ANALYTICAL EDITION
MARCH 15, 1940 TABLE111.
scribed above, with those obtained by double dehydration of METHODSFOR DETERMISATION silica with hydrochloric acid followed by fusion of Rz03with SILICAA N D R203IN PORTLAXD CEMENT pyrosulfate to recover the residual silica; also with values NHdC1, ”4CI, obtained by dehydration with perchloric acid followed by pyResidual SiO: Double Si02 Yolarilised rosulfate fusion of the &03. Dehydration, HCIOI. Volatilized irom
COhlPARIsON O F
OF
Sample
KtS20; Fusion
irom RzOa
20.52
20.48 20.54 8.16 8.06
No.
Deterrnination
1
SiOt
Fusion 20.50
RaOa
8.16
8.20
2
4
5
22.14
22.12
7.86
7.82
Si02
19.86
19.78
RzOs
8.52
8.84
Summary
19.76 19.82 8.68 8.70
20.10 20.10 8.50 8.62
From this work it appears that in the analysis of portland cement and cement clinker, the silica remaining with the ignited Rz03 may, under carefully controlled conditions, be determined by direct hydrofluorization. A rapid method, in which the silica and R2O3.sH20precipitates are combined, has been tested. Fairly accurate values may be obtained, although there is some evidence that the value for silica may tend to be slightly high. This may be due to loss, as fluorides, of a small amourit of titanium or other elements ordinarily counted in the R203. The use of bromothymol blue in precipitating the hydrous oxides of iron and aluminum has been tested and found to give excellent results.
Si02
21.06
20.94
8.62
8.72
20.95 21.08 8.66 8.58
21.02 21.06 8.62 8.54
SiOn
20.78 20.74 8.70 8.74
20.80 20.86 8.62 8.58
20.88 20.88 8.64 8.5i
20.90 20.86 8.46 8.61
19.46 19.48 9.56 9.52
19.36 19.32 9.58 9.48
19.64 19.66 9.36 9.34
19.66 19.72 9.36 9.28
21.62 21.82 7.86 7.86
21.42 21.50 7.66 7.68
21.74 21.86 7.76 7.76
21.68 21.72 7.84 7.82
Si02 Rn03
SiOn
7
+
22.10 22.20 7.72 7.68
Combined Rn0a 20.56 20.68 8.02 8.12 22.20 22.22 7.68 7.58
SiOz
R2Oa
Rz0a 6
KZs207
RzOs
Bioi
3
139
RzOs
This indicator is chosen because its color change is distinct and covers the p H range (6.0 to 7 . 6 ) in which the isoelectric point of hydrous aluminum oxide occurs ( 2 ) . Several tests hare indicated that no manganese is precipitated with the R2O3.2H20by this method. -Table I11 presents a comparison of values for silica and RZ03in commercial cements obtained by the methods de-
Acknowledgment The authors wish to express their appreciation t,o H. L. Tschentke, B. F. Erdahl, and L. (2.Zack for their assistance with certain analyses.
Literature Cited (1) Am. Soc. Testing Materials, Committee G l , Standards on Cement, pp. 18-20 (December, 1938). (2) Kolthoff, I. >I., and Sandell, E. B., “Textbook of Quantitative Inorganic Analysis”, p. 304, New York, Mai:millan Co., 1936. (3) Macnkon-ske, E. E., J . Research Natl. Bur. Standards, 16, 549-52 (1936). (4) hfeier, F. IT.. and Fleischmann, O., 2. anal. Chem., 88, 88 (1932). ( 5 ) TTillard, H. H., and Cake, W. E., J . Am. Chem. Soc., 42, 2208 (1920).
