Sept., 1916
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
as “Vierge Egyptien” (combustible), a n d measure about 1560 meters t o t h e reel. The average width of these papers is 30 mm., having a n average weight of 18.75 g. t o t h e square meter and a corresponding thickness of about 0.0014 in. METHODS O F ANALYSIS
determinations should be made according t o Bureau of Chemistry, Bull. 107, 14. ASH-The sample used for moisture determination was incinerated over a Tirrill or Bunsen lamp, using a very low flame, then t h e ash removed to a blast flame and incinerated until no further loss in weight was observed. [This ash should show only a slight effervescence or none a t all, when i t is suspended in water and treated with a few drops of concentrated hydrochloric acid (absence of carbonates).] FIBER (PULP)-IO.OOO g. of finely cut paper were weighed into a liter Erlenmeyer flask and 500 cc. of distilled water and 10.0 cc. of hydrochloric acid (sp. gr. 1 . 2 0 ) were added. The mass was boiled over a free flame for I hr. or until t h e whole was well pulped, then filtered on a Buchner funnel, using a tared, acidwashed hlter, and washed with water until a drop of t h e filtrate showed only a slight opalescence when tested in t h e usual manner for chlorides. The filtrate was preserved for determination of t h e constituents of t h e ash. The pulp was washed three times with 9 j per cent alcohol, packed well with a glass rod, removed t o a drying oven and dried t o constant xeight a t I o j o C. The pulp was then reduced t o ash and the ash found subtracted from t h e weight of t h e pulp. along with t h e weight of t h e filter paper used, from which a n y ash value it might have had has been subtracted. This gives t h e weight of pulp by difference. MINERAL FILLER is calculated by difference, b y subtracting the combined weights of moisture, fiber and size from IOO per cent. As a check on t h e determination of mineral filler, t h e constituents of t h e ash were calculated t o t h e compounds occurring in t h e paper and this total weight compared with t h e filler as found b y difference. SIZING, COATING, KINDS O F FIBER, ETc.-These constituents were determined according t o the methods laid down in Allen’s “Commercial Organic Analysis,” 1, 473-479 (4th E d . ) . MOISTURE
ANALYTICAL RESULTS(PERCENTAGES) SAMPLE: 1 2 3 4 5 4.05 4.14 Moisture ......................... 3.99 4.30 4.62 Ash (as oxides). . . . . . . . . . . . . . . . . . . . 12.25 12.07 12.95 4.95 5.12 71.07 71.35 7 2 . 5 7 87.08 85.74 Fiber (pulp).. .................... 24.88 24.10 23.19 8.62 9.64 Filler ............................ 1.00 1.00 1 . 0 0 0.10 Size (less than) .................... 0.10
C O X S T I T C E N T S O F T H E ASH-The compounds which occurred in t h e ash were calculated in t h e usual manner by t h e official methods as laid down in Bureau of Chemistry, Bull. 107, e. g., CaO (p. IS), MgO (p. 16) and (Fe L41)20;(p. I j ) . As a check on t h e above ash determination, t h e filtrate from t h e fiber determination was evaporated t o dryness and t h e acid expelled. This residue was taken u p in a convenient volume of water and t h e compounds present determined as above.
+
COMPOSITION OF THE ASH (,PERCENTAGES) 3 4 1 2 4.39 Calcium oxide. 12.06 11.74 11.01 0.20 1.29 0.26 Magnesium oxide.. ................ 0.17 0.30 0.24 Aluminum oxide. Trace Trace Iron oxide.. ...................... Trace Trace Silica., .......................... Trace None HzS precipitate. . . . . . . . . . . . . . . . . . . . None Sulfates. ......................... None None None None None None None Nitrates.. ........................ Chlorides.. Trace Trace Trace Trace
SAMPLE:
................... .................
.......................
