138
INDUSTRIAL A N D ENGINEERING CHEMISTRY
by the two types of detonators. The greater impression on the lead plates by the nitroglycerol when initiated by the booster type detonator is significant. The initiation of insensitive secondary explosives is, of course, the supreme test of any detonator. A well-known test consists of determining by actual trial the maximum amount of iron oxide that can be mixed with T N T without rendering the mixture incapable of initiation by the detonator in question. A mixture consisting of 92 parts of T N T and 8 parts of iron oxide was found to be on the border line of insensitivity. With fulminate composition detonators 90 per cent failures and 10 per cent detonations were obtained from twenty trials; with the booster type of detonator 100 per cent detonations were obtained. Similar tests on abnormally insensitive nonfreezing dynamites, which were incapable of being consistently initiated by fulminate composition detonators, were found to respond perfectly to the booster type of detonator. The greater initiating efficiency of this type of detonator is, without doubt, due to the greater brisance of the tetryl charge which is efficiently initiated by the azide priming charge. During the war it was a common practice to test the brisance
Vol. 17, No.2
of various explosives by observing the fragmenting power exerted on the container-for instance, on hand grenades.” An excellent idea of the comparative brisance of the detonators in question may be derived from Figure 6. The various detonators were fired in a bomb filled with salt. After the explosion the salt was dissolved and the fragments of the copper shell were recovered. Bibliography 1-Trans. Roy. SOG.London., 90 A, 204 (1800). 2-Liebig, Ann. chim. phys. [2] 24, 298 (1823); Ann., 24, 546 (1837); Nef, I b i d . , 280, 263 (1894); KekulC, I b i d . , 101, 200 (1857); 105, 279 (1858); Wohler, Ber., 88,1351 (1905). 3-Williams, “Munitions Manufacture,” p. 318. 4-W6hler, British Patent 21,065 (November 21, 1900). 5-Curtius, Bey., 23, 3023 (1890). 6-Wislicenus, I b i d . , 25, 2084 (1892). 7-Sto118, I b i d . , 41, 2811 (1908). 18, 970 (1896). 8-Dennis and Doan, J . A m . Chem. SOG., 9-Browne, I b i d . , 27, 551 (1905). 10-Dennis and Browne, I b i d . , 26, 577 (1904): Thiele, Ber., 44, 2522. 3336 (1911). ll-WGhIer, D. R. P. 196,824 (March 2 , 1 9 0 7 ) . 12-Rheinisch-Westfilische Sprengstoff-A. G., D. R. P. 238,942 (June 20, 1912). l3-Colver, “High Explosives,” p. 504.
A Control Method for Boiling Drying Oils’” By J. S. Long and J. G. Smull 1,EHIGH
UNIVERSITY, BETHLEHEM, P A .
variations in the nature of NAMELS used in the Determination of the molecular weight of the oil at vathe surface presented for manufacture of patrious stages of the boiling is recommended as a means of enameling and to differences ent leather nearly securing a uniform and satisfactory product continuously. in the porosity of the skins. always contain a considerThe method has given good results in the laboratory and in It is, of course, desirabIe able proportion of linseed a plant for boiling linseed oil for enamels such as are used that the enamels be as oil that has been boiled unin the manufacture of patent leather. It i s applicable to uniform as practicable. til it has thickened considthe manufacture of lithographic varnishes, linoleum, and Rule-of-thumb methods erably. Driers such as other products made from boiled linseed oil. involving the simple judglitharge, umber, or Prussian The method requires the services of a technically trained ment of “stringing” by a blue are added and boiled man. In such hands it is simple, not expensive, and rapid foreman, although admitinto the oil. The oil is enough to be of service in controlling the boiling. The tedly unsatisfactory, were heated to t e m p e r a t u r e s molecular weight figures magnify any variations in the the only guides in this imranging from 260” to 315” boiling. portant and costly operaC. (500” to 600” F.) and Preliminary laboratory experiments on China wood oil tion. Prevailing scientific stirred, usually by hand. indicate that the determination of molecularweight will be methods of studying oils The progress of the boiling useful in observing and controlling the progress of the boilwere not so satisfactory, in has been observed in the ing of this oil. a practical way, as the empast by the development of pirical methods. As long certain physical characteristics, such as the formation of fine threads, strings, or leaves as this is true the empirical method will prevail. The considof the oil as it drips from the hot ladle used to stir it. eration of the phenomena involved led t o a study of molecular Sometimes samples are withdrawn, cooled, and worked be- aggregation, which not only checked the empirical method tween the thumb and forefinger. The oil is regarded as but led to consistent, dependable results which eliminated “done” when a certain “body” is reached. Thus when the oil the personal equation of the foreman, and which have, with lifts between the fingers in a certain way, giving threads of a unfailing success, been put into daily practice in a large plant. In the literature the thickening of the oil is generally certain length, for example, the kettle is drawn from the fire. It was observed by the authors that, even when holding ascribed to oxidation, although numerous references to to uniform conditions, such as identical oil, same operator polymerization are found. Lewkowitschs refers to the term and kettle, same temperature, etc., from day to ,day, the “polymerized oils” and mentions a few determinations of resultant enamels showed wide variations in their properties, polymerization by molecular weight method^,^ although he indicating a difference in composition. This variation led does not himself use these methods, preferring to place his deto serious difficulties in the manufacture of patent leather, “Chemical Technology of Oils, Fats, and Waxes,” Vol. I, p. 669; the production of which is difficult a t best, owing t o great Vol. *11, p . 121.