Toximetric Method for Oil-Soluble Wood Preservatives ERNEST E. HUBERT, Western Pine Association, Portland, Ore. The method described in this article is a correlation of the ideas and laboratory technique developed by the following members of the Preservative Standards Advisory Committce of the Yational Door Rlanufacturers Association and was prepared for publication by the chairman: S. 0. Hall, National Door 3Ianufacturers Association; Geo. 31. Hunt, Roy H. Baechler, C. Audrey Richards, and Theo. C. Scheffer, Forest Products Laboratory; Ira Hatfield, AIonsanto Chemical Co. ; Dale Chapman, A. D. Chapman and Co., Inc.; Gardner Garlick and William Bradley, Protection Products Rlanufacturing Co. ; J. B. )Iellecker, Curtis Companies, Inc.; D. K. Ballman, Dow Chemical Co.; F. H. Kaufert, E. I. du Pont de Nemours & Co., Inc.; J. 0. Frank, RIorgan Co.; Henry Schmitz, University of RIinnesota; and Ernest E. Hubert, Western Pine Association, chairman.
D
i G the past few years interest in treating millwork UR1y products with oil-carried toxic chemicals (1-6) has de-
veloped steadily, and as a result of the rapid and extensive adoption of this type of wood preservative by millwork fac-
tories there has arisen the need for a laboratory test method whereby the numerous proprietary slash preservatives could be evaluated for their toxic properties. The launching, by the Kational Door hlanufacturers Association in 1938, of the “Seal of Approval” program (4)which has as its objective the standardization of all preservative treatment operations and preservatives in licensed mills, has also been a prime factor in the development of a standard toximetric laboratory testing method. The main purpose of this program is “to provide for the identification of windows, frames, and other architectural wood products which have been preservative-treated in accordance with minimum standards of excellence as a protection to the consumers and distributors of such products”. The program also provides for the use by millwork manufacturers of an identification mark, the “Seal of Approval”, to be branded into the treated products as a means of maintaining the high standards of preservative treatment. The preservative minimum standards of the K. D. h1. A. establish the minimum qualities of the toxic* chemical, such as toxicity and permanence in wood; and of the treating solution, such as concentration of toxicant, flash point, volatility, and leachability. Penetration and absorption of
140
INDUSTRIAL -4SD ENGIAEEHIUG CHEllISTRI
the treating solution are specified, as well as the minimum period of submersion of the wood during treatment. Preservative solutions and toxicants new to millwork use must meet the X. D. M.A. minimum standards before they can be used under the Seal of Approval program, and final approval or disapproval of treating solutions rests with the S . D. hI. A. Preservative Standards Committee, which accepts the technical decisions on the effectiveness of such solutions and toxicants from the Advisory Committee. The need, therefore, for a standardized laboratory method of testing these preservatives is evident, and the approved method has made it possible for technical workers engaged in the study of toxicants and treating solutions to compare, within reasonable limits, the results of each others' tests and thus reach a mutual decision regarding the effectiveness of any individual toxicant or treating solution. During 1937 and 1938 a number of organizations were engaged in testing the toxic properties of oil-carried preservatives, and since each worker developed individual laboratory methods of testing it was impossible to compare the results obtained b y the different ones. I n May. 1938, Stanley 0. Hall, secretary-manager of the Sational Door Manufacturers Association, called a meeting of all technical workers engaged in the study of millwork preservatir-es. This meeting was held at Madison, W i a . , on M a y 19 and 20, to discuss the problem and to attempt the establishment of an approved laboratory test method. The group present a t this meeting was organized into the Preservative Standards Advisory Committee and approved a tentative method of testing oil-soluble wood preservatives, using wood blocks uniformly impregnated. During the ensuing year the method mas used extensively and proved very satisfactory, as indicated by the fact that but few minor changes were recommended in 1939 b y the members of the committee. A t the 1938 meeting tentative suggestions for a method of testing the permanence of toxicants in wood-i. e., resistance to leaching in water and to 1-olatihzation-were introduced with the purpose of giving the method a trial and reporting results at the next annual meeting oi the committee. The second meeting of the ildvisory Committee, held a t Madison, Wis., on M a y 16 and 17, approved for publication (May 16, 1939) the K.D. 11.A. standard method of testing the toxicity of oil-soluble materials against fungi as here presented. Also included is the tentative method of testing the permanency of the toxicants in wood as adopted in 1939. The method is believed to give reliable results for comparing the effectiveness of oil-soluble toxicants in wood, and the following allowances for experimental error should be made for losses in weight of treated testblocks until sufficient data accumulate to marrant a change: (a) a 4 per cent maximum loss in weight in any single treated test block, and (6) a 1 per cent average loss in weight for all treated test blocks in a test run. It was generally agreed that as a preliminary measure of the resistance to volatilization of any toxicant, the r-apoi pressure data at 100" C. should be used as a guide.