813 5 4.30 0.24 0.11 Trace Trace None None None Trace
As a check on t h e above results, Samples I and 2 were compared with t h e compounds found in t h e filtrate from the pulp determination. The following gives a comparison : SAMPLE: l(a) l(b) 2(a) 2(b) 11.74 11.69 11.76 Calciumoxide.. ................... 12.06 20.95 20.87 21 .OO Calcium carbonate.. . . . . . . . . . . . . . . . 21.52 0.26 0.33 0.15 Magnesium oxide.. ................. 0.17 0.54 0.67 0.31 Magnesium carbonate(c). . . . . . . . . . . . 0.36 (a) Result from ash. (6) Result from filtrate from pulp. The other traces showed up the same in both samples. (c) 3MgC03.Mg(OH)z.4HzO.
FIBER A N D SIZING-A~~ fibers were found t o be linen. Sizing in t h e first three were found to be dextrine a n d t h e last two carried traces of starch but no dextrine. COMPOSITIOX O F T H E P A P E R
T h e composition of t h e papers appears t o be: linen fiber slightly sized with starch or dextrine and filled with t h e carbonates of magnesium and calcium. T h e filler in t h e first three avkraged 24.05 per cent, while t h e last two showed a n average of 9.13 per cent. The fillers were calculated t o the carbonates, while it is possible t h a t a portion of t h e magnesium was added as t h e peroxide or oxide for accelerating t h e burning of t h e paper. This change would not affect the resulting weights appreciably. SUMMARY
Kothing injurious was found in t h e ash, filler o r pulp. The paper burns t o a clean white ash which shows good combustion and t h e absence of compounds formed by destructive distillation. The filler is not materially changed when t h e paper is burned, so has no effect except t o promote combustion and t o make t h e papers “tight.” No tests were found for alkaloids or alkaloidal salts. N o poisonous metals were found (absence of hydrogen sulfide precipitate). N o bad effect was had from t h e small amount of sizing, as is evidenced b y the good burning qualities and t h e absence of compounds formed by destructive distillation. CHEMICALDEPARTMENT, THEAMERICAN TOBACCO COMPANY AvE., BROOKLYN, NEW YORE 60-62 FRANKLIN
TIN IN CANNED FOODS By W. D. BIGELOW Received July 17, 1916
I t has long been known t h a t the acids of canned fruits dissolve more or less tin from the container, t h e amount depending partly on t h e age of the product and t h e temperature of storage. I t is also well known t h a t some foods having but a slightly acid reaction, such as pumpkin, string beans, and shrimp, attack tin t o a considerable extent. This has been shown’ t o be due in some cases at least t o t h e presence of amino bodies in t h e food. The tin in canned foods has usually been assumed t o be in solution. Articles on this subject and reports of analytical work frequently refer 1
Bigelow and Bacon, Bureau of Chemistry, Circ. 79.
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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
t o the tin contained in the food as (‘soluble tin salts.” It was pointed out b y t h e writer’ some time ago t h a t the tin in canned food was largely, sometimes chiefly, in some insoluble form. I t is a common experience in the laboratory t h a t compounds of tin separate out from reagent solutions of tin chloride. This is ordinarily prevented b y the use of strong hydrochloric acid. The same separation occurs with solutions of compounds of tin with organic acids. It appears, therefore, t h a t t h e acid acts as a carrier dissolving the tin from t h e coating of the container and carrying i t into t h e food where the tin separates in a n insoluble form, leaving the acid free. With nonacid or slightly acid foods of the types mentioned above, this deposition of tin in insoluble form probably occurs t o a greater extent t h a n with t h e acid