dS A L Y TI CAL EDI TI 01;
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regular reflection of a perfectly polished surface as the angle of incidence is increased. It has been possible to use the average of these readings and get quite consistent results. I n order to get more accurate values it would be necessary to make measurements for a large number of angles and average the results, but it is questionable whether the amount of work involved would be warranted b y the increased accuracy to be obtained. Table I indicates that, in the vehicles studied, zinc oxide gives the highest gloss and that in general the vehicles containing perilla oil give the best results with any of the three pigments. It will be noticed that in several instances higher
Vol. 2, KO.3
gloss readings were obtained on the exposed panels than on the unexposed. This was checked visually and found to be t r w . although no explanation is offered for the phenomena. Average results indicate a loss of gloss on exposure. Acknowledgment
The authors wish to acknowledge the helpful criticism of A. H. Pfund and the assistance of Victor Bachman in making. the measurements. L i t e r a t u r e Cited (1) Pfund, J. Optical SOC.A m , 20, 23 (1930).
Standard Methods (Revised) for Determining Viscosity and Jelly Strength of Glue Adopted by the National Association of Glue Manufacturers Atlantic City N J October 10, 1923. Published in Industrial and Engineering Chemistry, Vol. 16, j l 0 (1924). Redsidn adopted April 10, 1930.
(A) S a m p l i n g a n d P r e p a r a t i o n of S a m p l e 1. GROUNDGLUE OR
EQUIVALENT-A grab sample in the
ratio of 1 ounce per 100 pounds (28 grams per 45 kg.) shall be taken at random from not less than 20 per cent of the containers, except that the total number of samples so taken shall not be less than ten. When the number of containers in the shipment is less than ten, samples shall be taken from each container. GLUE,ETC.-sample shall be taken as out2. SHEET,FLAKE lined for ground glue, except in cases of large lots, where the entire sample drawn will amount to more than 10 pounds (4.5 kg.), in which cases the portion taken from each container shall then be reduced proportionately so that the total sample drawn shall not exceed 10 pounds (4.5 kg.). 3. GRINDINGOF SHEET, FLAKEGLUE, ETc.-The entire sample as drawn above shall then be ground in any suitable manner, to a t least 4 mesh, or finer if in the judgment of the operator it appears necessary, so as to minimize weighing errors and to shorten the soaking period. FOR TEsT-The entire ground sample as drawn 4. SAMPLING and prepared above is then thoroughly mixed and quartered down until reduced t o two 1-pound (454-gram) samples, which shall be placed in air-tight containers. One of these is to be used for test and the other shall be held as a reserve sample.
(B) T e s t i n g of S a m p l e
I, COXCENTRATION AND QUANTITY OF SoLuTIoK-samples are made up in duplicate a t a concentration of 12.5 per cent by weight. Since a minimum of 100 cc. of solution a t 60" C. is required for the viscosity determination, 15.00 =t 0.03 grams of commercially dry glue are weighed out and transferred without loss to the standard container (described in D-2), and 105 * 0.25 grams of distilled water a t approximately 15" C. are added while t h e glue is being thoroughly stirred with a thin metal rod. A metal rod is preferable to one of glass, since small glue particles will not adhere to the former when it is wet. If the end of the rod is pointed, particles in the comer of the container can be reached. The container is now closed with the perforated stopper. 2. SOAKING TEMPERATURE-The samples are then placed in a cooler, ice box, or other compartment held a t a temperature of 10' t o 15" C. 3. SOAKINGPERIOD-In view of the variations in subdivision and grade of glue samples, the committee does not consider it
advisable to fix the exact length of the soaking period. It must, however, be long enough t o soften the glue thoroughly. Soaking overnight is sufficient for all glues. It has been demonstrated that shorter time is permissible for some samples, but such a change in procedure should only be made in the light of experience justifying same. 4. PROCEDURE FOR MELTINGOF SAMPLES-In order not t0 crack the thick-walled containers, they should be placed for a few minutes in water of 20" t o 30' C. before being put into the melting bath. The sample is then placed in the melting bath, the temperature of which is not allowed to exceed 70' C., and brought to a temperature of 62" C. as determined by an accurate thermometer placed in the glue solution and carrying one of the stoppers described but with a small perforation off center. The stopper originally closing the container is placed aside until after the viscosity determination has been made, when it is again used to close the bottle. The time required to bring the sample up to temperature should not exceed 15 minutes and, having attained the required temperature, there should be no delay in transferring the sample to the viscosity pipet. After closing the container with the stopper carrying the thermometer and before reaching the final temperature, the solution must be made thoroughly uniform, preferably by swirling the container a number of times. Any motion that will produce violent agitation of the