Testing Materials 1. SELECTIOS OF MATERIAL AND TESTBLOCKS. The nood ubed for the preparation of test blocks shall be average density
kiln-dried Ponderosa pine sapwood. It shall be straight-grained and free of blemishes and defects. Blocks 0.25 inch (0.64 cm.) thick (longitudinal direction) shall be cut from surfaced pieces of wood measuring 1.376 inches (3.5 cm.) on the radial surface and 2 inches (5.09 cm.) on the tangential surface. The surfaces of the blocks shall be smooth, parallel, and free of slivers and dust and each test piece shall be numbered. For each test, ten blocks shall be treated and exposed to each fungus used, and four similarly treated reference blocks shall be placed over uninoculated agar. To serve as controls, ten untreated sterilized blocks shall be exposed to each fungus used and
VOL. 12. NO. 3
four untreated blocks (reference blocks for the control-.) shall be oven-dried in order to give data for use in calculating the ovendried weight of the untreated blocks. 2 . CONDITIOSING OF TESTBLOCKS.Condition all blocks on glass rods to a moisture content of 12.4 * 0.5 per cent by exposure for 20 davs to a saturated solution of sodium bromide (NaBr.2H20) at '26" to 28" C. (An accurately controlled humidity chamber may be substituted.) 3. WEIGHISG. Weigh the test blocks accurately to two decimal places in the humidity room or from a desiccator containing a saturated sodium bromide solution to maintain the moisture content desired %-henhandling the blocks for weighing. Record original weight as 0. 4. VOLUME OF TESTBLOCKS. Measure the first and sixth test block in each set of 10 with an accurate millimeter scale, recording length and width to the second decimal place. Measure the block at the middle of each of the four sides with a micrometer t o determine the thickness. Compute volume and record as V . 5. CULTURE MATERIAL.Kolle flasks or other suitable glass containers shall be used. Make up the nutrient agar for the growth of the test fungi as follow: Grams
Difco bacto agar Trommer's plain diastasic malt extract Distilled water
15 25 1000
After dissolving, pour into each container sufficient agar to support vigorous growth for the duration of the test, stopper, and sterilize, autoclaving for 20 minutes a t 15 pounds' pressure. Inoculate each flask by placing at the center of the medium surface an inoculum block about 1 cm. square with the mycelium side upward. The pure culture of the test fungus shall not be older than 14 days and shall be grown at 26" to 28" C. 6. TESTFUNGI.Test fungi of approved strains obtained from the Forest Products Laboratory shall be used. The test fungus for decay shall be F. P. L. No. 617 Lenzites trabea and for the staining of wood, F. P. L. No. 595 Hom'scium gelatinosum. The inoculated containers shall be incubated at 26" to 28" C. for a period of 21 days, after which the test blocks shall be placed in them.