E
Received September 3 , 1924. This work was made possible by the assistance of the CallenderCarnell Fellowship at Lehigh University, acknowledgment of which is gratefully made. 1
2
4 Borries, “Oxydation des Leinols,” Dissertation, Leipzig, 1902 : Norman, Chem. Z t g . , 81, 188 (1907); Held, Inaugural Dissertation, 1909, Lieberwolkwitz; Danckworth, “Kryoskopische Wertbestimmung von Drogen,” Leipzig, 1906.
I.VDUSTRIA L A Y D ENGINEERING CHEMISTRY
February, 1925
139
pendence on the more usual analytical data for his judgments mometer was suspended in the oil. About 6fty stirring as to the existence of an increase in the weight of the molecule.6 motions per minute were made. In later runs mechanical stirring was employed. A heavy The progress of the oxidation alone could, of course, be followed by taking samples at various intervals of time and glass rod was bent a t right angles and the bent part flattened determining the iodine number. This idea suggested itself to give a paddle 4 em. long and 1.3 om. wide. This was initially. However, in factory practice the boiling was found driven a t a speedof 200 r. p. m. by afriction-drivemotor. No to be very intimately related to condensation and polymeri- appreciable difference was noted in the results from runs in which mechanical stirring was employed as compared with those stirred by hand. The stirring done in, say, an 800liter (200-gallon) kettle in plant operation in most cases fa& far short of these results. The casserole rested on an asbestos gauze and was heated by a Atblier burner. The flame was protected against drafts by a galvanized iron hood. The dish was covered with a watch crystal in which 2-em. holes were bored for the thermometer and stirrer. In each case, unless otherwise noted, the beating was regulated so that either 15 or 30 minutes were required to bring the oil up to the desired temperature (271' or 293" C.). By occasional regulation of the flame the temperature was maintained constant to 1 2 ' C. Samples were withdrawn with a pipet a t various i n t e r x b 1, 1.5, 2, 2.5, and 3 hours, etc.-and run into small, widemouth, stoppered sample tubes. Samples of about 0.8 gram were accurately weighed into small tubes made by cutting off about 1.5 em. from the bottom of 13-em. test tubes. These were flattened a t the end. The tube containing the weighed Fieure I sample of oil was dropped into a tube containing 25 ec. of sation phenomena, for the appraisal of which molecular benzene in each case. The error in pipetting 25 cc. of benzene weight determinations should offer a satisfactory measure. was determined to be 0.045 per cent. A number of 20cm. The freezing point method was found to be more satisfac- test tubes having as nearly as possible the same bore and thicktory and brought results so rapidly that it could he used in the ness of wall were selected. The freezing point of benzene was plant or the laboratory as a method of control during the determined in each tube. Variation in the temperature of the boiling of a kettle of linseed oil, not only in the manufacture outside bath was minimized by standing the apparatus in of patent leather, but also in the many and varied industries water at 3'to 5'C. in a small crock. in which the boiling of linseed oil is an important objectivee. g., in the production of lithographic varnishes, blown oils, and so forth. Materials Four lots of oils were studied in the laboratory: A-Raw
