Detection of Second-Hand Kapok In Articles of Bedding and Upholstered Furniture C. 11. JEPIICO’IT ARD W. 11. 11. BISHOP Department of Health of Ontario, Toronto, Canada
One hundred samples of kapok, consisting of 41 samples of new material and 59 samples of secondhand material, were tested in order to establish a method for detecting the presence of second-hand material. The grade of a sample was jndgecl both by \isual inspection to detect signs of general disintegration of the fibers and by the intensity of the fluorescence exhibited under ultraviolet light. Determinations were made of ammonia, urea, sodium sulfate, sodium chloride, pII of the aqueous extract, and oil and fat content. Experiments were performed to determine the specific buo>ancy and the
T
HD;Ilcdding regulations of tlic Departmint of 1Icaltli
of
Ontario came into force on December 28, 1938. These rcgulations statc, in part, t,hat every mattress, bolster, and feather h t l and every article of upholstered furniture shall be labeled and the label shall give the name and address of the manufacturer, when ne!\- materials are used exclusively the article shall he labeled “contains new material only” 011 a white label, whore “secondhand” materials are used in part or i n whole the article shall be labeled “contains second-hand material” on a yellow label. A suitable method for the detection of second-hand material mixed or uriinixed with new material i p of importancc in the atiministration of these regulations. il considerable amount of experiniental work lias been donc on the various kinds of kapok and kapoklike fillers, niainly with the object of ascertaining t,heir suitability for commercial purposes or of detecting adulteration by other fibers. The various tests which have been suggested for the detection of the presence of second-hand kapok may be divided into tv-o groups: those showing alteration in the material itself-visual inspection, change in fluorescencc, loss of buoyancy, etc.-and those based on the increase or decwase in the relative concentration of different constituents prescsiit i l l kapolc--c.g., amnioiiiurn salts, urea, sulfates, pentosans, n-as, ash, ete. I n 1936, lIoskowitz, Landes, and Himmelfarb (2) of the Redding Division, Sei\- Tork Stat,e Department of Labor, in a paper on the detection of second-hand kapok stated that a sample should be designated as s c ~ o ~ i d - h a nif dthe urea or ammonia coiitent or both n-ere great,er than 0.015 and 0.030%, respectively. They pointed out that a partial separation of a mixture of nely and second-hand kapok can lie made by the difference in fluorescence exhibited urider ultraviolet light. hlthough nodata \\-erepresented, they reported that the results of their tests on the wax and ash content and of the buoyancy of nen- and second-hand kapok were overlapping and that these methods n-ere unsuitable as a means of differentiating betweon n c ~ vand sccond-hand material. As the information on the dctectiori of second-hand kapok published to date is somen-hat meager, arid the subject should be of interest to others responsible for the adriiinistrrttion of bedding regulations, further experimental n-ork in this field n-ns indicated. The present paper deals with the results of the analyses of 100 samples of new and second-hand kapok. I n this connection the word “kapok’] includes both true kapok and kapoklike materials used by the trade. Eighty-two of the samples were collected either by the authors or by a bedding inspector. Of these, 59 were samples of second-hand material obtained from used mat519
percentage loss of buo?anc? in 96 hours. The urea, sodium chloride, oil and fat, and buoj ancy tests were found of little value and were discarded. The ammonia, sodium sulfate, and plI determinations were found of practical application and standards were adopted: 0.036570 for the ammonia content, 0.3657‘ for the sodium sulfate content, and 5.15 for the pII value. I t is considered by the authors that a sample of kapok contains second-hand material when the grade is 5 or less and the ammonia content exceeds 0.036570 and either the sodium sulfate content exceeds 0.365q0or the pH value is less than 5.15 or both. trt:sses or bales of second-liaiid kapok ; ~ r i C i33 \\-ere sample> oi rieir kapok obtained locally from wholesalers and supply houses. Eighteen additional samples of new kapok were procured through the kindness and cooperation of the Bedding Division of the S e w York State Department of Labor. Information concerning the geographic source of all the ncw samples was ol~taiiieda t the time of collection. SIETHODS
