Tan.. 1 0 2 1
iirr absence of I
,
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
any predetermined governmental policies, left the laboratory free to develop along natural lines and to take up the industrial and agricultural problems of most immediate and pressing importance. The great benefit of the laboratory was quickly felt and the scope of its work was widened when,
SIRFRANCIS WATTS,K.C.M.G., D . S C . AGRICULTURE FOR THE
IMPERIAL COMMISSIONER OF
W E S T INDIES
with the establishment of the Imperial Department of Agriculture for the West Indies in 1898,the local Antigua laboratory became a federal institution, with its field enlarged to comprise St. Kitts, Nevis, Montserrat, and the Virgin Islands. Immediately preceding this, Dr. Watts occupied for about a year the position of chemist to the government of Jamaica, but relinquished this post after the creation of the Imperial Department, to accept in 1899the appointment of government chemist and superintendent of agriculture for the Leeward Islands. He retained this position until January 1909,when he was appointed to his present office of Imperial Commissioner of Agriculture for the West Indies. From the beginning of his scientific career in the West Indies, Dr. Watts has maintained a close contact between the chemical laboratory and the Agricultural and Botanic Experiment Stations, and he has continued this policy of scientific cooperation in all his subsequent administrative work. The effect of this
has been most beneficial, as results were secured which could not have been accomplished had chemical, agricultural, botanical, and industrial research proceeded along separate unassociated lines. The training of young students for the varied needs of industrial life in the tropics is a subject to which the Imperial Department of Agriculture has given much attention and a considerable amount of Dr. Watt’s time in late years has been devoted to questions of education. I n addition to their usefulness as centers of research, the experiment stations and laboratories have been made t o serve as training places where young students may acquire practical first-hand knowledge of the subjects taught in the elementary and secondary schools. With the recent rapid growth which has taken place in developing the resources of the British West Indies a strong need has been felt for a central higher institution of, learning where advanced students could obtain a complete theoretical and practical training in the production of sugar, cacao, rubber, and other agricultural commodities. The new Tropical College, for which Sir Francis Watts has so long been working and which is soon to be established in the island of Trinidad, will remedy this need. Trinidad is an ideal location for the new institution, for not only is it conveniently situated with reference to the colonies in t h e West Indies and British Guiana, but with its varied industries of sugar, cacao, rubber, limes, and copra, as well as of asphalt and petroleum, it offers the student almost unlimited natural facilities for study and research. This college will be of much benefit to the Empire as a whole, as well as to the colonies most immediately concerned, for up to the present time the graduates of English universities who take up scientific work in the tropics have lacked facilities for acquainting themselves with the requirements of their new duties. The committee who have the matter in charge regard it as desirable that an intimate relationship should exist between the Tropical College and the Imperial Department of Agriculture, and have recommended t h a t the first president of the new institution should be the Imperial Commissioner of Agriculture. The wide experience of Sir Francis Watts in the agricultural, industrial, and educational life of the West Indies is sufficient proof of the wisdom of this recommendation. While the administrative duties of Sir Francis have obliged him t o withdraw from active work in the laboratory, his original interest in chemistry has continued unabated, and it is safe to predict that under his leadership chemical research, as a means of developing the industrial and agricultural resources of the tropics, will b d an important place in the curriculum of the new college. Sir Francis Watts by visits and by correspondence has always kept in close touch with the work of his scientific confreres in the United States, as well as in other parts of the world. He has been a visitor a t the Chemists’ Club in New York, and those who have met him there recall with pleasure his charming cordial personality. His fellow members of the AMERICAN CHEMICAC SOCIETY not only congratulate him for his enduring accomplishments but extend to him their best wishes for long (years of helpful activity t o come.
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RESEARCH PROBLEMS IN COLLOID CHEMISTRY
I
By Wilder D. Bancroft CORNELL UNIVERSITY, ITHACA, N. Y Received November 5 , 1920
The following list of problems was compiled a t the request of Prof. H. N. Holmes, Chairman of the Committee on the Chemistry of Colloids of the Division of Chemistry and Chemical Technology of the National Research Council. I have received
valuable assistance in preparing this list from Messrs. Holmes and Weiser. The arrangement is somewhat arbitrary because almost any one of the problems could have been entered under a t least two
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
a4
heads, depending upon the particular aspect of the problem that interested one; but a poor classification is distinctly better than none a t all. It is hoped that the publication of this list will stimulate research in colloid chemistry. The committee will be glad t o receive suggestions as to additional problems. I n order to keep in touch with what is being done in this country and in order t o prevent unnecessary duplication of effort, the committee will appreciate it if anybody who starts work on any of these problems will send word to that effect t o Prof. H. N. Holmes, Oberlin, Ohio, who will furnish additional information, if desired, and who will also have copies of the list for distribution. ADSORPTION OF GAS OR VAPOR BY SOLID (I )
,