linseed oil pressed from selected seed
and was then warmed and filtered. D..-Same origin as (C). Pressed in 1919,
These oils had the following constants when this work was done: 1 u c 11
__ ._
specific grarity, 15.5'
~" ,.).aIodine number Saponification number Free fatty acids, per cant
0.9355 165.5
iss.1
2.34
0.9336 178.0
me.0 2.17
0.9330 175.4 193,s 1.39
0.932 173.0
194.0 2.01
BENzENE-Thiophene-free benzene was dried over calcium chloride and then distilled. That portion which came over between 80.0' and 80.3" C. under a barometric pressure of 748 mm. was used. The speciiic gravity wm 0.87373. Apparatus and Method In the earlier experiments in 1920, 100 grams of oil were heated in porcelain dishes having a diameter of 12.7 cm., and the stirring was done with a small porcelain spoon. In the later work 200 grams of oil were heated in a casserole of the same size. Relatively less surface was thereby exposed. The casserole was covered with a watch crystal in which was cut a half-moon shaped hole to permit stirrinr. A ther~
Backer, Chrm. Wcckblnd, 12, 1034 (1915); Monell, J . SOC. Chcm. I d , S4. 105 (1916); Fahiion, Chtm. Umrrhau F a c . O d e , Wochrr *, Hone. 24, 102 i1917); 25. 14 i1918): Friend.3.Chem. S o c . , l l l , 162 (1917): Schcibcr and Nouvel, 2. '"grw. C h r m . , 86, 353 (1923). slso
Figvre 2
The freezing point of tho solution was determined at least twice in each case, or until several determinations agreed closely. A fresh portion of benzene was used for each sample. Table I--100 Grams of 011 D Hand-Sflrred' -DaitnsTern-MOLBCIILA~( WIICIIT-Boil Litharge Umber perafure B a a AfJer 45 After 90 After 135 * C. oil mmiiten minutes minntps No. Grams Grams 1 None 260 691 908 1057 1115 2 1 1 200 691 932 1366 1987 3 2 2 260 691 1039 1318 1792 4 Norre 285 691 909 1031 1202 5 1 2 285 691 1089 1575 2049 6 2 z 285 891 1119 134% 1766 7 None 310 691 925 1063 1227 1 310 691 1128 1706 2011 8 1 9 2 2 310 691 1205 1420 1726 the A, p'c"ented eJ rC quirement for the degree of chernicel enzineer ut Leliigh Uniueis>ty, 1920. ~
,.
~~
~~~~~~~~
~~~
INDUSTRIAL AND ENGINEERING CHEMI8TRY
140
Grams of Oil A Hand-Stirreda * MOLECULAR WEIGH? DRIER Temperature Raw After After After After After After After Gram c. oil 0.5 hour 1.0 hour 1 . 5 hours 2 . 0 hours 2.5 hours 3 . 0 hours 3 . 5 hours None 271 722 940 925 924 961 933 1091 PbO, 0.33 271 722 839 1008 1083 1415 1499 1765 1926 MnB401, 0.40 271 722 830 865 984 1027 1182 1264 1464 None 293 722 1164 1342 1667 1903 2475 PbO 0.66 293 722 1852 2926 3053 Solid jelly MnBdOi, 0.40 293 722 870 1147 1399 1559 2253 Soiih'jelly Results compiled from the thesis of H. G. Rogers, presented as one requirement for the degree of chemical engineer a t Lehigh University, 1924. Table 11-212
--
r
Boil No. 10
11
12 13 14 15
Vol. 17, No. 2
... ... ...
... .... ..
Table 111-1 Boil No.
Oil Grams
:7"
%% {$; 200 (0
18
DRIBR None None
Raw oil 722 744 720
STIRRINC Hand, 50 p. m. Hand, 50 p, m. 200 r. D. m.
None
Hour to R e a c h 293O C."
Up to temperature 1010
...
732
19
230(CJ
720
...
20
200 (C)
720
737
2 76 grams 300 r. p. m. umber 0.4 gram 300 r. p. m. litharge a 20-cm.dish used instead of 12.7-cm. casserole.
Table Boil No.
Oil Grams
21
200 (C)
22
200 (C)
DRIER None 0.4 gram litharge
0.5 0.5
Raw oil
961
1130
1299
1533
After 1.5 hours
After 2.0 hours
After 2.5 hours
After 3.0 hours
Mol. wt.
720
808
981
964
965
Iodine No.
175.4
152.7
148.2
143.3
138.6
Mol. wt.
720
965
953
Iodine No.