fruits. I n both cases it appears t h a t a considerable proportion of the soluble tin salts is carried within t h e solid particles of food before being hydrolyzed. It is conceivable t h a t the higher tin content of t h e drained solids t h a n of the liquor might be due t o metathesis, the tin replacing calcium or magnesium, for instance, in its insoluble cognpounds within the solid particles of food. The property of solutions of tin salts, however, to deposit insoluble tin compounds, a n d especially the property of stannous solutions t o yield insoluble basic stannic compounds: appears t o afford a more probable explanation of t h e presence of insoluble in place of soluble tin compounds in canned foods. I n either case t h e drained solids of canned foods contain a materially higher amount of tin t h a n t h e liquor, and this difference increases with the age of the sample. Thus the high tin content of old canned foods is largely due t o insoluble compounds of tin which are presumably less likely than soluble compounds t o be absorbed from the intestinal tract. The figures given in Table I were obtained by determining the amount of tin in drained solids and liquor, respectively, and calculating t h e amount of t i n in t h e original sample from the figures thus obtained and from the weight of drained solids and liquor, respectively. TABLEI MILLIGRAMS TINPER KILOGRAM IN Total VARIETYOF FOOD 1,iquor sample Drained solids Cranberries . . . . . . . . . . . . . . . 33 1i o 254 194 294 107 163 193 25 1 Peaches . . . . . . . . . . . . . . . . . . 86 Pears., . . . . . . . . . . . . . . . . . . 99 130 151 125 180 224 381 86 13 1
Vol. 8, No. 9
expressed in terms of milligrams per kilogram of drained solids and liquor, respectively. From these figures, the tin content of the original sample was calculated. By a s t u d y of this data we are able t o form a rough approximation of the amount of tin which is in soluble form. For this purpose it is necessary t o assume t h a t t h e tin of the liquor is all soluble. This is probably not t h e case. I t is extremely unlikely t h a t t h e soluble tin compounds all find their way into the solid particles of t h e food before t h e separation of the tin in insoluble form. It is much more likely t h a t a considerable portion of the tin in the liquor is a finely divided insoluble oxide, hydrated oxide, or basic salt of tin. It is altogether probable t h a t the amount of soluble tin in these samples did not increase after t h e first analyses were made, and t h a t t h e subsequent increase of tin in the liquor was due t o the separation of finely divided insoluble compounds of tin. The thought also suggests itself t h a t a considerable portion of the tin t h a t appears t o be in solution is probably in colloidal form. If we assume all t h e tin of the liquor t o be soluble, therefqre, t h e amount of tin calculated as insoluble will be less t h a n t h e amount actually present in t h a t form and t h e results will a t least be conservative. TABLEI1 Soluble Inqoluble Soluble Age of tin in tin in tin in sample Total Drained drained drained total FOOD Yr. Mo. sample solids L q u o r solids(a) solids(b) sample(a) 200 193 Asparagus. . . 196 1 252 248 249 238 229 233 2 46 38 41 Lima beans.. . 33 40 2 35 60 63 62 String beans.. 61 64 63 1 3 97 95 93 102 98 1 8 100 132 127 6 2 130 38 3 39 39 Wax beans 7 52 50 51 10 55 53 54 69 3 72 71 1 84 87 86 1 8 85 88 4 86 2 (a) The figures in these columns are doubtless higher than they should be as they are based on the assumption that the tin of the unfiltered llquor is all in solution. ( b ) For the reason given in footnote (a), the figures in this column are doubtless lower than they should be. h ~ f L L I G R A h f STIN PER KILOGRAM IN:
VARIETYOF
.