PRESSURE-CONCENTRATION ADSORPTION CURVES FOR HIGH PRESSURES-It is believed that the adsorption isotherm for gases has the sgme general form as the adsorption isotherm for solutions and that a t high pressures the adsorption varies very little with increasing pressure. Dewar' claims t o have obtained an isotherm of this type with hydrogen in charcoal a t -185'; but he finds an adsorption of 156, 149, 145, and 138 cc. per gram for pressures of IO, 15, 20, and 25 atmospheres, respectively, and these adsorptions are not strikingly constant. At ordinary temperatures and pressures the adsorption isotherm for hydrogen in charcoal is nearly a straight line.2 Richardson3 gets approximately the theoretical curve for ammonia in charcoal a t - 6 4 ' While there is no doubt and nearly a straight line a t +175'. but that the nearly linear curves bend round a t higher pressures, this should be proved experimentally. (2) ADSORPTION ISOTHERM FOR COS ABOVEAND BELOW THE CRITICAL TEM~E~ATvRE-Mitscherlich~calculated that, when carbon dioxide a t atmospheric pressure and I 2 ' is adsorbed by boxwood charcoal, the carbon dioxide occupies only one fiftysixth of its original volume. Since this is a lesser volume than the same amount of carbon dioxide can occupy as a gas a t this temperature it is usually assumed that part has liquefied. This assumption is the more probable because the heat of adsorption of a gas or vapor is always somewhat larger than its heat of liquefaction.& It has been pointed out, however, by Mr. Johnston that an adsorbed gas may be in such a state that i t does not liquefy even when compressed into a volume which it could not occupy as gas in the free state. It is difficult to account for the heat of adsorption on this view. The best way to test this hypothesis would seem to be t o determine adsorption isotherms for carbon dioxide a t temperatures above and below its critical temperature, and a t pressures up to those a t which i t would liquefy in absence of charcoal. It is quite possible that these experiments would throw Some light on the form of the adsorption isotherm as discussed in No. I . If Richardson's results with carbon dioxide were plotted on a different scale, they might answer the question. ( 3 ) DATA TO SHOW THAT THE ORDER OF ADSORPTION O F GASES THE BOILING POINTS-
AND VAPORS IS NOT NECESSARILY THAT O F
I t is often stated as a first approximation that a gas or vapor is adsorbed more readily the higher its boiling point. Thus, helium is adsorbed by charcoal much less than hydrogen, and hydrogen again is adsorbed to a much xtent than nitrogen or oxygen. Carbon dioxide is adsorbed less readily than ammonia, so these substances follow the empirical rule. Argon, however, is adsorbed less completely by charcoal than is nitrogen, while carbon monoxide is adsorbed to a greater extent a t 0 ' than either argon or oxygen, though this is not according t o the rule. Nitrous oxide is adsorbed less strongly than ethylene, and nitric oxide PYOC.Roy. Inst., 18 (1906), 437. Titoff, Z . pkysik. Ckem., 14 (1910), 641. 8 J . A m . Ckem. Soc., 38 (1917), 1828. 1 Sits. A k a d . Wiss. Berlm, 1841, 376. SFavre, Ann. ckim. pkys., [SI 1 (1874), 209; Lamb and Coolidge, J . A m . Ckem. Soc., 4!4 (1920), 1146. 1 2
Vol. 1 3 , KO.
I
more strongly than methane, which is not according to the boiling points. Ethane, ethylene, and acetylene are adsorbed more a t + 2 0 ° than is carbon dioxide, though the last is the most readily condensable gas of the four. The difference between carbon dioxide and hydrogen sulfide is in the right direction, but seems out of all proportion to the difference in boiling points. Hydrogen sulfide is adsorbed more than ammonia, although the two boiling points are practically identical. Cyanogen is adI n the case sorbed more than ammonia a t 70' and less a t o'. of vapors there is no apparent relation between boiling point and.adsorptian by charcoal. Going from higher to lower boiling points, we have the order: water, benzene, ethyl alcohol, carbon tetrachloride, methanol, chloroform, ether, and acetaldehyde. The order from greater t o lesser adsorption is: ethyl alcohol, methanol, acetaldehyde, ether, benzene, water, chloroform and carbon tetrach1oride.l There should be a systematic study of the relations so that comparisons could be made a t corresponding temperatures and pressures. At temperatures below the critical temperature, the limiting adsorption depends only on the pore space and on the amount of contraction which the adsorbed liquid undergoes. (4) REPETITION OF HUNTER'S EXPERIMENTS ON THE ADSORPTION OF GASES BY DIFXERENT WITH STEAMAT z~o'-Hnnter2
CHARCOALS AFTER TREATMENT
found that charcoals made from different woods behaved differently. The coconut charcoal had the greatest adsorbing power of all. Of the others, charcoal From logwood was the best with ammonia, charcoal from fustic the best with carbon dioxide, and charcoal from ebony the best with cyanogen. These results should be checked t o make sure that they are correct. The varying relative adsorption of different gases by diflerent charcoals is probably due a t least in part presence of different adsorbed impurities which affect t fent gases differently. The different charcoals should be treated with steam at 250' t o 300' in order t o remove ible of the adsorbed impurities, and should then ( 5 ) THE ADSORPTION O F AMMONIA BY AMMONIUM HYDROS u ~ F ~ ~ E - M a g n u s s ofound n~ that the adsorption of ammonia by ammonium hydrosulfide was sufficient to introduce a serious error into the determination of the equilibrium relations for ammonia and hydrogen sulfide. The problem should now be reversed and a study made of the adsorption of ammonia by a porous mass of ammonium hydrosulfide. ( 6 ) STUDY OF VAPOR PRESSURE CURVES O F ADSORBED WATERWe get rather curious results if we apply Hatschek's view4 on viscosity to Bingham's experiments6 on zero fluidity. If we make the assumption that plastic flow is reached when the surfaces of adsorbed water are in contact, and if we make the further assumption that we are dealing with spheres in open piling, the voids will then be 48 per cent of the whole, and in the case of graphite, for instance, the amount of water adsorbed by the graphite must be 94.5 48 = 47.5 volume per cent, or each volume of graphite must adsorb about nine volumes of water. If we assume close piling or different sizes of graphite powder, the voids will be less and the amount of water to be adsorbed will be greater. Since the volumes of two spheres are proportional t o the cubes of the radii, one volume of graphite will hold seven volumes of water if the thickness of the water film is equal to the radius of the graphite particles. If the thickness of the water film is 1.2 times the radius, the graphite will hold eleven volumes of water. This is the same type of calculation
-
1 Hunter, Phil. Mag., [4] 25 (1863), 364; J . Ckem. Soc., 1 s (1865), 285; 20 (1$67), 160; 21 (1868), 186; 28 (1870), 73; 24 (1871), 76; 25 (1872). 649; Dewar, Proc. Roy. Soc., 74 (1904). 124: Hempel and Vater, 2. Elektrochem., 18 (1912), 724. 2 Pkil. Mag,, [4] 25 (1863), 364. 8 J . P k y s . Chem., 11 (1907), 21. 1 2 . Kolloidckem., 11 (1912), 280. 6 J. Frank. Inst., 181 (1916), 845.