176.4
147
136.5
Iodine number 175.4 170.8 155.9 144.5 133.9 125.8 119.3 114.5 105.3
1.n
.gram of oil, which = o*00441 X 100 per cent = 0,441 per cent. The molecular weight increase, however, is of a differGent order of dimension in all cases. Thus, in the case considered it is 124.3 per cent. By condensing part of the volatile products which came off ,during the boiling of linseed oil at 293" C., a liquid was obtained which was strongly acidic, gave positive tests for acrolein, and had a molecular weight of 423. The free fatty acid value of the oil left in the casserole increased to 4.73 per cent, then decreased as follows:
--
872
1518
1886
(Mechanicallv stirred, 200 r. p. m.)
The iodine number decreased from 175.4 to 105.3, a de.crease of 70.1 points-i. e., the difference in iodine absorbed is 70.1 mg. per gram of oil; and since 10 = 2 I, 70,l mg. I is 16 equivalent to X 70.1 = 4.41 mg. of oxygen per 2 X 126.92
100 120 140 160
792
...
IV-031 in 500-Cc. Pyrex Flask in Atmosphere of Nitrogen
Time to reach 293' C. Hour
Molecular weight 720 732 863 937 1063 1190 1346 1511 1613
Time of heating Minutes Original oil 40 nn
...
More surface exposed.
If the change which occurred during boiling was simply the addition of oxygen, the molecular weight increase would be small, and this molecular weight increase could be calculated from the decrease in iodine number. I n some of the runs the iodine number of each sample was determined. The results for Boil No. 18 are as follows: SAMPLB Raw Oil C Up to 293' C. After 0.5 hour After 1 hour After 1.5 hour After 2 hours After 2.5 hours After 3 hours After 3.5 hours
MOLECULAR WEIGHT 7 After After After After After After After 0.5 hour 1 . 0 hour 1.5 hours 2.0 hours 2.5 hours 3.0 hours 3.5 hours 1237 1572 1931 2700 ... 842 9 52 1136 1168 1242 1732 1905 863 937 1063 I190 1348 1511 1613 After After After After After After After After 20 min. 40 min. 1 hour 80 min. 100 min. 2 hours 140 min. 160 min. 851 957 1015 1121 1204 1349 1435 803
Free fatty acids Per cent 1.39 4.73 4.60 4.16 3.97 3.05 3.10
These results are in accord with previously found data, but .are not conclusive in showing the part played by oxidation. To test further the part played by oxygen in the large molecd a r weight increases, several boilings were made in which oxy-
1036 134.6
1020 125.8
After 3.5 hour6 1078 131.5
...
...
gen was rigorously excluded. The oil was heated in a 500-cc., wide-mouth Pyrex flask. This was fitted with a rubber stopper bored with three holes t o admit (1) an 8-mm. glass tube in which the 6-mm. stirrer rotated, (2) the thermometer, and (3) a 6-mm. glass tube leading to within 10 mm. of the surface of the oil. Nitrogen was dried and freed from any oxygen it might contain by passage over a tightly wound spiral of copper gauze, through a tower containing sticks of white phosphorus, and then led into the flask at the rate of 150 cc. per minute. The stream of nitrogen was started before heating was begun and was continued until the end. Samples were withdrawn after 1.5 hours and every half hour thereafter, and the molecular weights determined. The figures for the several runs are given in Table IV. Comparison of these molecular weights with those obtained when oxygen was not excluded shows that oxygen plays an important part in the development of the products with high molecular weights. Discussion Application of the foregoing method to practical factory operation involves no special difficulties. After a little practice the freezing point determination can be made by a trained man with sufficient rapidity to be of use in guiding the boiling and indicating whether the temperature should be raised or lowered. It is advisable to have a number of freezing point tubes and to measure out the benzene into each tube and stopper these before starting the boiling. It is also advisable to determine the freezing point of the pure benzene during the early stages of the boiling, before the first oil sample is taken. Curves plotted between molecular weight and time have been found useful in watching and controlling the progress of the boiling from day to day. After a number of points have been obtained well on towards the end of the boiling, the slope of the curve indicates when a satisfactory molecular weight has been attained, whereupon it is time to draw the kettle. One point found in practice with 340-liter (75-gallon) boilings which was not encountered in the laboratory experiments is worthy of notice. The large mass of oil cooks slowly dependent, of course, on atmospheric conditions and rate of
February, 1925
INDUSTRIAL A N D ENGINEERING CHEMISTRY