solution should be avoided. I n order to keep the supply of samples to the pipet continuous, several samples will have to be in the process of melting a t t h e same time. Moreover, they should leave the bath in the same order that they entered it, so that all samples will have been subjected to as nearly identical thermal conditions as possible. The maximum number of samples present in the bath a t any one time will depend largely upon the speed with which the subsequent viscosity determinations are made. A short trial will determine the correct number. Samples of low-grade glues heat through more rapidly than the more viscous high-grade ones and can be brought to temperature faster than the latter. The time required t o make the viscosity determination varies in the same direction; hence the number of samples in the melting bath a t any one time becomes fairly constant.
(C) Viscosity D e t e r m i n a t i o n 1. VISCOMETER-The committee has adopted a pipet form of viscometer for glue solutions, which is a modiiied Bloom viscosity pipet. This type of viscometer furnishes a rapid and, when used
July 15, 1930
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I S D U S T R I A L A X D E.LTGI.VEERILVG CHEMISTRY
under proper conditions, a sufficiently accurate means of determining the viscosity of glue solutions. (Figure l) 2. TEMPERATURE CONTROL-The pipet is jacketed with water held a t a temperature of 60" * 0.2" C. by a n electrical heating device. Approximately complete immersion of the heating element is desirable, and temperature control can be accomplished by the insertion of variable external resistance in series with the heating element, A Centigrade thermometer graduated in 0.1 degree is used to determine the temperature of the glue liquor after its introduction into the pipet. 3. STOPIVATCH-A watch graduated in fifths of a second and checked for accuracy should be used. I t is recommended that the watch be of the type that runs continuously when wound, and not of the type whose whole mechanism is set in motion when the stem is pressed, as it has been observed that there is a lag in the time recorded due t o this acceleration of the mechanism. 4. L\SSEMBLIh.G .4ND SETTIXG UP VISCOSITY APPARATUSThe assembling and setting up of the viscosity apparatus is described in the circular sent out with each set. A few additional suggestions may be added here. If the water jacket, when fixed in position, is not held firmly by the upper ring, the ring should be covered with a piece of rubber tubing slit lengthwise and of thick enough wall t o prevent further play of the bottle in the ring clamp. This precaution serves t o prevent the breakage of the pipet a t the capillary end. The water-jacket drain tube may also be used for the introduction of the compressed air when this is used for agitation of the bath. Small sections of rubber tubing slipped over the jaws of the buret clamp used t o hold the upper part of the pipet in position will make a snug fit and thus reduce the chances of snapping off the capillary end. The end of the capillary tube should extend approximately '/le inch ( 2 mm.) beyond the rubber stopper. Care should be taken that the viscometer is in a vertical position and t h a t it is not held in position under strain. The water in the jacket must be gently agitated so that not more than 0.2" C. difference in temperature exists between any two points of the bath while the determination is being made. 5 . CALIBRATIOS OF THE VISCOMETER-This is fully discussed ENG.CHEM.,15, 1109 (1923)] and in the in published data [IND. circular accompanying the apparatus. 6. THE VISCOSITY DETERMINATION-The sample, prepared a s directed in section ( B ) , is transferred t o the pipet as quickly as possible without entrapping air. Enough of the solution is poured into the viscometer t o bring its level about 1 cm. above t h e upper mark on the pipet while a finger of the free hand closes t h e capillary end. The residual liquor is left in the container and t h e latter placed on the iron stand directly under the exit tube. The special Centigrade thermometer furnished with the apparatus is placed in the pipet and slowly lowered and raised until it registers and maintains the temperature of 60.0' C. when its bulb is about midway between the top and bottom of the bulb of the pipet. The thermometer is then removed and the level of the solution adjusted t o the upper mark. When not in actual use the thermometer should be placed t o nearly its full length in water having a temperature slightly above 60 O C. It should, of course, be wiped dry before use. The time required for the 100 cc. of solution t o pass through the capillary tube of the viscometer is obtained by simultaneously starting the watch and withdrawing the finger from the end of the tube and then stopping the watch when the level of the solution has reached the lower mark on the pipet. The container is then closed with the original perforated stopper and the sample used for the jelly strength determination. After each determination and also before using after the apparatus has been idle for any length of time, the pipet is washed out with about 25 CC. of water heated t o 62" C. and allowed to drain thoroughly. When not in use the funnel end of the viscometer should be covered t o prevent the entrance of foreign matter.
