IOWA STATE COLLEGE JOURNAL OF SCIENCE Published on the first day of October, January, April, and July EDITORIAL BOARD EDITOR-IN-CHIEF, Joseph c. Gilman. AssISTANT EDITOR, H. E. Ingle. CONSULTING EDITORS: R. E. Buchanan, C. J. Drake, I. E. Melhus, E. A. Benbrook, P. Mabel Nelson, V. E. Nelson, C. H. Brown, Jay W. Woodrow. From Sigma Xi: E. W. Lindstrom, D. L. Holl, B. W. Hammer. All manuscripts submitted should be addressed to J. C. Gilman, Botany Hall, Iowa State College, Ames, Iowa. All remittances should be addressed to Collegiate Press, Inc., Iowa State College, Ames, Iowa. Single Copies: One Dollar. Annual Subscription: Three Dollars; in Can­ ada, Three Dollars and Twenty-Five Cents; Foreign, Three Dollars and Fifty Cents. Entered as second-class .:me«Eir '~~~ 1~;. :t935.- Qt. the postoffice at Ames, Iowa, under the,..... ae,t . .df. ?,JEO:'cn 3, 11119.: :. .',: . .:. .: ..: ... .. .... .... .. ... .. .. : .. ·... ···.. ·.. · .. ::·::··.. .. ·. .. .. ·: . .· .: .. .. .. :. ·.... · .. .. :. : : .: : . .. : .. ·: .: ·. ..·... ··::.:: .. : ·:·.·.: ....... THE EFFECT OF SODIUM THIOSULFATE AND SODIUM HYDROGEN SULFITE ON SOME SILKS1 RUTH L. JOHNSON, MINNIE E. LICHTE, AND RACHEL EDGAR From the SectiO'nS of Home Economics (Textiles and Clothing) and Chemistry, Iowa Agricultural Experiment Station Received September 24, 1941 Sodium thiosulfate has been used for the preservation of weighted silks (5, 7) and sodium hydrogen sulfite for the bleaching of silk, the removal of dyes or manganese dioxide from silk, the weighting of silk (2, 10), the preservation of weighted silk (12, 13, 14, 15, and 16) , and the printing of dyes on silk (3, 9). Procedures for such treatments, however, occur in the literature without further description of the effect these compounds have on silks. Quantitative data for the effect of sodium thiosulfate and sodium hydrogen sulfite on some silks are reported in this study. Wild-silk fibroin, silk fibroin, and iron-weighted, lead-weighted, tin-weighted, tin­ lead-weighted, and zinc-weighted silks have been analyzed as to weight, ash, nitrogen, and wet strength after 10 hours at 40°C. in 50 volumes of N sodium thiosulfate; the unweighted silks have been examined after 10-hour immersion in 50-volume baths of 1.9232 N sodium hydrogen sul­ fite followed by 1 hour's steaming at 123.9°C. These two silks have also been tested for wet strength after 1 hour at 100°C. in 50-volume baths of 0.0500 to 2.0000 N sodium hydrogen sulfite. EXPERIMENTAL PROCEDURE The plain-woven silks, described in Table 1 and elsewhere (8), were cut for analysis and the samples were separately treated for 10 hours with 50 volumes of water or N sodium thiosulfate in stoppered 500-milliliter Erlenmeyer flasks in a water bath at 40 ± 0.1 °C. and washed with water until the rinse no longer decolorized permanganate. The two unweighted silks were