Jan., 1921
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that Hatschek made, and it shows that it is theoretically possible on this assumption to account for zero fluidity in a graphitewater mixture containing 5.5 per cent graphite. It has not been shown, however, that the adsorbed films of water on the graphite particles are of the desired thickness, nor has it been shown that 47 per cent of the water in the mixture is in a different state from the rest of the water. It might be possible to do this last by measuring the vapor pressure curve for graphitewater mixtures and determining the point a t which the vapor pressure became that of pure water. (7) APPARENT VOLUME OF POWDERS I N A VACUUM-ASlittle as 5 per cent of the apparent volume of a mass of carbon black may be due to the solid,’ and a liter of carbon black may contain 2.5 liters of air.2 If the adsorbed air were all pumped out, the apparent volume of the carbon black would undoubtedly be very much less; but nobody has actually proved it. An experiment t b prove this would be interesting because it would furnish a new proof of the existence of the film of adsorbed air. It is also important to know the true voids in a mass of carbon black or other substance, because this value plays an important part in the theory of viscous and plastic flow as developed by Bingharn.8 Still more striking results could probably be obtained by working in a n atmosphere of carbon dioxide or of ammonia, especially if powdered charcoal were substituted for carbon black. When indigo is reduced to a very fine powder by means of a disintegrator,‘ the single particles appear to be separated one from another by an envelope of air, so that the dry powder occupies only 20 per cent of the apparent volume. Cushman and Coggeshall’ found that cement rock powder which would pass through a zoo-mesh sieve surged like a liquid because of the film of adsorbed air. When poured into a vessel the fine powder filled only 46 per cent of the space, while a coarser powder filled more. Finely ground phosphate rock also flows like a liquid. I n all these cases pumping out the adsorbed air would undoubtedly make the powders pack more closely, but this has not yet been proved experimentally. (8) EFFECT OF COMPRESSING POWDERS I N PRESENCE O F ADSORBED GAS-PhtinUm black takes up a great deal more hydrogen than does platinum foil. If the hydrogen were dissolved in the platinum the equilibrium concentrations would be the same in both cases. While it is probable that some hydrogen is dissolved in the platinum, it is difficult to tell how much because of the slowness in reaching equilibrium. If we start with a platinum black saturated with hydrogen, and burnish the platinum black without removing it from the hydrogen, any hydrogen which is set free will be adsorbed hydrogen, and a measurement of the amount will give some clue as to the relative amounts of dissolved and adsorbed hydrogen in the platinum. Similar experiments should also be made with palladium and hydrogen. If powdered alumina or other material is compressed to a solid mass in presence of an adsorbed gas, much of the adsorbed gas will be set free and none of the dissolved gas in case any is present. ( 9 ) ADSORPTION ISOTHERMS FOR MIXTURES O F GASES-In many cases the adsorption of one gas by a solid decreases the amount of a second gas which can be adsorbed; but there are no satisfactory quantitative measurements to show this.’ Adsorption isotherms should be determined, showing the relative amounts of two gases in the vapor phase and in the charcoal phase when in equilibrium a t constant pressure. (IO) BEHAVIOR OF MIXTURES OF CARBON BISULFIDE AND ILLUMINATING GAS WITH COCONUT CHARCOAL-According to Cabot, 8th Internal. Congr. Applied Chemistry, 12 (1912), 18. Sabin, “Technology of Paint and Varnish,” 1917, p. 201. 8 A m . Chem. J . , 46 (1911), 278; J . Fvank. Inst., 181 (1916). 845. 6 J . SOC.Dyers Colourists, 17 (1901), 294. 8 J . Frank. Inst., 174 (1912), 672. ’ Hempel and Vater, Z. Elektrochen , 18 (1912), 724 1
2
85
Matwin charcoal will take carbon bisulfide and carbonyl sulfide out of illuminating gas, one kilogram of charcoal cutting the sulfur content of I O cubic meters of gas to 2.92 g. Porous charcoals are the best, such as pine and linden. Bone-black takes up almost no carbon bisulfide, and coconut charcoal is said to be even less effective. This seems very remarkable because coconut charcoal adsorbs carbon bisulfide strongly. If the statement is correct, the illuminating gas must cut down the adsorption of carbon bisulfide very much. If carbon bisulfide and illuminating gas were adsorbed in the same ratio in which they occur in the mixture, an analysis of the gas coming through would show an apparent purification2 even though the total adsorption were very large. (11) DOES THE EFFECT O F A TEMPERATURE GRADIENT ON THE MOVEMENT O F SMOKE PARTICLES DEPEND ON THE NATURE O F THE SMOKE
PARTICLES
AND
OF
THE SURROUNDING
GAS?-
Aitkena has shown that a suspended smoke particle moves along a temperature gradient from the hotter to the colder portion. If this is due to the presence of an adsorbed gas film around the smoke particles, the phenomenon must vary quantitatively with the nature and physical state of the smoke particle and with the nature of the gas. As yet there are no experiments to prove this. (12) DO ELECTRICAL WAVES OR STRESSES HAVE A MEASURABLE