Determination of Grade. In determining the grade of a sample, two properties n-ere assessed: t.he physical condition of the material arid the intensity of the violet fluoresccnca eshibited under ultraviolet, light. The condition was judged by visual inspection and the following factors were taken into consideration: length of fiber, presence of matted, curled, or broken fibers, and general signs of disintegration. .2value of 0 was given to samples that had become completely powdered, whereas samples that appeared to be the best material were given a value of 4. l‘alues of 1, 2, or 3 were given to samples that warranted intermediate ratings. Fivr samples, one for each of the values, were kept as reference standards and the condition of a sample to be tested was judged by comparison with these standards. The equipment used for determining the fluorescence consisted of a 400-watt Hanovia analytic model quartz mercury vapor lamp installed in a dark room. The lamp was fitted with a red-purple Corex A No. 986 molded and polished glass filter 3 mm. thick. Willsonite goggles (shade C) were used as an eye protection and also as an aid in accentuating the differences in appearance of the fluorescence under ultraviolet light. A value of 4 was given to samples that exhibited a deep violet fluorescence. Values 3, 2, or 1 Tvere given t,o samples that showed progressively decreasing amounts of violet fluorescence, and a value of 0 was given to samples that exhibited no violet fluorescence. Five samples, one for each value, were kept as reference standards and the intensity of the violet fluorescence of a sample to be tested was judged by comparison with these standards. I t was found that ‘the fluorescence of kapok decreases on exposure to ultraviolet light,. Thus the length of time of exposure must be kept to a minimum. The intensity of the violet fluorescence is difficult t o assess, as it is a surface phenomenon and the authors have adopted the technique of orienting the sample in such a way as to present a level surface a t right angles to the rays. The new or second-hand nature of lrapoli cannot be tleteriiiined by either the condition only or the fluorescence only, as there is an
overlapping bet,ween the poorer types of new material and the best types of second-hand material. However, the two properties used together removc this difficulty. The grade, as used in this paper, is the sum of the value for the condition and the value for the fluorescence. Thus a sample with a maximum value for
ANALYTICAL CHEMISTRY
520 condition of 4 and a maximum value for fluorescence of 4 would have a grade of 8, and a sample with a minimum value for condition of 0 and a minimum value for fluorescence of 0 would have a grade of 0. All other samples would have an intermediate grade ranging from 1 to 7. Ammonia, Urea, Sulfate, and Chloride Detemhnations. The methods used have been described ( 1 ) . pH Determination. Two and one half grams of kapok art? immersed in 75 ml. of distilled water and kneaded with a thick glass rod until thoroughly wetted. After standing overnight, the kapok is kneaded again and the solution expressed. The hydrogen ion concentration of this aqueous extract is determined to the nearest 0.1 pH by means of a Coleman Model 3 8 p H electrometer. Oil and Fat Determination. Five grams of kapok are immersed in 200 ml. of carbon tetrachloride in a 500-ml. Erlenmeyer flask. The flask is fitted with a reflux condenser and the contents are boiled for 1.5 hours. After cooling, the carbon tetrachloride is filtered off by suction and the kapok yashed with a small amount of carbon tetrachloride. The filtrate is transferred to a distilling flask and the solution concentrated to about 10 ml. The concentrate is transferred to a weighed platinum dish and the carbon tetrachloride evaporated off on a hot plate. The dish is cooled in a desiccator and weighed. The residue is reported as the oil and fat content. Buoyancy Test. The equipment consisted of a copper wiremcsh cage measuring 5 em. ( 2 inches) long, 5 cm. (2 inches) nide, and 6.25 em. (2.5 inches) deep fitted witha wire-mesh lid. The cage was filled t,o a depth of 1.25 em. (0.5 inch) with lead shot and glass beads. Thus the cage formed a hollow cube, 131 cc. (8 cubic inches) in volume. As the specific buoyancy depends in part on the weight of kapok per unit volume, the uniformity of the packing, the temperature of the water, and the length of time immersed, experimental work was done to determine the optimum conditions for carrying .~ out the test. The following procedure was finally adopted. The weighted cage was suspended from the left arm of the balance (left oan removed), immersed in a 600-ml. beaker filled with distilled kater a t room’temperature (previously boiled to remove dissolved air), and weighed (A). The cage was removed, carefully packed with 4 grams of kapok, slowly immersed so as to assure the release of the entrapped air, and reweighed ( B ) . The immersion was continued for 96 hours, after which the cage was again weighed (C). A - B Calculation. Initial specific buoyancy = ___
4
Percentage loss of buoyancy = (A - B )
-
(A
(B - B )
- C)
Buoyancy factor = initial specific buoyancy divided by percentage loss of buoyancy
Table 1. of
5 11 25 8 16 11 9 7 8
Grade 8 7 6 5 4 3 2 1 0
of Samples 3
11 25
(;rade 8 7 6
5 4 3
8 16 11 9 7 8
Highest 0.001 0.004
0.008
0.004 0.015 0.021 0.017 0.025 0.030
2 1 0
Urea Found, S; Average
0.000 0.002 0.001 0.002 0.003 0.006 0.005 0 . 006 0.010
IJzzt 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
~
Table 111.