stirring during the cooling subsequent to boiling. During the time rcquired for the kettle and its contents to cool from, say, 293" C. to 175' C., or even less, the oil is undergoing further change in molecular weight. Owing to this factor, unexpected discrepancies were found in the product on different days, even though the molecular weights were identical in the different batches when the kettle was drawn off the fire. To overcome this difficulty it was found advisable to take samples during the cooling-for example, at. 245" and 220" C., or even 190" C.-and to determine the molecular weight. If the molecular weight a t 245" C. was greater than that of the 245" C. sample of a preceding batch, stirring was discontinued or lessened and further change thus diminished. If, on the other hand, the molecular weight was lower than expected, stirring was made more vigorous; or in case the temperature had dropped as low as 190"C. without a satisfactory molecular weight, the kettle was put back, the fire relighted, and the oil was cooked for a short additional time. The length of time required to get a certain effect, such as a small molecular weight rise of 50 a t 220" C., was determined by experiment for the kettle under consideration and such data used for the short additional heating. The authors have observed that this procedure of putting the kettle back on the fire is not so unusual in well-run cook rooms as might have been expected. The results in the tables in this paper apply, of course, to a particular lot of linseed oil, and cannot be used indiscriminately for all makes of oil. Different shipments of linseed oil will probably give figures considerably different. It is, of
141
course, possible to check molecular weights of different shipments against some property such as tensile strength, but no such procedure has been found satisfactory. Therefore, when a new shipment of oil is received it is necessary to boil several batches under careful molecular weight control and to determine afresh the optimum conditions in order to arrive at certain desired results. The molecular weights are large numbers and a small variation in boiling makes a considerable difference in the molecular weight. The variation is therefore magnified and attention directed to it. Continued molecular weight studies on the boiling indicated more strongly than any other criterion had previously done the value of buying and tanking a supply of oil sufficient to last for a considerable period of time and thus escaping annoying or ruinous variations in factory practice due to differences in the oil as received. The method outlined for linseed oil has been followed with China wood oil and enough work done to indicate the use of the method in the boiling of China wood oil for various purposes. The molecular weight increased, for example, from 850 to 987 when the China wood oil was heated for 4 hours at 149" C. The authors are continuing the study of the molecular weight changes during the boiling of China wood oil and are further studying the mechanism of the reactions which occur during the boiling of linseed oil, with a view to fixing the limits of condensation, polymerization, and oxidation, or other phenomena involved.
New Laboratory Apparatus' By Fred A. Wiggers PATHOLOGICAL
LABORATORIES, TOLEDO HOSPITAL, TOLEDO, OHIO
Device for Saving Supernatant Fluids
N MANY laboratory procedures it is essential to save supernatant fluids. At times this entails the laborious task of pipetting off the fluid by hand. Especially is this true when the volumes are large. There has been no available apparatus in the market for accomplishing this procedure without losing the fluid into the drain pipes. Most of the mechanical decanting has been with the suction pump. With this method it is evident that the supernatant fluids are lost. Q F With the idea of saving much 4 hand pipetting several years ago, t? the writer devised a simple apparatus to collect supernatant fluids. This was accomplished by c o n v e r t i n g a n o r d i n a r y to~~ecf,,,g straight-sided separatory funnel Tube into a receiving funnel. By elaborating this scheme somewhat a funnel was obtained (Figure 1) that seems to meet all requirements. In detail it is a separatory funnel sfoPcock with a closed roof, an inlet pipet Yacuum for the intake of fluids, and a tube leading to the pump. In principle, u,/ef the pump pulls a vacuum in the Figure 1 funnel, and this vacuum, in turn, pulls the fluid into the funnel. The entire operation can be aseptically carried out and the fluid preserved in a sterile condition. The funnel can be used for any class of work.
I
Received October 11. 1924.
Distilling Apparatus Every laboratory has had the task of distilling and redistilling alcohol or ether or a mixture of both. Either liquid, especially ether, is volatile and great caution is required in distilling them. I n most laboratories the usual procedure has been to distil them over from a flask resting in a water bath. Such methods are cumbersome and often dangerous. Several years ago the writer had a copper jacket arranged about a Florence flask and placed heated water between the two. This method was not entirely satisfactory where an all-glass still was needed, and so the double-flask still (Figure 2) was planned. This is simply a large flask completely incasing a smaller one, leaving a space for water between the two. In practice, water is allowed to enter through the pipet into the space between the flasks. The water is heated and the temperature regulated by a thermometer thrust into a suitable opening provided for it. Toward the top of the neck of the larger flask is a pet cock with a glass stopper to act as a safety valve for steam. The neck of the inner flask rises above that of the larger one and is provided with an outFigure 2 let tube for the vapor to be passed to the condenser. This outlet tube fits like a ground-glass stopper and the whole apparatus is easily cared for and kept clean.