immersed separately for 10 hours in 50-volume baths of water or 1.9232 N sodium hydrogen sulfite at 40 + 0.1 °C., drained, steamed for 1 hour at 123.9°C., and rinsed with water as described before. Four 4-gram samples of a fabric or five 1-inch strips of it were steamed at a time in an autoclave equipped with pressure gauge and thermometer; the samples were hung by silk thread from glass rods laid across the top of a 4-liter Pyrex beaker having a low outlet for steam and were protected by an inverted watch glass from any liquid which had flowed across metal. Ten 1-inch strips of an unweighted silk were refluxed on a boiling water bath in 50 volumes of water or sodium hydrogen sulfite for 1 hour 1 Journal Paper No. J-933 of the Iowa Agricultural Experiment Station, Ames, Iowa. Project 262. [411] TABLE 1 ANALYSIS OP SILK FABRICS ELONGATION OP FABRIC AT BREAKING STRENGTH OF FABRIC BREAKING LOAD WEIGHT THICKNESS OF FABRIC OF FABRIC Conditioned Wet Conditioned Wet SILK Warp Filling Warp Filling Warp Filling Warp Filling Percentage Percentage Ounces per Pounds Pounds Percent- Percent- Percent- Percent- Square Yard 0.001 Inch per Inch per Inch of Condi- of Condi- age age age tioned tioned age A. Iron-weighted ..... ... 3.00 (0.01) * 6.6 (0.1) 34 (1) 12 (O) 97 75 10 7 25 34 B. Lead-weighted ...... .. 3.17 (0.02) 6.5 (0.2) 30 (O) 12 (1) 57 58 7 7 16 23 c. Tin-weighted .. .... 2.86 (0.01) 6.3 (0.3) 38 (1) 13 (1) 53 46 10 9 35 23 D. Tin-lead-weighted ... 3.15 (0.02) 6.5 (0.2) 42 (O) 13 (1) 57 46 10 7 35 28 E. Zinc-weighted ........ 2.86 (0.01) 6.2 (0.2) 40 (O) 14 (0) 58 50 10 8 35 31 F. Fibroin . ........ ... 2.20 (0.03) 6.7 (0.2) 38 (1) 32 (0) 92 81 34 37 56 55 G. Wild fibroin .. ... ..... 1.25 (0.01) 4.2 (0.3) 21 (0) 23 (1) 81 43 30 30 38 37 *Mean deviations are within parentheses. TABLE !-(Continued) DISTRIBUTION OF YARNS IN FABRIC YARN NUMBER TwisTt By Number By Weight SILK ! Warp Filling Warp Filling Warp Filling Filling Number Number Percentage Percentage Number Per Inch Per Inch of Fabric of Fabric Typp Typp Per Inch A. Iron-weighted . ..... ..... .. 160 (O) * 74 (O) 69.0 (0.2) 31.1 (0.2) 48.7 (0.3) 46.9 (0.3) 62 (2) B. Lead-weighted ............ 127 (1) 74 (O) 60.6 (0.2) 37.8 (0.1 ) 37.4 (0.4) 44.8 (0.2) 31 (2) c. Tin-weighted ........ ...... 155 (1) 72 (1) 65.1 (0.6) 34.9 (0.6) 44.8 (0.6) 44.8 (0.0) 75 (5) D. Tin-lead-weighted . ... .. 180 (1) 79 (1) 71.4 (0.1) . 28.5 (0.2) 45.4 (0.3) 48.5 (0.5) 84 (4) E . Zinc-weighted ..... 170 (0) 70 (1) 73.0 (0.9) 26.0 (1.1) 51.9 (0.4) 48.5 (O.O) 62 (3) F. Fibroin ...... .... ... .. .... 246 (2) 109 (1) 59.0 (0.5) 40.3 (0.3) 127.8 (1.8) 88.2 (0.1) 60 (2) G. Wild fibroin . ............ 