Sodium Sulfate Content of Kapok
No.
of Samples 5 11 25
Grade 8 7 6
8
5 4 3
16 11
Sodium Sulfate Found, 70 Highest .iverage Lowest‘ 0.16 0.52 0.51 1.19 1.11 0.99
0.10 0.26 0.21 0.44 0.52 0.61
0.05 O.OR
0.03 0.12 0.20 0.20
the grade is accompanied by an increase in the concentration of sodium sulfate. In Table IV are shown the results of the chloride determinations calculated as sodium chloride. There is a aide variation in the amounts found, especially in the samples in grades 6 to 8. A summary of the pH values of the aqueous extracts is found i n Table T. There is a distinct difference in the average values found in samples in grades 6 to 8 from those found in samples in grades 0 to 5 . Table VI gives the results of the oil and fat determinations, There is a small differencebetween the average percentage found in samples in grades 6 to 8 and those found in samples in grades 0 to 5 but this difference is not significant The results of the buoyancy experiments are shown in Table VII. .Is the value of the grade decreases, there is a gradual decrease in the average initial specific buoyancy and in the average buoyancy factor and ti gradual increase in the average percentage loss of buoyancy. However, there is a !vide variation in the results among the samples in the same grades.
.
.&mrnoniaContent of Kapok
so. Samples
Table 11. Urea Content of kapok so.
Highest
Ammonia Found, Average
0.015 0.036 0.031 0.092 0.223 0.211 0.147 0.164 0.215
0.007 0.018 0.015 0.049 0.054 0.101 0.093 0,109 0.129
7’ Lowesi 0.003 0.001 0.003 0.024 0.020 0.038 0,040 0.069 0.060
Table IV.
Sodium Chloride Content of Kapok
NO.
of
Samples
Grade
5 11 25 8 16 11 9 7 8
8 7 6 J
4 3 2 1 0
Sodium Chloride Found, % Highest dverage Lowest
0.05 0.50
0.63 0.09 0.11 0.16 0.17 0.32 0.29
0.03 0.10 0.15 0.07 0.06 0.08 0.07 0.11 0.09
0.01 0.02 0.04
0.02 0.02 0.02 0.02 0.04 0.02
RESULTS
The results of the ammonia determinations, summarized in Table I, include the highest, average, and lowest percentages for each of the nine grades. It is seen that the concentration of ammonia, on the average, increases as the value of the grade decreases. Table I1 gives the results of the urea determinations. The urea content, on the average, rises very gradually as the value of the grade decreases. However, one or more samples in each grade showed no detectable amounts of urea. The sulfate determinations, reported as sodium sulfate, are shown in Tahle 111. On the average, a decrease in the value of
Table V. pH Value of Solutions of Kapok so.