The figures given in Table I1 in the column headed “Insoluble tin in drained solids” were obtained in t h e following manner, taking, as a n example, t h e sample of asparagus which was examined z yrs. and 7 mos. after packing. T h e liquor in this sample contained j . 2 per cent of solids or 94.8 per cent of water. One kilogram of t h e liquor, therefore, contained 948 g. of water. Since a kilogram of liquor contained 238
Sept., 1916
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
per kg., it follows t h a t 5 5 4 - 2 2 9 = 3 2 j mg. per kg. must he in a n insoluble form. As stated above, this amount must he well within the truth. If a n y considerable amount of t h e tin of the liquor is insoluble, t h e insoluble tin of t h e drained solids must he considerably more t h a n 3 2 j mg. per kg. The remaining figures in t h e column marked "Insoluble t i n in drained solids" were all calculated in the same manner, using average figures for t h e weight and water content of drained solids and liquor as t h e individual determinations were not made. The column headed "Insoluble tin in drained solids" is of particular interest although, as stated above, it is believed t h a t t h e figures in this column are somewhat less than t h e t r u t h ; t h e relatiye amount reported as insoluble tin in samples of different ages shows t h a t the process of hydrolyzation is a continuous one. The figures given in t h e last column headed "Soluble tin in total sample" were obtained by adding together the figures in t h e columns headed "Milligrams t i n per kilogram liquor" and "Soluble tin in drained solids," after calculating these respective figures t o milligrams of tin per kilogram of t i n of original sample. I t is interesting t o note t h a t t h e figures in this column are almost identical with t h e figures in t h e column headed "Milligrams tin per kilogram liquor." I t is probable, therefore, t h a t a n approximate idea of the amount of soluble tin in a sample of canned food can be obtained by determining t h e amount of t i n in t h e liquor of t h e food, although t h e figure so obtained will obviously include any insoluble t i n which may be present in t h e liquor in a finely divided state a n d also any tin t h a t may be present in colloidal form. Recent workers agree t h a t t h e ideas of t h e earlier writers on t h e toxicity of t i n were erroneous. I t is now known t h a t t h e toxicity of soluble tin compounds is a t least very much less than it was formerly supposed t o be. I t is evident, however, t h a t t h e results obtained in t h e study of soluble t i n salts cannot be used a s a criterion on which t o judge t h e toxicity of tin in canned foods. Whatever t h e insoluble combination in which t i n occurs in canned foods it is in all probability less likely t o be absorbed from the intestinal tract t h a n soluble t i n compounds. The same is true, perhaps t o a less extent, of t i n in colloidal form. A t any rate, t h e need of experimental work on the toxicity of tin a s it occurs in canned foods is obvious, NA~ONA CANNHRS' L ASSOE~ATION.WASHINGTON
THB EFFECT OF CURING ON THE AROMATIC CONSTITUENTS OF VANILLA BEANS1 B,.
FRANK
me*r
Received March 13. 1916
The fruit of vanilla has long been used a s a flavoring agent. The plant is native t o Mexico, where it is a t present extensively cultivated for t h e production of t h e vanilla beans of commerce. It has been introduced into a number of other tropical and subtropical countries where it is also profitably cultivated. Among the other sources are South America (Guadaloupe), I
Published by permission of the Secretary of Agriculture.
815
Tahiti, Reunion, Madagascar, Comores, Seychelles, and Mauritius. Vanilla beans as found on t h e market are described by t h e United States Pharmacopoeia' a s t h e "cured, full grown, but immature, fruit of Vanilla planifolia, Andrews. (Family orchidaceae.)" Vanilla is used for flavoring purposes in the form of t h e so-called extract or tincture of vanilla, which is prepared by extracting the coarsely comminuted beans with a hydroalcoholic menstruum varying in strength from 4 j t o 6 j per cent. The aroma of vanilla, t o which t h e flavor is attributed, does not preexist in the beans but is formed by a chemical reaction induced during the drying or curing process t o which t h e beans are subjected after harvesting. Behrens2 states t h a t ripe vanilla beans have little or no odor but become strong in odor by curing,
C O Y I B R C I A L VANILLABBANS
due t o the splitting up of a n existing glucoside with the formation of t h e compound vanillin. The above statement regarding t h e odor of vanilla was confirmed by Busse: who states t h a t vanillin is formed from a nonodorous body partaking of t h e nature of a glucoside. In a n extensive research with vanilla, Lecomte' found t h a t the fruit of vanilla contained, besides the glucoside coniferin, two ferments, one an oxidase and t h e other a hydrolyzing agent. The latter conUnited s t a t ~ Pharmacopoeia. ~ Eishfh Decennial Revision. 1900, +97. "Ueber dap Vorkommen des Vanillins in der vmille." Der Tio9cnpllonarr, 3 (1899). 299. 1 W. Bur& "VanillcChemie der vanille Prueht. Arbeiten ~ U Bdem Kaiserliehen Gcsundheitnarnte," Berlin. XV. 1898 bir 1899, p . 101. a H. Lccomte. "Sur la formation du parfurn de la vanille." Cornpi. vend.. I33 (1901). 745. %
e J. Behren.,