76 (1) 77 (1) 45.3 (0.7) 53.7 (0.7) 71.7 (0.6) 78.0 (0.5) 1 *Mean deviations are within parentheses. tTwo S-twisted crepe yarns alternate with two Z-twisted crepe yarns the length of the fabric; the multifilament yarns of the warp and of the wild fibroin are not measurably twisted. TABLE 1 ANALYSIS OF SILK FABRICS (continued) ASH WEIGHTING WATER EXTRACT SILK Fabric Warp Filling Percentage Percentage Percentage Percentage Percentage of Fabric of Yarn of Yarn of Fabric of Fabric A. Iron-weighted . ... .. ... ............ 43.70 (0.00) * 42.51 (0.07) 40.23 (0.22) 70.6 (0.7) 10.9 (0.3) B. Lead-weighted . ............... ... 44.16 (0.03) 44.49 (0.28) 44.55 (0.10) 55.3 (0.3) 8.8 (0.5) c. Tin-weighted .. ........ ... ... .. 52.87 (0.02) 54.22 (0.07) 52.93 (0.04) 61.3 (0.1) 7.2 (0.4) D. Tin-lead-weighted ... .... .. .. .... 50.27 (0.06) 52.63 (0.12) 48.72 (0.00) 60.8 (0.6) 4.4 (0.6) E. Zinc-weighted . .. .......... .. ...... 51.93 (0.08) 53.68 (0.07) 49.93 (0.07) 63.5 (0.4) 4.6 (1.5) F. Fibroin .. .. ... .......... .. .. 0.30 (0.03) . .. ....... ..... .. ..... .... .. .. G. Wild fibroin .... ..... .. ...... .. ... 0.60 (0.01) . .. ............. .. *Mean deviations are within parentheses. TABLE 1-(Continued) ALUMINUM IRON LEAD NITROGEN PHOSPHORUS SILIGA TIN ZINC SILK Percentage Percentage Percentage Percentage Percentage Percentage Percentage Percentage of Fabric of Fabric of Fabric of Fabric of Fabric of Fabric of Fabric of Fabric A. Iron-weighted . ..... .. .. 15.11 (0.02)* . 8.16 (0.03) 0.56 (0.00) 12.52 (0.02) . ........... B. Lead-weighted .... .... trace ........ ... 12.21 (0.04) 9.17 (0.05) 0.91 (0.01) 20.30 (0.06) . ... .. ...... c. Tin-weighted ...... ..... 9.26 (0.04) 0.45 (0.01) 20.49 (0.07) 8.80 (0.05) . ...... .. .. D. Tin-lead-weighted ... .. ... trace ... ......... 9.10 (0.03) 8.46 (0.04) 1.06 (0.00) 14.91 (0.08) 8.66 (0.06) . E. Zinc-weighted ...... .... 0.85 (0.02) .. ......... 8.10 (0.07) 0.57 (0.00) 15.07 (0.06) . 11.12 (0.02) F. Fibroin ................ .. 18.59 (0.02) . ........ .. G. Wild fibroin ............. .. .. 18.25 (0.00) . ........... ........... *Mean deviations are within parentheses. TABLE 2 EFFECT oF F1FTY VoLuMEs oF SomuM TmosuLFATE IN TEN HouRs AT 40°C. oN THE WEIGHT, AsH, N1TR.OGEN, AND WET STR.ENGTH OF THE SILK FABRICS SODIUM BREAKING WEIGHT ASH NITROGEN THIOSULFATE STRENGTH OF SILK WET WARP Percentage Percentage Percentage Pounds Normality of Fabric of Fabric of Fabric Per Inch A. Iron-weighted ....... ... ... : .. .. .. .... 0 96.5 (0.1) * 40.23 (0.07) 8.08 (0.03) 32 (2) 1 108.7 (0.0) 50.58 (0.17) 8.05 (0.02) 31 (1) B. Lead-weighted . .. ... ....... .. .. .. ...... 0 93.0 (0.1) 44.07 (0.07) 9.08 (0.03) 20 (1) 1 101.6 (0.1) 44.17 (0.08) 9.04 (0.01 ) 19 (O) c. Tin-weighted ... .. ...................... 0 93.1 (0.3) 51.35 (0.31) 8.64 (0.05) 24 (0) 1 99.2 (0.1) 48.60 (0.07) 8.59 (0.05) 20 (O) D. Tin-lead-weighted ....... ........... .... 0 96.0 (0.1) 49.04 (0.08) 8.50 (0.04) 21 (1) 1 102.2 (0.1) 53.45 (0.10) 8.33 (0.01 ) 18 (2) E. Zinc-weighted .. ..... .... ...... .. 0 96.0 (0.1) 50.06 (0.31) 7.79 (0.02) 21 (1) .