The viscosity is to be expressed in the nearest whole m i l l i p o i s e calculated according t o t h e formula appearing on the certificate of calibration accompanying each pipet and as described in the circular. The viscosityrange of ordinary commercial glues is approximately 20 to 175 millipoises.
n
(D) Jelly S t r e n g t h Determination 1. GELORIETER-The committee has a d o p t e d t h e Bloom gelometer a i the official instrument of t h e a s s o c i a t i o n for making t h e jelly test of glues. (Figure 2) It has been found to give d u p l i c a t e results under identical c o n d i t i o n s , is e a s y of operation, arid capable of exact duplication in c o n s t r u c t i o n , p a r t i c u l a r l y of fundamental parts. 2. CONTAINER F O R T H E JELLY-The cont a i n e r recommended is an extra wide mouthed bottle of the following specifications: Capacity 150 cc. Diameter of body: Inside 59 mm. Outside 66 mm. Height over all 85 mm. To take rubber stopper No. 9.
F i g u r e 1--Standard Viscosity P i p e t A-Upper etched line B-Lower etched line C-Clamp supporting pipet D-Clamp supporting heating element E-Ring clamp supporting water bath F-Water bath (5-pound bottle, bottom cut
Bottles showing a variation of more than 1mm. in G-DrainOff) tube support average internal diameter H-Iron J-Thermometer from these d i m e n s i o n s K-Terminals t o heating element L-Heating element s h a l l b e rejected. The M-Capillary efflux tube supporting water bath tapered stopper is cut In N-Ring 0-Rubber stopper half and the upper portion P-Compressed air connection for agitation S-Iron stand is perforated by plunging T-Calibrated viscosity pipet a red-hot, I-inch (2.5-cm.) brad through it a t the center. The ui)per half of the stopper is used t o obtain a snug fit in the neck of the bottle and the air vent prevents the stopper from being blown out during the melting and heating of the sample. It is not necessary t o emphasize t h a t the containers and stoppers must be clean and dry. 3. METHODOF CHILLINGGLUESoLcTIoxs-The sample from the viscosity determination in t h e tightly stoppered container is allowed t o cool t o 45' C., preferably in a water bath maintained approximately a t this temperature. The finger is then placed over the perforation in the stopper and the container inverted several times t o mix in the water that has condensed on the walls of the bottle and the under side of the stopper. The container is then placed in a constant-temperature chill bath for not less than 16 nor more than 18 hours a t 10" * 0.1" C. The committee wishes t o call attention t o the importance of the temperature variation of the chill bath. Unless the bath controls t h e temperature within the limits prescribed above, it will be necessary t o use "standards" and thus make relative and not absolute tests.