Testing Methods 7 . PREP.iR.vrIos OF PRESERVATIVE. Preservative shall be tested in the dilution and type of solvent recommended by the manufacturers in half-strength solution obtained by diluting with an equal volume of Stoddard solvent naphtha. 8. 1R.fPREGNATIoSO F TEs! BLOCKS.Place all 14 blocks to be treated in a 2-liter, heavy-walled filter flask and weight them down with glass marbles. Fit a 1-liter separatory funnel into the rubber stopper, connect the flask with a manometer and the vacuum line, and exhaust the flask to a pressure of 125 * 2 mm. of mercury, for a period of 30 minutes. At a temperature of about 25" C. place enough treating solution in the separatory funnel to cover the blocks later. Cut off the vacuum and introduce the treating solution without admitting air. Shake the flask to remove air bubbles from the blocks. Allow the solution to stand for 15 minutes, then break the vacuum. After 5 minutes remove treated blocks, blot off excess liquid, and keep the blocks until weighed in a desiccator over the treating solution used. Weigh the blocks soon after treating and record weight as T . 9. RECONDITIONIKG. Place the treated blocks on glass rods, dry them 13 days in the laboratory air, and then recondition them for 7 days under conditions specified in Item 2. Reweigh the blocks after the 20-day period and record weights of the test and reference blocks as W and G, respectively (see Item 2). 10. IKCCBATION. Place 10 similarly treated test blocks in the containers on two glass rods 0.125 inch (0.32 cm.) in diameter, resting on the surface of the fungus mat. Similarly place ten steam-sterilized (10 minutes at 100" C.) untreated test blocks after conditioning as indicated in Item 2, in other containers. Place 4 treated reference blocks on rods over uninoculated agar. Omit glass rods when using stain fungus. Incubate a t 26" t o 28" C. for 63 days. 11. ER'DOF TEST. At the end of the 63-day incubation period remove the treated and untreated test blocks, scrape clean of mycelium, oven-dry, weigh, and record weight as F. Oven-dry the reference blocks and record as R. Controls should show at least 25 per cent loss in weight due to decay. Since the staining test fungi may show little or no loss in weight for the test blocks, the blocks at the end of the test need not be weighed but shall be evaluated as either clear or stained.
Ah-;ALYTICAL EDITION
MARCH 15, 1940
12. COMPUTATIONS. Volume of test blocks = V T - 0 = A , grams of treating solution in test block _ -- B , absorption in grams per cu. cm.
$
B X 62.44
=
C, absorption in pounds per cu. foot.
% Of toxicant
= D, absorption of toxicant in pounds per 100 cu. foot. I T - = weight' of reconditioned treated blocks and conditioned blocks in case of controls (Item 9) R = Oven-dry weight of treated reference blocks a t end of test, and of untreated reference blocks after sterilization G = weight of reconditioned treated reference blocks, and of conditioned untreated reference blocks in case of controls - = Z, computed oven-dry weight of test blocks before G incubation F = oven-dry weight of blocks after incubation loo = E, % of loss in weight due to decay Z
141
A solution of 5 grams of benzidine in 25 grams of hydrochloric acid and 970 grams of water is prepared. A second solution consists of a 10 per cent concentration of sodium nitrite. Equal amounts of the two solutions are poured together and then applied t o the wood surface by means of a brush or by dipping. The sapTvood immediately shows a yelloivish color, while the heartwood is dark red-brown. The colors remain distinct after drying and the method is effective on various species of pine woods.
Literature Cited (1) Bateman,
E., and Baechler, R. H., Proc. Am. W o o d Preservers
Assoc., 33, 9 1 (1937). (2) Carswell, T. S., and Hatfield, Ira, IXD.EXG.CHmf., 31, 1431 (1939). (3) Carswell, T. S., and Nason, H . K., Ibid., 30, 622-6 (1938). (4) Hall, S. O., "Preservative Minimum Standards", Program of National Door Mfrs. Assoc., Chicago, Ill., 1938. (5) Hubert. E. E.. ISD. EXG.CHEM..30. 1241-50 (1938). (6j Hubert, E. E.', Western Pine Assoc.', Tech. Buil. 6 (1936); rev. ed. (1937, 1938). (7) Koch, J. E., and Krieg, W., Chem.-Ztg., 62 (15). 140-1 (1938).