EFFECT ON THE ADSORPTION OF GASES?-schuster* pointed O U t that some of the most puzzling facts of the disruptive discharge admit of explanation if we assume the existence in contact with the electrode of a surface layer of condensed gas having a large inductive capacity. If the layer of adsorbed gas offers an increased resistance to the passage of an electrical discharge, it follows from the theorem of LeChatelier that an electrical stress will tend to remove the film of adsorbed gas. This enables us to account for many apparently unrelated facts in connection with over-voltage, with colliding drops, and with the electrolytic detector, the crystal detector, and the coherer as used in wireless telegraph^.^ While this point of view has proved useful, its accuracy has never been demonstrated experimentally It is very desirable that we should have experimental proof that electrical waves or stresses do decrease the adsorption of gases. (13) DECOMPOSITION OF SODIUM AMALGAM-FernekeSa found that alcohol and many other organic substances increased the rate of reaction between sodium amalgam and water. He accounts for the phenomenon by assuming the intermediate formation of hypothetical compounds between solvent and solute which are extremely unstable towards sodium amalgam and, therefore, react very rapidly with it. While this explanation may be right, it has not proved helpful and is, therefore, useless, a t any rate for the present. It seems probable that certain organic substances lower the over-voltage a t mercury, and consequently make the sodium amalgam unstable. This hypothesis is susceptible of proof by direct experiment. While there are no measurements as yet made under conditions strictly comparable to those in Fernekes’ experiments, Carrara? has shown that the over-voltages are quite different in methanol and in ethyl alcohol from, what they are in water. I have often wondered whether the rgason that nobody has ever prepared, electrolytically, a sodium alloy using a cathode of fused Wood’s alloy, might be because the over-voltage is not sufficient in this case. (14)FIXATION OF OXYGEN BY cARBoN-Rhead and Wheeler* discuss the adsorption of oxygen by carbon as follows: J . Gasbel., 62 (1909), 602. Cf.Leighton, J . Phys. Chcm., 20 (1916), 32. a Trans. Roy. SOC. Edinburgh, 32 (1884), 239; Bancroft, J . P h y s . Chem., 24 (1920), 421. 4 Phil. Mag., [ 5 ] 29 (1880), 197. 8 Bancroft, J . Phys. Chem., 20 (1916), 18, 402, 503. 6 I b i d . , 7 (1905), 611. 7 2.physik. Chem., 69 (1909), 75. 8 J. Chem. Soc., 103 (1913), 462. 1
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The experiments show that carbon, a t all temperatures up to goo' and probably above that temperature, has the power of pertinaciously retaining oxygen. This oxygen cannot be removed by exhaustion alone, but only by increasing the temperature of the carbon during exhaustion. When quickly released in this manner it appears, not as oxygen, but as carbon dioxide and carbon monoxide. The proportions in which it appears in these two oxides when completely removed depend on the temperature a t which the carbon has been heated during oxygen fixation. No physical explanation alone can account for this fixation of oxygen; but, in all probability, it is the outcome of a physicochemical attraction between oxygen and carbon. Physical, inasmuch as it seems hardly possible to assign any definite molecular formula to the complex formed, which, indeed, shows progressive variation in composition; chemical, in that no isolation of the complex can be effected by physical means. Decomposition of the complex by heat produces carbon dioxide and carbon monoxide. At a given temperature of decomposition these oxides make their appearance in a given ratio. Further, when a rapid stream of air a t a given temperature is passed over carbon (which has previously been "saturated" with oxygen a t that temperature) carbon dioxide and carbon monoxide appear in the products of combustion in nearly the same ratio as they do in the products of decomposition of the complex a t that temperature. Our hypothesis is that the first product of combustion of carbon is a loosely formed physicochemical complex, which can be regarded as an unstable compound of carbon and oxygen of an a t present unknown formula, C r O y : It is probable that no definite formula can be assigned to this complex.
It is perfectly possible that the mysterious oxide is a definite compound which is adsorbed by the charcoal and which, therefore, has a decomposition pressure1 which varies with varying temperature. On this hypothesis the pure compound, possibly CIZob, or a decomposition product,e perhaps a compounds CnO, would behave in one way when heated by ifself and quite differently when adsorbed by charcoal. Decomposition pressures and compositions should be determined for mellitic acid, the oxide CIZO,,and any other compound, oxalic acid for instance, which might conceivably break down to form a compound having the properties described by Rhead and Wheeler. First-class charcoal should then be impregnated with these substances and the experiments repeated. It is not necessary to assume that the compound breaks down in different ways a t different temperatures. There is always an excess of carbon present, and, on slow heating, one would probably always come very close to the equilibrium ratio for carbon dioxide, carbon monoxide, and carbon for the temperature in question. If a current of an inert gas were passed rapidly through the system so as to sweep out the decomposition products as fast as formed, it ought to be possible to approximate to the decomposition products which the compound would give if heated by itself. (Is) OXIDATION TEMPERATURE FOR CARBoN-The experinIentS of Manville4 on the oxidation of carbon were undoubtedly vitiated by the presence of hydrocarbons. These experiments should be repeated with charcoal which has been freed from hydrocarbons by treatment with steam. (16) SYNTHESIS OF MELLITIC Acrn-The experiments of Meyefl seem to show that pure carbon cannot be oxidized t o mellitic acid and that the mellitic acid obtained by the oxidation of ordinary wood charcoal is due to the oxidation of some hydrocarbon. To make the proof conclusive, it ought to be shown what hydrocarbons oxidize to mellitic acid under the conditions of the experiment. With our modern techriique, this should not be difficult. (d 7) DETERMINATION O F HEATS OF ADSORPTION-we have Bancroft, J . Phys. Chem., 24 (1920), 220. Diels and Wolf, Bev., 89 (1906), 689; Diels and Meyerheim, Ibid., 40 (1907), 355; Meyer and Steiner, I b i d . , 46 (1913), 813; Armstrong and Colegate, J . Sac. Chem. I n d , 32 (1913), 396. a Lowry and Hulett, J . A m . Chem. Sod., 42 (1920), 1408. J . chim. phys., 8 (1907), 297; Duhem, Van Bemmelen Gedenkboek, 1910, 1 ; Lowry and Hulett, J . A m . Chem. Soc., 43 (1920), 1408. 6 Monatsh., 86 (1914), 163. 1 2
Vol. 13, No.
