evident t h a t for a given acidity there is a definite temperature range within which a half hour’s heating will convert t h e starch t o t h e soluble variety (called “Cold Water P a s t e ” in t h e table); at higher temperatures t h e conversion t o dextrin is rapid, a n d a t lower temperatures little change takes place. Longer treatment a t lower temperatures would undoubtedly effect some change, as indicated in one experiment in t h e table, where t h e acid starch was not heated a t all, b u t simply allowed t o stand over night a t room temperature, a n d a cold water paste was obtained. Similarly, for a given temperature, t h e range of acidity within which a soluble starch is produced is definite, greater quantities of acid-producing dextrin a n d smaller quantities failing t o produce t h e soluble starch. The smaller t h e amount of acid present, t h e higher t h e temperature required t o convert t h e starch, a n d apparently t h e more difficult i t would be t o stop at t h e point where t h e soluble starch was formed. The dextrins produced were generally very nearly white a n d had good adhesive power. The proportion of water present in t h e starch was so large t h a t when t h e dextrin was formed it h a d a strong tendency t o dissolve or melt in t h e water, forming lumps which
216
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
stopped t h e stirrer. I n some of t h e first experiments, t h e treated starch was washed with cold water, a n d t h e behavior of t h e resulting solution noted in t h e table. The opalescence a n d precipitates with alcohol indicate t h a t t h e reaction does not proceed in two definite, separate steps, b u t t h a t dextrin begins t o be formed in small quantities as soon as t h e soluble starch formation begins. Undoubtedly all products designated as “Cold Water Paste’’ contained a good deal of dextrin. It would be comparatively easy t o remove or neutralize t h e small amount of acid required if t h e conversion t o dextrin were made a t 100’ or over, a n d i t would appear t h a t this would be a n easy way of making a good white dextrin. If t h e starch were dried somewhat before use, less acid would probably be required a n d t h e product would not lump, hence would not need grinding. The method does not seem very well adapted to producing soluble starch, and i t is evident t h a t t h e temperatures given for this b y Browning a n d Barlow require t h e use of larger quantities of acid t h a n would be economically practicable, unless t h e time of treatment were much increased. SCEOOLOB CEEYISTRY UNIVERSITY:OF MINNESOTA. MINNEAPOLIS ___--
THE DIRECT:AND THE INVERT POLARIZATION OF PURE SUCROSE’ By HERBERT S. WALKER
Considerable doubt has arisen in .recent years as t o t h e correctness of our present polarimetric methods of determining sucrose. At t h e last International Congress of Applied Chemistry a paper was presented by Bates and Jackson, indicating t h a t t h e I O O point of t h e saccharimeter is approximately 0 . I O too high. This subject was deemed of sufficient importance t o warrant appointing a special committee for its investigation, t o report a t t h e next meeting of t h e Congress. At t h e same session, on motion of Prof. Herzfeld, a committee was also appointed t o re-determine t h e correctness of t h e factor 1 4 2 . 6 6 now used in t h e ClergetHerzfeld method for t h e determination of sucrose b y double polarization. Since then, investigations b y Steurwald, in Java, a n d Stanek, in Bohemia, t e n d t o prove t h a t t h e Clerget factor 1 4 2 . 6 6 is from 0 . 2 t o 0 . 3 too low, Stanek claiming, however, t h a t if t h e invert polarization be made within 5 minutes after completing t h e volume of t h e inverted solution, t h e original Herzfeld factor holds good, but owing t o a slight muta-rotation of t h e invert sugar, a constant invert polarization is not reached until 15 t o 20 minutes after completing t o volume. Both these investigators apparently find, or assume, t h e direct polarization of pure sucrose t o be 100.0. Since i t will probably be several years before reports from t h e committee officially appointed t o investigate these two subjects may be expected, t h e following experimental d a t a may be of some interest: A n a t t e m p t was made t o prepare pure sucrose by t h e customary method of precipitation from a hot, f Paper presented a t the Annual Meeting of the Hawaiian Chemists’ Association, October 22, 1914.
1’01. 7, NO. 3
saturated solution by absolute alcohol, starting with t h e best grade of “domino” sugar. The sugar t h u s obtained was re-dissolved, re-precipitated, washed on a suction filter with alcohol, and finally air-dried DETAILS OF EXPERIMESTS
8- H. N O . 8800, double field. W, concentrated filament tungsten. LIGHT FILTER-3 cm. of 3 per cent potassium bichromate soluSACCHARIMETER-3.
LIGHT-100
tion. 100 POIKT OF INSTRCXENT verified to 0.01 by comparison with a quartz plate standardized by the Bureau of Standards. TUBE LENGTH-~eaSUred by a standardized comparator to 0.03 mm. FLASK used for making up solutions for direct polarization and for inversion made with special narrow neck-calibrated to 0 0 2 cc.
CONCESTR.4TION
OF
SOLUTIONS FOR DIRECT POLARIZATIOS-
determined by weight as well as by volume, then calculated to grams solids per IOO cc., thus eliminating correction for moisture in the sugar and giving concentration exact to G O I g. per IOO cc., or 0.004’ V. VOLUME O F SOLUTION CSSD FOR IxvERsro;v-checked by weight. After inversion and completion to volume, cooled solution was placed in the same “inversion tube” used for direct polarization and allowed to stand for approximately half an hour in the saccharimeter trough till it had assumed the same temperature as the instrument and the atmosphere, before reading. WEIGHTS UsED-corrected to 0.0001 g. by standard weights. THER~fOMETERS-Corrected by gas thermometer. “PROBABLE: ERROR” OF READING INSTRUMENT (average of I O readings)-For direct polarization 0.01O V. For invert polarization 0.02 O V.
for several days. It was then found t o contain: Moisture, 0 . 0 2 per cent; ash, 0 . 0 0 4 per cent; reducing sugars, less t h a n 0 . 0 1 6 per cent (using Ost’s solution). The direct polarization of this sugar, using 2 6 . 0 0 0 g. dry sugar (weighed in air with brass weights) in I O O true cc. was, a t 22.0’ C., after adding 0 . 0 6 for temperature correction, 99 86. Adding 0 . 0 2 as a correction for reducing sugars and ash would give 99.88 as t h e polarization of 26 g. pure sucrose dissolved in I O O true cc. solution a t zoo C. Fifty cc. of t h e solution used for direct polarization were then inverted by the Herzfeld method and eventually polarized a t 2 2 . 2 ’ C. Using t h e factor 142.66, t h e calculated per cent sucrose of this sugar, corrected for reducing sugars a n d ash, was 100.07. ,4s a check on the above determination, a sample of pure sucrose was obtained from t h e Bureau of Standards, Washington, D. C. I t s certified analysis was as follows: hloisture, 0 . 0 0 2 per cent.; ash, 0 . 0 0 2 per cent; invert sugar, less t h a n 0 . 0 0 3 per cent. I t s direct polarization. then, should exceed 99.99’ At 23 95’ C. t h e direct polarization actually found was, corrected for temperature, 9 9 . 9 0 . Its sucrose by t h e Clerget-Herzfeld method. using t h e factor 142 66, was T O O . 09, showing a difference between direct polarization a n d “sucrose b y Clerget” of 0 . r g per cent. From t h e last experiment i t appears t h a t t h e CIerget factor, if designed t o give a reading of IOO per cent e
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