Volatility Follow the method given RESISTANCE TO VOLATILIZATION. above, with the following exceptions: 13. Use full-strength 5 per cent concentration of the toxicant in the preservative. Continue as in Item 8. 14. RECONDITIONING. Place the treated blocks on glass rods, dry them for 13 days in the laboratory air, then recondition for 7 days under conditions specified in Item 2. Weigh - and record weight as W . TO HE.~T.Expose the test blocks to a tempera15. EXPOSURE ture of 71.1" C. (160" F.) for 24 hours. [Use a triole-u-alled oven with an air capacity of 2.7 cu. feet (0.076 cu. mgter), one 0.875inch (2.23-cm.) air vent a t top, and no artificial circulation.] Remove the blocks and recondition them for 3 days under conditions specified in Item 2. Remove reference blocks, oven-dry, and weigh. Record weight as R. Compute oven-dry wights of test blocks and record as Z. Remove half of the test blocks and incubate as in Items 10 and 11. The remaining blocks are to be run through the leaching test. 16. COMPUTATIONS. As in Item 12.
Leaching
A Weighing Bottle Noyes
W. A. TAEBEL Chemical Laboratory, TJniversity of Illinois, Urbana, 111.
I
T IS rather difficult to transfer finely divided or fluffy material from a n ordinary weighing bottle directly to a volumetric flask without losing some of the substance. The weighing bottle here described offers a n advantage over the common bottle, in that liquids and solids may be transferred directly without danger of loss of material. This may be accomplished by placing the bottle over the neck of the flask, removing the cap and the stopper of the weighing bottle, and washing the contents into the flask. The outside of the funnel stem may be rinsed by directing a stream of water through the aperture shown in the diagram.
RESISTANCE TO LEACHING BY WATER. Follow the method given above, with the following exceptions: 17. LEACHING.Using the blocks which were exposed to the volatilization test (Item 15), place 14 treated and 14 untreated blocks (held down with glass marbles) in separate Erlenmeyer flasks, draw a vacuum for 15 minutes, then break vacuum with 500 cc. of distilled water. Place the flasks in the incubator at 26" to 28" C. Using a siphon, change the water every hour for 7 hours the first and second working days, and every day for the remaining 3 days. Decant the water at the end of each day, leaving the blocks in the stoppered flask for the 16-hour period. At the end of 5 days, remove the blocks and recondition them by drying for 4 days in the air of the laboratory, then for 7 days under conditioning as in Item 2. Remove reference blocks, ovendry, and weigh. Record weight as R. Compute oven-dry weight of test blocks and record as Z. Incubate as in Items 10 and 11. 18. COMPUTATIONS. As in Item 12. 19. Put the 10 untreated controls plus the 4 untreated correction blocks (see Item 2) in every set through the following steps: Items 1, 2, 3, 10 (sterilize all 14 blocks, incubate the 10 control blocks, and oven-dry the 4 reference blocks), 11 and 12. Consider Items 14, 15, and 17 for volatility and leaching tests. K'either the approved pu'. D. R L A. test method for determining toxicity of oil-soluble chemicals in wood nor the tentative methods appended thereto are presented as perfect. They are simply submitted as the method adopted in 1939 by the Advisory Committee. Improvements of these methods or the development of new methods which promise better results will be considered from time to time and the necessary revisions will be made as the committee approves them. I n the selection of sapwood of Ponderosa pine for test material and to be certain that heartwood is not included, a n indicator solution described by Koch and Krieg (7) was found very effective.
Essentially, the weighing bottle consists of a glass tube into which a funnel has been sealed. The stem of the funnel is fitted with an offset ground-glass stopper. The bottle may be made in any size desired, but the stopper would interfere in bottles less than 18 mm. in diameter. The base of the bottle is flanged in order to secure stability. -4ground-glass cap is used to close the bottle. The unit, except for the cap, may be made by anyone who has had some experience in glass b1o.n.ing. The cap may be taken from a n ordinary bottle or from the supply which usually accumulates owing to cracked or broken bottles.