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very few measurements on the heats of adsorption of gases,l and some of these are not very accurate. The subject is an important one2 and measurements should be made with great accuracy. The heats of adsorption of hydriodic acid and of hydrobromic acid by charcoal are several times the latent heat of vaporization, and we do not know a t all why the molecular heat of adsorption of hydrogen should be 18,000 calories with palladium and about 46,000 calories with platinum. CONTACT CATALYSIS
co ADSORPTION,
ETC., ON ADSORPTION OP HYDROGEN, ETHYLENE, ETC.-we know that carbon monoxide cuts down the catalytic action of platinum8 on hydrogen and ethylene, and we believe that this is because i t cuts down the adsorption of these gases; but there are no satisfactory quantitative measurements on the adsorption by platinum of mixtures of CO, with hydrogen or ethylene. Maxted' has made some measurements on hydrogen sulfide and hydrogen with palladium. (18) EFFECT OF
(19) ADSORPTION BY
COLLOIDAL PLATINUM O F SUBSTANCES
PEROXIDE-while we are quite certain that the poisoning of the platinum catalysis of hydrogen peroxide6 is due to the adsorption of the so-called poisons, there are not even qualitative experiments to prove this. Platinum black should be shaken with solutions of the different poisons and adsorption isotherms determined. WHICH POISON HYDROGEN
( 2 0 ) BEHAVIOR
OF POTASSIUM CYANIDE SOLUTION WITH COL-
PLATINUM, PLATINUM BLACK, AND MASSIVE PLATINUMBredige points out that when colloidal platinum is allowed to stand in contact with hydrogen peroxide and concentrated potassium cyanide, the platinum flocculates and precipitates. The agglomerated platinum causes the hydrogen peroxide to decompose, thus showing that the cyanide does not poison precipitated platinum black. There seem to be only two possible explanations. One is that the adsorption of potassium cyanide by platinum falls off very much more rapidly with increasing size of the platinum particles than the adsorption of hydrogen peroxide by platinum. The other explanation is that, through oxidation or otherwise, there is formed what might be called an anti-body, which cuts down the adsorption of the cyanide. Neither hypothesis is very satisfactory and there is no experimental evidence for either. This point should be cleared up. Kastle and Loevenhart' point out that prussic acid accelerates the decomposition of the hydrogen peroxide by iron and copper. There is no theory in regard to this. (2I ) APPARENT EQUILIBRIUM BETWEEN PHOSGENE AND AQUEOUS HYDROCRLORIC ACID-Phosgene reacts with water to give carbon dioxide and hydrochloric acid: COCla f HzO COz 2HCl So far as we know, this reaction is not reversible, and it actually runs to an end in presence of an excess of water. In presence of concentrated hydrochloric acid the rate of hydrolysis is practically negligible. The only way that I can see to account for this is by assuming that water and phosgene do not react by themselves and that the reaction takes place solely in contact with the walls of the containing vessel. When these are coated with a film of hydrochloric acid of sufficient concentration, no phosgene is adsorbed to speak of, and no reaction takes place. The hydrolysis should be studied with different concentrations of acid and with a varying ratio of wall surface to mass of solution. LOIDAL
+
1 Favre, Ann. chim. phys., [SI 1 (1874), 209; Masson, Proc. Roy. SOC., '74 (1904), 209; Dewar, P70c. Roy. Inst., 16 (1905), 183. 2 Lamb and Coolidge, J . A m . Chem. Soc., 42 (1920), 1146. * Lunge and Harbeck, 2. anoyg. Chem., 16 (1898), 5 0 . 4 J . Chem. Soc., 116 (1919), 1020. 6 Bredig and von Berneck, 2. physik. Chem , 31 (1899), 258; Bredig and Ikeda, Ibid., 37 (1901), 1 . 6 Z ahysik. Chem., 31 (18991, 332. 7 A m . Chem. J . , 29 (1903), 397.
Jan., 1921 (22)
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EFFECT O F OSCILLATING TEMPERATURES ON THE AP-
EQUILIBRIUM O F ETHYL BUTYRATE WITH LIPASE-Trichloromethyl chloroformate, ClCOzCCls, or superpalite as it has been called, decomposes to carbon tetrachloride and carbon dioxide in presence of alumina, ClCOaCCls = coz Cc4, and to phosgene in presence of ferric oxide, ClCOaCCls = 2coc12. The reverse reaction has never been made to take place to any measurable extent. Some superpalite and ferric oxide were placed in a glass tube connected with a closed manometer. There was rapid decomposition a t first, as shown by the increase in pressure; but, before long, the reaction came apparently to an end. On raising the temperature the reaction went a little farther and did not reverse when the temperature was brought. back to its original value. This experiment was not checked sufficientlyto make me willing to guarantee the results; but it looks as though the ferric oxide was poisoned and that when the temperature changed, more sdperpalite came in contact with the catalytic agent and was decomposed. If this is the true explanation, it suggests one interesting line of experimentation. When ethyl butyrate is treated with a small amount It of enzyme, the decomposition proceeds only a little way.’ seems probable that with an oscillating temperature it might be possible to carry the reaction much farther with the same amount of enzyme. (23) ACTION OF PLATINUM BLACK ON ACETIC ACID-Reiset and Millon2 state that acetic acid can be boiled with pumice without decomposition; but that it is decomposed completely if distilled from platinum black. They do not state what the decomposition products are. At first there might be enough oxygen in the platinum black to cause a n oxidation of the acetic acid; but that would soon come to an end. We are not absolutely certain that platinum black does decompose acetic acid catalytically a t the boiling point of the latter. If that does happen, we can only guess a t the reaction products. (24) CATALYSIS OF ETHYL ACETATE IN PRESENCE OF HYDROGEN -If a mixture of ethyl acetate vapor and hydrogen is passed over pulverulent nickel, it is probable that some or all of the initial products will be reduced before they have time to react in the normal way. A study of the reaction products should, therefore, throw light on the probable mechanism of the reaction which occurs in the absence of hydrogen. If methane and ethyl formate are the products, that would indicate that the original break had been into -CH8 and -COzCzH&. If acetic acid and ethane are found, they would probably be reduction products of CHL!02- and -CH2CH3. If the reaction products are methane, ethane, and either carbon dioxide or some of its reduction products, it would seem certain that ethyl acetate splits simultaneously into -CHs, -CHnCHa, and COZ. ( 2 5 ) CATALYSIS O F ETHER BY NICKEL-If ether is passed Over pulverulent nickel, one stage in the reaction will probably be to CHaCH20- and -CHzCHs or t o CzHbOCzHd- and -H. I n the first case the final products will be ethylene and water just as with alumina. I n the second case they are likely to be acetaldehyde, ethylene, and hydrogen, though the ethylene and hydrogen may combine more or less completely to form ethane. A study of this reaction should, therefore, throw light on the catalytic decomposition of alcohol by nickel. PARENT
+
(26) CATALYSIS OF METHYL FORMATE BY ALUMINA AND FERRIC
OXIDE-We have data for the catalytic decomposition of trichloromethyl chloroformate by alumina and by ferric oxide. As soon as we get the corresponding data for methyl formate, we shall be in a position to tell whether the substitution of hydrogen by chlorine changes the type of the reaction. 1
a
Kastle and Loevenhart, A m . Chem. J . , 24 (1900). 491. Comfit. rend., 16 (1843), 1190.
