August 1951
I N D U S T R I A L AN.D E N G I N E E R I N G C H E M I S T R Y
1821
one side t o allow visual inspection of the clearance between the male fitting and the glass tube. Figure 2 shows the disassembled and assembled views of a typical fitting. The dimensions and details of construction may be varied considerably from those shown in Figure 1 depending on the requirements. For example, it might be desirable t o use a split supporting ring rather than the solid one shown, should i t be inconvenient to put this ring in place on the glass before forming the upset shoulder. Other methods can be used to compress the O-ring gasket against the end of the glass. Although one set screw on the support ring proved t o be amply strong, three set screws would provide added strength. Since it was desired to minimize the amount of free volume within t h e fitting itself, the fitting was not constructed according to the standard Army-Navy (A/N? specifications. If the amount'of the free volume within the closure is not critical, the closure can be constructed according t o the standard specifications. The cut-away portion on one side of the female fitting is not necessary unless visual inspection of the clearance is desired. This closure has been used only at room temperature, but the use of O-rings of special materials such as silicone rubber or Teflon would extend the range. For example, Linear, Inc., Philadelphia, Pa., offers O-rings made of silicone rubber for use at temperatures ranging from -65' to 400' F. This closure should be suitable for making pressure-tight joints between a metal and brittle materials such as glass or ceramics which can be formed by heating and/or grinding. LITERATURE CITED
Figure 2.
Disassembled (Left) and Assembled (Right) View of aTypical Seal
(1) Onnes and Braak, Comm. Univ. of Leyden, No. 166 (1923). RECEIVED Deoember 12, 1950.
Solubility of Methyl Bromide in Water and in Some Fruit Juices GILBERT P. HAIGHT, JR.' Bureau of Entomology and Plant Quarantine, United States Department of Agriculture, Honolulu, T . H. Absorption of methyl bromide, a fumigant, by fruit is of prime concern in insect control. Preliminary experiments showed large absorption by juices. No reliable value for the solubility of methyl bromide in water was found in the literature. As this is a fundamental property of methyl bromide, a determination was made, so the value would be available in the future for those using this material. The solubility of methyl bromide is greater in water than in the juice of pineapples, mangos, and papayas under comparable conditions.
I
THE course of studies on the effect of methyl bromide fumigation on larvae of the oriental fruit fly ( D a m s dorsalis Hendel) found in Hawaiian fruits, the question arose as t o whether absorption by the fruit might hinder penetration and thus account for low kills. As a preliminary test, methyl bromide gas was bubbled through the juice and found t o be absorbed in quantities in excess of 1 ml. of gas per ml. of juice. As the literature contains very little information on the solubility of methyl broIrj
1 Present address, Chemistry Department, George Washington University, Washington, D. C.
mide in aqueous solutions, it was decided to measure the solubility in water as well as in various juices for purposes of comparison. Lepigre ( 1 ) gives the solubility of methyl bromide as 5 t o 10 grams per liter of water at 18"C. Shepard ( 2 )gives the value 0.1 gram per 100 grams of water, with no experimental evidence or conditions. MATERIALS, APPARATUS, AND PROCEDURE
Distilled water and freshly obtained filtered fruit juices from ripe fruits were used throughout. T h e juices tested were: Fruit Pineapple Mango Papaya
PH 3.5 4
5
Density, G./Ml. 1.051 1.035
1.027
Technical grade liquid methyl bromide was used as the source of methyl bromide gas. The apparatus consisted simply of three traps in series, as illustrated in Figure 1. T h e first contained methyl bromide liquid, the second water, and the,third a weighed sample of the solvent being studied. The second and third traps were placed in a water bath to regulate the temperature. The first was kept
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I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
in an ice bath, except when methyl bromide gas was needed; then it was simply exposed t o the temperature of the room, whereupon the liquid boiled freely. Bubbling through the traps was continued until the trap containing the sample solvent attained constant weight. Correction was made for displacement of air by methyl bromide in the trap, absorption of methyl bromide by rubber policemen used to close the trap during weighings, and water vapor in the trap. In tests of mango juice it was also necessary to correct for measurable loss in lveight due to fermentation of the juice during the course of each test.
Vol. 43, No. 8
TABLE I. SOLUBILITY DATA Sample 1
2 3
Wt. of Water, G. 4.99 19.74 11.09
Vol. of Gas, PIl. 13.86 19.10 27.75
Correction for Change in Wt. of Gas, G. 0,0389 0.0537 0,0781
Increase in Wt. of Policeman, G. 0.0000 0.0019 0.0000
1 0
3
Correction for Vapor Pressure, MI. 0.42 0.57 0.83
Total Increase in Wt., G 0.3742 0.3197 0,2272
Increase in W t . of S o h . ,
of Methyl
G.
0.3353 0.2641 0.1491
Solubility
Bromide G./100 d. 1.341 1.341 1.342
EXPERIMEhTA L RESULTS
Results a t different temperatures were checked by using different amounts of solvent, so that corrections of different magnitudes were necessary. Methyl bromide weighs 0.0029 gram per ml. more than air at standard temperature and pressure. A typical set of data for 11 ater a t 25 C. is given in Tahlc I. O
TABLE 11. SOLUBILITY OF METHYL BROMIDE IN WATERA FRUIT JUICES Temp.,
Solvent TVater
Q
c.
10 :1 2.5 32
Pineapple juice
:= 6 m m .
Figure 1. Apparatus for Determining Solubility of Methyl Bromide in Water a i d Fruit Juices
The results a t this temperature, which approximates room temperature, were the most consistent. The solubility data for water and the various fruit juices are given in Table 11.
Mango juice Papaya juice
Correction In the article entitled “Vapor Phase Condensation of Aniline to Diphenylamine” by Hoelscher and Chamberlain [IND.ENG. CHEM.,42, 1568 (1950)], the authors wish to correct the equation relating the entropy of gaseous diphenylamine to temperature and the subsequent equation giving the variation of the entropy change of the reaction with temperature. Further study into the methods available for estimating the heat capacity-temperature relationship for gaseous diphenylamine, as well as the value of the entropy a t 298” I