-4A-A L Y T I CL4L EDI T I O S
1-01. 2 , To. .;
PART REALVIEW
FRONT
VIEW
Figure 2-The
A-Brass contact point bracket AI-Upper contact point Az-Lower contact point Aa-Wood fiber support for A A r - S e t screw t o hold adjustment screw in position As-Adjustment screw for A inch thick B-Pure silver disk ( 6 / 8 inch diameter and C-Electromagnet Cz-Adjustment screw for adjusting pitch of clam cut-off E D-Guide bar of automatic shot control mechanism DI, Dz, 0 3 , Dd, Dj-Lower dog Ds-Upper dog Di-Hair spring coil t o keep Ds in position Da-Soft iron bar supporting dogs Di t o Do E-Clam-shell spout El-Stationary clam-shell jaw E*-Adjusting screws t o regulate closure &"- N e.. i v_.o___ ht _
Ea-Clam-shell arm Ej-Set screw t o clamp weight t o clam-shell a r m on which cut-off mechanism turns Ea-Bearing F-Spiral spring (NO.6 steel music wire) G-Adjustable support for spring F GI-Thumb screw n u t Gz-Tension spring OF JELLY STREXGTH-The determination 4. DETERMIXATION of the jelly strength of the sample is made with the Bloom gelometer,, adjusted t o give a 4-mm. depression and t o deliver shot a t the rate of 200 grams per ,5 seconds when the clam-shell arm, Ed, rests upon dog D2, and 800 grams of polished No. 12 chilled lead shot are in hopper I. Specific directions for making these adjustments accompany each instrument. All determinations
Bloom Gelometer
S I D E VIEW
Hi-Pan arms Hz-Pan Ha-Rod attached t o pan arms supporting disk B I-Shot hopper with delivery tube Il-Bracket t o hold lower end of shot delivery tube J1-Upper supporting bracket attached t o frame support Rz Jz-Lower supporting bracket attached t o frame support R, Jza-Guide arm attached t o Jz R-Shot receiver (12.7 mm. in diameter) L-Plunger .If-Test bottle S-Elevating platform base S1-Platform 1.2-Rack and pinion elevating mechanism Sa-Fine adjustment on rack and pinion Sa-Brake shoe on adjustment a r m of 0-Battery box and batteries @-Electrical switch R:-Base of gelometer K?-Pillar of gelometer S-Fine copper wire coil making contact across from suspended disk t o binding post on support T I , T?-Leveling screws 7's-Spirit level
are made from the dog D2, the results to be ehpressed in the nearest whole gram required to produce the 4-mm. depression as prescribed above.
(E) Chill Bath The committee has adopted as the official chill bath of the association the equipment manufactured by Sarco Company,
INDUSTRIAL AND ENGINEERING CHEiVISTRY
July 15, 1930
Inc. This bath is capable of being controlled within the above prescribed limits and holds approximately seventy-five samples. -4lthough this bath has been found to be quite satisfactory, the committee wishes only to emphasize the conditions under which the samples must be chilled and obviously any equipment which is capable of operating within the prescribed limits will be satisfactory to use. (F) General Precautions As a result of several years of testing experience using the above-described equipment and methods, the committee wishes to emphasize the following general precautions: 1. GENERAL: (a) Check all balances used. ( b ) Check of soaking and melting procedures. (c) Check all thermometers, especially those used in chill bath and viscosity determination. Thermometers furnished for precision work are sometimes found to be inaccurate t o as much as 0.5 degrees. Therefore, all should be checked for accuracy against a reliable standard. 2 . JELLY STRENGTH: (a) Check of gelometer prior to every series of tests for correct rate of shot flow (200 grams * 6.0 per five seconds). n’ith continued use the shot wears unevenly, thus affecting the rate of flow. It should, therefore, be renewed from time to time. ( b ) Frequent check of 4-mm. gap between contact points.
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(c) Proper leveling of gelometer. ( d ) Condition of batteries. ( e ) Maintenance of correct temperature of bath during chilling period. (f) Uniformity of temperature throughout the bath. (g) Checking of jell surface (foam, unevenness, etc.). ( h ) Keep shot for gelometer clean, dry, and well protected in a closed container when not in use. 3. T’ISCOSITY: (a) Check accuracy of stop watch. ( b ) Check position of delivery tip of pipet. (c) Cleaning of pipet. ( d ) Proper temperature control. ( e ) Report results in absolute units and not kinematic viscosity.