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(27) CATALYTIC ACTION OF FERROUS oxmE-Since alumina is very transparent and ferrous oxide very opaque to infra-red radiations, ferrous oxide should be much superior t o alumina as a catalytic agent, according t o the radiation theory of W. C. McLewis, in all cases where the formation of metallic iron or of another oxide did not interfere with its activity. (28) GUM ARABIC AS CATALYTIC AGENT-According to Tyndall,‘ gum arabic is practically opaque to infra-red rays. If this is SO, it must emit infra-red rays and should, according to the radiation theory, be a powerful catalytic agent for methyl acetate solutions. This would seem to be a crucial experiment. (29) ARSENIC POISONING OP THE GRILLO-SCHROEDER CONTACT MASS-The Grillo-Schroeder catalyst for the contact sulfuric acid process consists of platinum black precipitated in a certain way on magnesium sulfate. This contact mass is poisoned by arsenic just as is the platinized asbestos. It has been stated, however, that the Grillo-Schroeder catalyst can be regenerated by boiling with hydrochloric acid. It was supposed that the arsenic was removed as trichloride; but analysis showed that the regenerated contact mass contained a great deal of arsenic. The amount was said to be 3 per cent, but I do not know whether this was 3 per cent of the amount of platinum or of the contact mass. This arsenic must either have agglomerated, so that it no longer coated the platinum, or it must have reacted with the magnesium sulfate. It might be very difficult to tell from a microscopic examination what had happened, so that it probably would be better to study first the behavior of arsenic with porous magnesium sulfate in the absence of platinum. (30) SPONTANEOUS COMBUSTION OF OILED mGs-It is known that oiled rags will take fire spontaneously, and there issomeliterature on the subject.2 In view of the number of fires which seem to be due to this cause, somebody ought to develop a really first-class lecture or laboratory experiment tc illustrate this, and the experiment should be included in every introductory course in chemistry. (31) IGNITION TEMPERATURE O F GAS MrxTuREs-When gas mixtures are exploded by an incandescent wire or by a spark,a it seems probable that the nature of the wire or of the electrode has a catalytic effect, a t any rate a t the outset. If this is the case, it should be possible to poison the wire to some extent. Presence of carbon monoxide might perhaps change the apparent ignition temperature for oxyhydrogen gas. Something of this sort might account for the change in temperature when the mixture is diluted with one of the constituents and for the effect of sparks which do pot cause explosion. (32) DECOMPOSITION OF VERMILION BY CoPPER-De la Rue4 states that electroplated copper blocks cause vermilion to blacken, while cast copper does not. If this is true, the difference must be due to the greater porosity of the electroplated copper. The matter should be tested, so that we may know the facts. ADSORPTION O F VAPOR BY LIQUID
(33) COALESCENCE
OF
COLLIDING
DROPS
OF
DIFFERENT
LIQUIDS-Lord Rayleigh6 has shown that colliding drops or jets of water do not necessarily unite. This is because of a film of adsorbed air which prevents the drops from coming actually in contact. This phenomenon must be general, and must be most marked the greater the adsorption of gas by the liquid drops. Experiments should, therefore, be made with drops of nonaqueous liquids and in different atmospheres. It has also “Fragments of Science,” “Radiant Heat and Its Relations.” Galletly, Chem. Zentr., 1878, 543; Coleman, J . Chem. SOC.,94 (1878), 259; Kissling, Z. angew. Chem., 1895, 44; Lippert, Ibid., 1897, 434. 8 Roszkowski, Z . physik. Chem., 7 (1896), 485; Coward, Cooper and Warburton, J . Chem. Soc., 101 (1912), 2278; Parker, Ibid., 105 (1914), 1002; Sartry, Ibid., 109 (1916), 523; McDavid, Ibid., 111 (1917), 1003; White and Price, Ibid., 116 (1919), 1462: Thornton, Proc. Roy. Soc., 90A (1914), 272; 91A (1914), 17; 92A (1915), 9, 381; Phil. Mag., [6]98 (1919), 613. p Mem. Ch8m. SOL,2 (1845), 305. 6 P70C. Roy. Soc., 28, 406; 29 (1879), 71; 94 (1882). 130: Bancroft, J . Phys. Chem., 20 (1916), 1 . 1 2
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been shows by Lord Rayleigh’ and otherse that an applied potential difference of about two volts &ll cause colliding drops to coalesce; but this value has not been determined accurately, and we do not know how i t would vary, if a t all, with solutions instead oE so-called pure water. Both- these matters should be studied. (34) STUDY OF ORNDORFF AND CARRELL’S EXPERIMENTS ON AIRBuBBLmG-In some experiments with the air-bubbling method of determining molecular weights, Orndorff and Carrel13 found that with urethane solutions approximately theoretical values were obtained even when the rate of bubbling was varied a great deal. With urea solutions there is a distinct tendency for the apparent molecular weight t o go up as the rate of bubbling is increased. With phenol the apparent molecular weights were low a t all rates of bubbling and did not vary much with the rate of bubbling. The experiments of Campbell4 make it probable that some of the errors in the air-bubbling method are due to the presence of an adsorbed gas film on the surface of the liquid. The experiments of Orndorff and Carrel1 should be repeated, amplified, and studied with special reference to the work of Campbell. These same solutions might well be tried in No. 33. (35) SFFECT O F POWDERS I N MAKING DROPS coALEscE-Lord Rayleighs found that dry powders had a marked effect in causing colliding drops or jets of water to coalesce. whereas most of the powders were ineffective when wetted. No explanation was given for the phenomenon and yet one should be found. It is possible that the electrification of the powders may be a factor. Hardy6 has noticed that powders floating on a liquid sometimes move in the opposite direction from the same powders when submerged. ADSORPTION O F LIQUID BY SOLID