of Samples J
Grade
8
11 25
7 6
8 16 11
5 4 3 2
9,
1
0
Highest 5.6 6.7 7.1 5.0 5.6 5.4 5 3 5 0 5 8
p H Value Found Average . 5.4 5.5 5.7 4.8 4.9 4.8 4.8 4.8 5 0
Lowest 5.3 5.2 5,l 4 4 4.5 4 4 4 .i 4 3 4 6
V O L U M E 21, NO. 4, A P R I L 1 9 4 9
521
grade gives a very good indication of the new or secondhand nature of the sample. The better quality of second-hand NO. kapok used again by the trade to make mattresses, etc., had B Of -- Oil a n d Fat Found, Qc Samples Grade Highest Average Lowest grade of 3 , 4 , or 5. Samples which grade as 0, 1, or 2 are of such 5 8 0.53 0.47 0.41 poor quality that they are of no use to the bedding and upholster11 7 0.58 0.50 0.41 25 6 0.72 0.56 0.41 ing industry. 8 3 0.76 0.64 0.51 Tests. An ideal t,est to distinguish between a sample of new 16 4 0.82 0.62 0.47 and of second-hand kapok would fulfill the following conditions: 11 3 0.94 0.68 0.49 The results for netv kapok would altvays be negative and the re0.48 9 2 0.97 0.65 7 1 0.86 0.69 0.55 sults for second-hand kapok 0.77 0.67 0.58 8 0 would always be positive mid ~. sufficiently high to make the Table VII. Buoyancy of Different Grades of Kapok evidence conclusive. Unfor% LOSSof Buoyancy in 96 tunately, none of the methods No. of Initial Sperific Buoyancy Hours Buoyancy Factor available meets the first reSamples Grade Highest -4verage Lowest Smallest Average Greatesi Greatest .Iverage Smallest quirement. In assessing the 28.3 11.1 31.2 29.9 13.4 16.9 5 8 2.29 1.67 2.79 11 7 32.5 29.1 25.2 13.1 22.4 29.0 2.15 1.36 1.05 relat'ive merits of the tests re25.7 9.3 24.7 33.7 31.9 29.0 25 6 3.13 1.29 0.78 ported in this paper, it is evi27.9 15.3 23.7 30.3 28.7 29.1 1.98 8 5 1.25 0.98 dent that they are not of equal 16 4 30.3 28.1 24.1 15.3 24.3 32.0 1.86 1.22 0.80 11 3 29.6 27.5 24.2 17.1 27.8 34.5 1.67 1.02 0.74 value. 23.0 24.6 19.9 28.6 29.1 36.6 9 3 1.24 0.87 0.54 CHEMICAL TEST. Anzamnia 19.5 17.8 26.2 33.6 57.7 0.78 0.62 0.33 7 1 21.5 8 0 24.0 19.9 17.1 26.8 27.9 29.4 0.85 0.72 0.58 Determination. The authors consider that the ammonia determination is the best of the chemical methods which DISCUSSION were investigated, as it most closely approaches the ideal conditions mentioned above. I t will be seen from Figure I that, Selection-of Samples. The 100 samples of kapok used in this as the value of the grade decreases, there is, on the average, investigation were selected with a definite object in view. an initial gradual rise followed by a sharper rise in the concentras o as to be able to test as wide a variety of samples of new tion of ammonia. The highest amount of amnionla found i n the kapok as possible, it was considered necessary to include samples samples of grades 6 to 8 n-as 0.036% (Table I). This led to the from all the geographic sources from rrhich manufacturers might adoption of 0.0365% as the standard for the ammonia determinaobtain such material for use in the bedding and upholstering intion, as the figure is just, above the amount found in any sample of dustry. Further efforts were made to obtain different commercial new kapok which was tested. This standard is in close agreement grades of new kapok from each geographic source. Pertinent with that proposed by Moskowitz et al. information concerning the origin of the samples was obtained As shown in Table IX, where the grades have been grouped, all from the supply houses a t the time of collection. The 