Notes o n Special E q u i p m e n t Required
1. CONTAIXERS-The test bottles may be purchased in case lots from hlillville Bottle Works, Millville, X. J., mold No. 1016, and in smaller quantities from Central Scientific Company, Chicago, Ill. 2. THERMOMETERS-The thermometers recommended may be purchased from Taylor Instrument Company, Rochester, N. Y . , by specifying titer thermometer No. 1425.
F. I,. DEBEAUKELAER J. R . POWELL E. F. BBHLMANN Committee Revised 1930 by Technical Committee M. L. SHEELY,Charrman
Recommended Specifications for Analytical Reagent Chemicals‘ Calcium Carbonate, Calcium Carbonate Low i n Alkalies, Calcium Chloride (CaC1,.2H2O), Cupric Oxide Wire Form, Cuprous Chloride, Lead Acetate, Magnesium Sulfate, Sodium Metal, Zinc Sulfate Gregory P. Baxter, W. D. Collins, H. V. F a r r , J. V. F r e e m a n , Joseph Rosin, G. C. Spencer, a n d Edward Wichers COMMITTEE
O S .biALYTICIL
REAGESTS, .hERICAS CHE)IlIC.AL SOCIETY
T
HE specifications given below are intended to serve for
reagents to be used in careful analytical work. The limits and tests are based on published work, on the esperience of members of the committee in the examination of reagent chemicals on the market, and on studies of the tests made by members of the committee as the various items were considered. Suggestions for improvement of the specifications will be welcomed by the committee. In all the directions the acids and ammonium hydroxide referred to are of full strength unless dilution is specified; dilution 3) means 1 volume of the reagent or strong indicated as (1 solution with 3 volumes of water; “water” means distilled water of a grade suitable for the test described; reagents used in making the tests are supposed to be of the grade recommended below or in previous publications (1, 2, 3, 4, 5 , 6 ) from the committee. Directions for the preparation of the ammonium molybdate solution are given under the test for phosphate in ammonium nitrate ( 3 ) . A time of 5 minutes is to be allowed for the appearance of precipitates and before observation of color reactions, unless some other time is specified. Blank tests must be made on water and all reagents used in the
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1 Received June 4 , 1930. Presented in connection with t h e report of the Committee on Analytica! Reagents a t t h e 79th Meeting of the -4merican Chemical Society, Xtlanta, Ga., April 7 t o 11, 1930.
tests unless the directions provide for elimination of errors due to impurities. Solutions of samples must be filtered for tests in which insoluble matter would interfere. Calcium Carbonate RE~UIREVESTS
Insoluble i n Hydrochloric Acid and .1mmonium Hydroxide PrecipihteS o t more than 0.030 per cent. Alkalinity-To pass test. Chloride (CI)--Sot more than 0.001 per cent. Xitrate (Nos)-To pass test (limit about 0.003 per cent). Sulfute (SOa)--Sot more than 0.010 per cent. A m m o n i a (NHa)--?;ot more t h a n 0.003 per cent. B a r i u m (Ba)-To pass test (limit about 0.005 per cent). Heavy Melals (as lead)-Not more than 0.001per cent. Iron (Fe)--Sot more than 0.003 per cent. Magnesium awd A l k a l i Salts (as sulfates)--Xot more than 0.50 per cenl.
TESTS Insoluble i n Hjdrochloric A c i d and .1 mnionium Hydroxide Preci9ituteTreat 5 grams with 100 cc. of water and add hydrochloric acid little by little until all the carbonate is decomposed. Boil t h e solution t o expel t h e carbon dioxide and dilute t o about 100 cc. Render slightly alkaline with a m monium hydroxide (free from carbonate) and boil for 5 minutes. If a precipitate is formed, filter through a small paper, and wash with a little hot water. Reserve t h e filtrate for t h e test for sulfate. Redissolve t h e pre21, boil t h e solution (which cipitate with hot dilute hydrochloric acid (1
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