( 3 6 ) ABNORMAL DENSITY OF POWDERS I N LIQUIDS-Rose’
claims that platinum in the state of foil has a specific gravity of 2 1 to 2 2 , while a value of about 26 was obtained for platinum sponge precipitated from the chloride by sodium carbonate and sugar. This can be accounted for if we assume that the powders is not weighed alone in water, but in conjunction with a film of condensed water. Similar, though less extreme differences were obtained with gold, silver, and baripm sulfate. These experiments should be repeated and extended. (37) SYSTEMATIC STUDY O F RELATIVE WETTING, WITH SPECIAL REFERENCE TO FLOTATION AND TO ZERO FLUIDITY-NO systematic study of the selective adsorption of liquids by solids seems to have been made. There are a few scattered data. We know that kerosene will displace water in contact with metals, and that water will displace kerosene in contact with quartz,O while alcohol will displace oil in contact with meta1,lO and linseed oil11 will displace water in contact with white lead. When making lithographic inks, oil is added to the wet paste and the water is ground out. There are only a few quantitative measurements‘2 on the selectiye adsorption of a liquid by a solid. A careful systematic study of the phenomenon should be made. I t is the determining factor in ore flotation. If we get zero fluidity’s when the voids in a powder are just filled withliquid, PYOC. R o y . Soc., 29 (18791, 7 1 Newall, Phil. M a g , [ 5 ] 20 (1885), 31; Burton and Wiegand, I b i d . , 23 (1912), 148. 8 J . Phys Chem., 1 (1897), 753. 4 Trans. Faraday Soc., 10 (1915), 197. 5 Pvoc. R o y . Soc , 34 (1882), 130; Bancroft, J.Phys.Chem.,20 (1916), 14. 6 Pvoc R o y SOC., 86A (1912), 609. 7 P o g g A n n , 73 (1848), 1; J . Chem. Soc., 1 (1849), 182. 8 See, however, Johnston and Adamq, J. A m . Chem. SOC., 34 (1912), 563. 8 Hofrnann, 2. physik. Chem., 83 (1913), 385. 10 Pockels. Wied A n n , 67 (1899), 669. 11 Cruickshank Smith, “The Manufacture of Paint,” 1915, p. 92. 1) Graham, J . Chem. Soc , 20 (1867). 275; Mathers, Trans A m . Elecfrochem. S o c , 31 (1917), 271. ‘iBingham, A m . Chem J., 46 (1911), 278; J . Prank. Inst., 181 (1916), 1 2
845.
Vol. 13, No.
I
the extra liquid is present as an adsorbed film and the determination of the amount is very important. (38) BEHAVIOR OF GUM ARABIC WITH ALCOHOL AND WATERIt is not very easy to peptize gum arabic by grinding with water because the water does not displace the air readily from the gum. If the gum is ground for a moment with alcohol, water then wets i t readily. This is surprising because water peptizes the gum and alcohol does not; one would consequently have expected the water to be adsorbed more strongly than the alcohol. By shaking the gum arabic with aqueous alcohol, it should be an easy matter to tell whether the alcohol or the water is adsorbed the more strongly. It is possible that there may be a film of grease on the gum which is removed by the alcohol. It is possible that alcohol displaces the air more rapidly because it adsorbs the air more strongly than does water. If that is the case, alcohol should show a special behavior as colliding drops in No. 33. Experiments should be made with acetone, acetic acid, glycerol, etc., so as to see to what extent the phenomenon is general or to what extent it is peculiar to alcohol. We are always working up to the problem of why concentrated sulfuric acid wets sulfur trioxide more readily than water does. (39) BEHAVIOR O F MERCURY 18 GLASS CAPILLARY A S AIR IS REMOVED-MerCUry does not wet glass because air is adsorbed more strongly than mercury by glass. According to this point of view, mercury should wet glass if the air is removed completely. There are experiments by Hulett and others to show that this is true; but the problem has never been handled in a clear-cut manner. One would like to see mercury made to rise in an evacuated glass capillary. (40) CARRYING O F MERCURY ON IRON GAUZE-Lord Rayleighl pressed a piece of iron gauze down on the flat bottom of a glass vessel holding a shallow layer of mercury, and found that the gauze remained on the bottom of the vessel and did not rise through the mercury. The reason for this is that the mercury does not wet the iron. A corollary from this, which has not been tested experimentally, is that one should be able to carry mercury in an iron sieve just as one can carry water in an oiled sieve.2 Since sodium amalgam wets iron,s a dilute sodium amalgam should run through an iron sieve which would stop pure mercury. Also Rayleigh’s experiment should not succeed if a sodium amalgam were substituted for mercury. All these predictions should be confirmed or disproved experimentally. (41) PRESSURES DUE TO SELECTIVE WETTING-when Water displaces air a t the surface of a solid, one wonders how much pressure might be developed. Jamin4 has made some preliminary experiments along this line. A hole was bored in a piece of dried chalk. Into this hole was dipped one end of a manometer, and the hole was then clo.;ed. When the chalk was placed in water, the air was displaced from the pores and a pressure of 3 t o 4 atmospheres was obtained. This is not the maximum pressure because the amount of dead space in the manometer, was large. A better method would be to determine the pressure necessary for the air to force the water out of the pores of the chalk. It would also be interesting t o substitute alcohol and other liquids for water. By filling a porous block of silica with kerosene and placing it in water, or by filling a porous block of lead or zinc sulfide with water and putting it in oil, one could measure pressures which might be of distinct interest in their bearing on flotation and on oil deposits near the sea. (42) CONSTANT-TEMPERATURE BATHS-MCIntOSh and Edsons have frozen aqueous salt solutions in a mixture of ether and 1
S c i e n t d c P a p n s , 4 (1903), 430.