41 samples the 41 samples in grades 6 to 8 had substandard concentrations of of new kapok reported to be from each of the ten geographic ammonia, whereas 30 out of 35 or 85.7% of the samples in grades sources are shown in Table VIII, and the average values of the 3 to 5 and all the samples in grades 0 t,o 2 had an ammonia content results of the different determinations are shomn for comparative in excess of 0.0365%. purposes. Information concerning one sample seemed to be Sodium Sulfate DetelniirLation. Of somewhat less value is the doubtful and its source is recorded as unknown. sodium sulfate determination. As shown in Figure 2, as the value The remaining 59 samples were obtained by the authors or a of the grade decreases there is, on the average, a fairly sharp rise bedding inspector from mattresses or bales of second-hand kapok. Care \I ath taken to collect all types of second-hand materid from in the conccntration of wtiium sulfate. The highest, amount the very best to the very poorest quality Although it ~-was realized that only thcb Table VIII. Analyses of New Kapok from Different Geographical Sources better quality of second-hand kapok is re-used by the beddverage Values - ~_____ No. Range Sodium Sodium Oil and ding and upholstering indusGeographical of of .iinmonia, Urea. sulfate, chloride, pH Buoyancy fat, try, it was considered a d v i s Samples Grades Source factor yc sc 7 value Qc % able to include as wide a range 11 Dutch East Indie. 8-6 0,010 0.11 0.001 0.04 6 , 5 0.48 1.69 2 Indo-China 7-6 0.32 0.018 0.001 0.46 1.29 0.08 5.5 of second-hand material as .5 India 7-6 0.009 0.21 0.002 0.18 1.30 n.58 6.2 1 6 Thailand 0.029 0.35 0.001 1.45 5.6 0.06 possible for the sake of com4 Philippinca 0,020 7-6 0.22 0.003 0.09 0.46 3 ,3 1.15 7 pleteness. 6 Ecuador 0.013 0.20 0.001 0.06 0.60 1.11 6.0 4 7-6 Brazil 0.015 0.20 0.002 5 . 3 0.57 0 . 6 2 0.92 Grading of Samples. Each 1 6 Peru 0.031 0.51 0.000 ... ... 1.30 1 Mexico 6 0,029 0.36 0.001 .5 , 3 2.41 0.04 ... sample of kapok was graded 4 7-6 Africa 0.022 0.31 0.001 5 .3 0.05 1.34 0.44 6 1 Unknown 0.015 0.12 0.000 5.6 0.62 0.96 0.05 according to a combination of two factors: the physical con_ _ ~ ___ ~ . ~ ____ _ _ dition of the material and the Table IX. Number and Percentage of Samples of Kapok above and below Standards intensity of the violet fluores Ammonia Sodium Sulfate PH cence exhibited under ultraBelow Above Below Above Above Below violet light. 0.0365% 0.0365% 0.365% 0.365y0 5.15 5.15 No. of % of No. of % of No. of % of No. of % of N o . of % of S o . of % of All the 41 samples of new aamSamSam>am- SamSamSamSamSamsamzamYamNo. of kapok had a grade of 6, 7, or Samples Grades ples plea ples yles plea ples des des ples des des des 8 ; all samples of second-hand 41 6, 7 , 8 100 0 0 38 93 3 7 40 98 1 2 35 3,4, 5 14 30 86 31 24 69 2 6 33 . 94 kapok had a grade of 5 or 24 0,1,2 0 0 24 100 21 19 79 4 17 '20 83 less. Thus the value of the _______ Table VI.
Oil and Fat Content of Kapok
~
I
4i
':
.
.
ANALYTICAL CHEMISTRY
522
b
found in grades 6 to 8 was 0.527, aiid the lowest amount found in grades 0 to 5 was 0.12% (Table 111). It is possible that some kapok, before shipment to this continent, may be treated with hygroscopic sulfates or chlorides to prevent loss of moisture in transit; thus an occasional sample of kapok containing a relativelr high percentage of sulfates or chlorides might occur.
8
7
6
5
4
8
2
1
0
GRADE
Figure 2
.40
GRADE
I
Figure 1
A study of the. individual results led tu the adoption of 0.3G570 as the standard for the sodium sulfate determination. As shown in Table IS, 38 out of 41 or 92.7y0 of the samples in grades G t o 8 had substandard concentrations, whereas 24 out of 35 or 63.6% of the samples in grades 3 to 5 and 19 out of 24 or 79,2y0 of the samples in grades 0 to 2 had concentrations in excess of 0.365%. Sodium Chloride Determination. Ih Figure 1 is shown the average conccntration of sodium chloride for each grade of kapok. The average amount found in the samples of grade G is appreciably greater t,han the average amount found in the samples of any other grade. This is due to the relatively large quaiitit,ies present in new Brazilian kapok (Table VIII), possibly resulting from the additioii of a hygroscopic chloride. Furthermore, the average sodium chloride content of new Indian kapok is higher than the average amount found in second-hand material. For these reasons the determination of the sodium chloride contcnt was considered to be valueless. Urea Determination. The average urea coiitcnt of the samples in the different grades varied within narrow limits (Figure 1). Although some samples of second-hand kapok contained larger amounts of urea than was found in any sample of new kapok, there was a t least one sample of kapok in each grade which showed no detectable amount of urea by the method used. Thus the determination of urea is of limited value in differentiating between new and second-hand kapok. p H Determination. The average pH value of the aqueous extracts of the samples in each grade is s1ion.n in Figure 3. I t is apparent that there is a distinct difference i n the average pH values betn-een the samples in grades G to S and those in grades 0 to 5. In the samples in grades 6 to 8, the pH values range from 5.1 to 7.1 (Table V ) with the highest values, on the average, being found in the samples from India and Ecuador (Table VIII). In grades 0 t o 5 , the pH values range frbm 4.4 to 5.8. A study
2.80 2.40
t
'
\
I
1, 5.6
4
3.20
8
7
6
5
4
3
2
L
o
GRADE
Figure 3
of the individual results led to the adoption of 5.15 as the standard for the pH determination. Forty out of 41 samples in grades G to S had a pH value above 5.15, whereas 53 out of 59 samples in grades 0 to 5 had a p H value below 5.15 (Table I X ) . Oil and Fat Determination. The average concentration of material extractable by hot carbon tetrachloride for each grade of kapok is shown in Figure 2 (0 & F). I t is apparent that this test is of little practical value, as there is not sufficient variation in the average concentration in the different grades to be able to distinguish between the new and second-hand nature of a sample. BUOYANCY TEST. Figure 3 s h o w the average buoyancy factor (B.F.) for each grade of kapok. Generally speaking the lower
V O L U M E 21, NO. 4, A P R I L 1949 Table X. s o . of Samples
523
Classification of Samples of Kapok by Chemical Test (irade-
Y e w Ainterial , No. of '70 of samples sample-
Second-1Iand 1Iaterial s o , of '70 of sample*
iaml,les
0 80
a7
the grade, the lower the buoyancy factor. There is, however, in many cases such a wide variation between the individual samples in the same grade that the tcst is of lit,& value. Of the above determinations, the ammonia, sodium sulfate, and pH were retained while the urea, sodium chloride, oil and fat, and buoyancy were discarded. The standards adopted for the ammonia and sodium sulfate content were 0.0365 and 0.365%, respectively, while the standard chosen for the hydrogen ion concentration of the aqueous extract was 5.15. The number and thc'percentages of the samples v-hich had values below and above these standards are shown in Table IX. All the 41 samples of ne\v kapok (grades 6 to 8) had an ammonia content belon0.0365%, 38 had a sodium sulfate content below 0.365%, and 40 had a pH above 5.15. Of the 59 samples of second-hand kapok (grades 0 to 5 ) ,54 had an ammonia content above 0.036570, 43 had a sodium sulfate content almve 0.365%, mid 53 had a p l l below 5.15. Thus in differentiating between the new or second-haiicl nature of a sample of kapok, the ammonia determination has an over-all accuracy of 95%, the sodium sulfate determination an over-all accuracy of Slyo,and pFI determination an over-all accuracy of 93%. Moskowitz, Landes, and Hiniriiclfarb stated that a sample of kapok should be designated as second-hand if the urea or ammonia content or both are greater than 0.015 and 0.030%, respectively. They pointed out that if the urea mas found in amounts over 0.015%, the ainnionia was always higher than 0.03070 and thus t h e ammonia contcnt alont~is suficicrit t o
differentiate new from second-hand kapok. The results reported in this paper are in substantial agreement with this conclusion. It is, however, desirable to have additional evidence, and for this reason a sample of kapok is not considered, by the authors, t o contain second-hand material unless the ammonia content exceeds 0.0365% and either the sodium sulfate content exceeds 0.365% or the hydrogen ion concentration of the aqueous estract is below 5.15, or both. -4sample of new kapok, removed from it's own pod, had an ammonia content of 0.024% and a sodium sulfate content of 0.24%. ;Is the amount of kapok contained in the pod was insufficient, to do all the tosts, this sample was not included in the list of those reported. The samples of kapok classified as new or secontl-littiid according t o the above criterion are shown in Table S. The 41 samples i n grades 6 to 8 would all be classified as nviv. Of the 35 saniplcs in grades 3 to 5, which consist of the better type of second-hand kapok, 28 would be classified as second-hand and 7 would hc classified as new. These latter samples ivould be classified wrongly, mainly because of their having a substandard aninionia content. Of the 24 samples in grades 0 to 2, 21 would be classified as second-hand and 3 Ivould be classified as new. hlt,hough these latter samples had a high ammonia content, they did riot have either a sodium sulfate content in CSCCSR of 0.365% or a pH value below 5.15. ifying samples of kapok by means of this chemical test, no samples of new material would be classed as second-hand although, i n a fen- cases, second-hand samples would be classed as new. These errors are usually apparent when the sample is graded according to both the physical condition and the intensity of the violet fluorcwxnce eshihitcitl uiidcr ultraviolet light. LITERATURE CITED
(1) Jephcott, C. M.,and Bishop, W.H. I%.,1 x 0 . EN&.CHEX.,AXAL.
ED.,1 4 , 4 0 0 (1942).
(.7) Moskowitz, S., Landes, W.,and Himmelfaib, D , .4m. Dgestuf Reptr., 25, 220 (1936). R E C L LI D~ 4pril3, 1948
Electrolytic Determination of Copper In Brasses and Bronzes, Tin-Base Alloys, and Aluminum Alloys by Use of
Phosphoric Acid GEORGE XORWITZ. 577 7 7 t h S t . , Brooklyn 9 , By the use of phosphoric acid excellent results can be obtained in the electrodeposition of copper from brasses and bronzes containing tin. The sample is dissolved in 1 to 1 nitric acid without heating, phosphoric acid is added, and the solution is electrolyzed. To determine copper in tin-base alloys, phosphoric acid is added after solution of the sample in hydrochloric and nitric acids, and the solution is heated on the hot plate. The pyrophosphoric acid formed by heating is converted to phosphoric acid by boil-
T
HE use of phosphoric acid has given excellent results in the electrolytic determination of copper in brasses and bronzes, tin-base alloys, and aluminum alloys. COPPER IN BRASSES W D BRONZES
The use of hydrofluoric acid has been suggested by MeKay ( 5 )and Ravner (8)for the electrodeposition of copper from brasses
I%-.
Y.
ing with water, nitric acid is added, and the solution is electrolyzed. Copper is determined in aluminum alloys by dissolving the sample in an acid mixture of phosphoric, sulfuric, and nitric acids by heating strongly on the hot plate, adding water and nitric acid, and electrolyzing the solution. Silica is completely dissolved by the phosphoric and sulfuric acids and does not interfere. The method is not applicable to aluminum alloys containing tin, antimony, bismuth, or silver. and bronzes containing tin. Hydrofluoric acid, however, is an unpleasant reagent to handle, particularly when it must be accurately measured out, and the copper results are high unless the deposits are stripped from the cathode and replated ( 5 ) . Phosphoric acid, a reagent not subject to these objections, will give escelleiit results in electrolysis of copper from all t,ypes of brasses' and bronzes, including those containing tin. The method is simple and rapid.