Chwolson, “Trait6 de Physique,” 1, 111 (1907), 613. a J . Chem Soc., 26 (1873), 418. 4 Chwolcon, ‘Trait6 de Physique,” 1, 111 (1907), 622 6 J A m Chem Soc., 38 (1916), 613. 2
Jan.,1921
TBE J O L - R X A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
solid carbon dioxide. The solid mass is said to melt a t a constant temperature, that of the initial freezing point of the solution. ’ At present there is no theoretical explanation for this. (43) THEORYOF ADHESIVES-The whole theory of adhesives depends in part on the fact that the cementing material adheres strongly t o the two surfaces and hardens there. It is therefore possible that one agglutinant may be useful for a number of differerit materials, such as wood, glass, metal, ivory, etc.,‘ while others give good results only with special materials. Since the books give different recipes for cements for glass, cements for metals, cements for metals and glass, etc., the differences in adsorption are real ones, though no one has ever made a careful study of agglutinants from this point of view. Some-
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body should study the different adhesives from this point of view. (44) VEGETABLE GLUES-There js practically no literature on the vegetable glues outside of a few patents. We need published research on the whole subject with special reference to peptization, viscosity, and adsorption. (45) WATERPROOF GLUES-A waterproof glue of indefinite life is needed. Our large timber is disappearing fast and, before long, we shall be compelled to build up large pieces by gluing together what we can get from small stuff. At present the best waterproof glues weaken in time, no doubt because of the action of water on the protein material. A glue should be made that will not take up moisture after i t has once dried. (Tobe continued)
SCIENTIFIC SOCIETIES CROP PROTECTION INSTITUTE DISCUSSES WAR ON BOLL-WEEVIL
*
A meeting of the Crop Protection Institute, recently organized under the National Research Council and made up of growers, scientists, and business men, was held a t Rumford Hall, New York City, on Monday, December 6, 1920. The principal topic for discussi’on was the control of the boll-weevil by the application of calcium arsenate. Cotton growers have suffered great losses in recent years due to the ravages of the boll-weevil, and although the Department of Agriculture has worked out careful methods for combating this pest by the use of calcium arsenate, the results have not always been satisfactory owing to faulty technique in the application of this chemical. The attendance was made up of representatives of insecticide manufacturers and of manufacturers of spraying machinery, as well as the regular membership of the Institute. Prof. €3. C. Coad of the U. S. Agricultural Experiment Station at Tallulah, La., who has done a great deal of work on the control of the boll-weevil, presented a two-reel moving picture entitled “Goodbye, Boll-Weevil” which demonstrated the complete control that can be won over the insect by the proper use of calcium arsenate with the right kind of machinery. Professor Coad stated very plainly that there had been considerable failure in the application of calcium arsenate in the hands of persons who had been improperly informed on the method of using it. He summed up the causes of failure as being due to laxness in carrying out definitive instructions, bad chemicals, and misinformation passed on to the farmer by ignorant salesmen. H e also commented on the fact that many of the dusting machines sold to users were inefficient. In 1920, IO,OOO,OOO Ibs. of calcium arsenate had been sold t o the South, said Dr. Coad, but probably 5,000,ooo Ibs. remained unused, owing t o lack of results in many cases. At one of the meetings of the scientists connected with the Institute the problems involved in the production and use of calcium arsenate were discussed at some length. The general feeling was that a standard for total arsenic in commercial calcium arsenate be prescribed and adhered to. The standard which seemed most desirable was 40 to 42 per cent total arsenic. In the discussion i t was brought out that from five to seven times the present annual consumption of arsenic in the United States would be required for the control of the boll-weevil alone. The fact that about 115 scientific men and 23 commercial concerns have already joined the Crop Protection Institute and that the first real business meeting was so well attended augurs we3 for its future. It was disappointing, however, t o the organizers to be informed by Dr. I,. 0. Howard in his address that the scientists of the Federal Government did not
see their way clear to become members of the Institute even though they sympathized with its purposes. Although the constitution provides for the control of the Institute by the scientist members only, the government men feel that it would not be proper t o become actively identified with an organization, the funds of which come largely from commercial sources.
AMERICAN INSTITUTE OF CHEMlCAL ENGINEERS The Thirteenth Annual Meeting of the American Institute of Chemical Engineers was held in New Orleans, December 6 t o 9, 1920. The meeting was held in New Orleans in order to give opportunity to make a study of the characteristic industries of,this section of the South. The program provided for a stay of two and one-half days in New Orleans, a two-day trip through the sulfur, salt, rice, and sugar region of the state of Louisiana, and stops on the return trip at Chattanooga, Tenn., Roanoke, Va., and Luray, Va. Arrangements had been made at all points visited for inspection of the local industries. The program of papers contained several which were descriptive of the local chemical industries. Dr. R. F. Bacon presented a paper on “Recent Advances in the American Sulfur Industry” in which he discussed the difficulty encountered in burning Louisiana sulfur on account of the presence of small amounts of petroleum. Lezin A. Becnel presented a paper on “Operating Variations in Sugar Production as Indicated by Some Plantation Data,” in which the author gave the results of a study of the production of sugar and sirup during a period of some 40 yrs., and contended that the greatest profits would be made by producing either sugar or sirup, or both, according to the market for each product. The paper was discussed by Professors Chas. S. Williamson, Jr., of Tulane University, and Chas. E. Coates, dean of the Audubon Sugar SchooI. A very interesting talk on the “Resources of the State of Louisiana” was given by Mr. N I,. Alexander, chief of the State Conservation Commission. Motion pictures of the extensive state game preserves were shown. Mr. Alexander also described very successful experiments in reforestation. It has been demonstrated that timber suitable for wood pulp can be grown in Louisiana in 15 yrs. George G. Earle, chief engineer and superintendent of the Sewerage and Water Board, described the sewage, water purification, and drainage systems of New Orleans. Particular interest was shown in the low lift pumps used t o raise the storm waters and sewage of New Orleans torthe level of the water courses used for drainage. The other papers presented were of a general chemical engineering character. Most of them were fully illustrated by lantern s 1ides and were very fully discussed. They included:
