IAVDUXTRIAL AND ENGINEERING CHEMISTRY
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given volume, and there exist numerous voids, partly caused by the destruction of various glands. The grain layer, then, contains less collagen per unit of volume than does the flesh layer. The emulsion of sulfonated oil in water is an exceedingly fine-gained one; even under a high-power microscope no individual droplets can be distinguished. Let us assume that this fine-grained emulsion can penetrate the grain and flesh surfaces with equal ease, the size of the openings in each surface being enormous compared to the diameter of the droplets. The result will be that both the grain and flesh layers will receive the same quantity of oil per unit volume of skin, but as the density of the grain layer is less than that of the flesh, the grain layer will receive more oil per unit weight of skin. This, as we have seen, is the case in practice, when skin is fat-liquored with sulfonated oil alone.
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The addition of egg to the sulfonated-oil emulsion causes an enormous increase in the size of the droplets. Let us suppose that these larger dropleta, or some of them, have difficulty in penetrating the small openings in the grain surface. The result will be that, in a limited time and in the presence of a limited quantity of oil, more oil will be taken up by the flesh layer and less by the grain. This is exactly what happens when skins are fat-liquored with sulfonated oil-egg mixtures. Acknowledgment The author wishes to express his sincere thanks to John Arthur Wilson, under whose direction these studies of fatliquoring were inaugurated, and to John Behnke for laboratory assistance.
Pumice Impregnated with Anhydrous Magnesium Perchlorate as a Drying Agent' John H. Yoe, Randolph W. McGahey, and William T. Smith UNIVERSITYOF VIRGINIA, UNIVERSITY, VA.
EVERAL years ago Willard and Smith2 discovered that anhydrous magnesium perchlorate is a highly efficient drying agent, being as active (at low rates of flow-1.5 to 3.5 liters per hour) as phosphorus pentoxide and having a capacity several times greater. I n addition to possessing high activity and large capacity, anhydrous magnesium perchlorate has a number of other advantages over phosphorus pentoxide: (1) It can be easily and repeatedly reactivated; (2) it does not become sticky upon handling; (3) it does not form channels through use; (4) it contracts in volume upon absorbing moisture; and ( 5 ) being neutral, it can be used as a drying agent for many substances for which phosphorus pentoxide or concentrated sulfuric acid are not permissible. In fact, aside from the relatively high cost, anhydrous magnesium perchlorate seems to be about the best all-round drying agent at present available. Willard and Smith2have also shown that magnesium perchlorate trihydrate at 0' C., and a t rates of flow up t o 5 liters per hour, is as effective as a drying agent as phosphorus pentoxide and anhydrous magnesium perchlorate, but that at higher rates of flow the efficiency, although still high, falls off rapidly.
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Note-A specially prepared magnesium perchlorate trihydrate (Smith) may be obtained in the market under the trade name "Dehydrite" and is highly recommended for use as a water absorbent in steel and organic combustion analysis, and for drying gases. The preparation and use of magnesium perchlorate and other alkaline earth metal perchlorates in various forms have been covered by patent application by G. F. Smith.
During the World War one of the authors (Yoe) tested the efficiency of a number of desiccants for use in gas-mask canisters. I n some cases the desiccants were impregnated in granules of pumice, with the view to increasing the surface of a given weight of drying agent and to give a more rigid product. It occurred to the authors that anhydrous magnesium perchlorate impregnated in small lumps of pumice (porous brick, asbestos, etc.) should be a very effective and convenient drying agent and might be cheaper than the pure anhydrous salt. A series of experiments3 has been Received January 9, 1928. Contribution No. 44. J . Am. Chem. Soc., 44, 2255 (1922); see also Smith, Brown, and Ross, IND.ENG.CHEM.,16, 20 (1924); Yoe, Chem. News, 130, 340 (1925); Lee and Brown, J . B i d Cheht ,75, 69 (1927) 8 These experiments were completed in 1925 but publication was withheld in the hope of extending the investigation. 1 2
made to determine the drying efficiency of anhydrous magnesium perchlorate impregnated in granules of pumice. The results are recorded in this paper. Materials
A 35 per cent solution of magnesium perchlorate was prepared by adding the theoretical amount of perchloric acid to pure magnesium oxide. Pumice granules, 10 to 20 mesh (20 to 30 mesh in one case), were then placed in the magnesium perchlorate solution and allowed to soak 24 hours, after which the pumice was removed, the excess of solution drained off, and the granules heated on a hot plate at about 175' C. until the perchlorate particles were dehydrated. The granules were than placed in a large Pyrex glass tube, slightly inclined, and heated at about 240' C. while a slow current of dry (P205) air was drawn through the tube. The heating was continued until a weighed PzOs U-tube placed just beyond the drying tube showed no gain in weight after several liters of air had been drawn through. The pumice granules thus impregnated with anhydrous magnesium perchlorate were removed from the drying tube and gently and uniformly packed in a U-tube while still hot. The U-tube was fitted with ground-glass stoppers and a small side tube a t the top of each arm. The %tube was 1.5 cm. in diameter and a 5-em. column (unless otherwise stated) of drying agent was used. Before adding the drying agent, the U-tube was filled around the bend with dry pumice granules and the 5-cm. column of drier was always put in the vertical portion of the tube, the left arm or entrance side being used. Apparatus
The apparatus consisted of the following, connected in series in the order named: (I) glass capillary flowmeter; (2) two Liebig potash bulbs containing water; (3) U-tube containing the drier; (4) Pz05U-tube (moisture detector); ( 5 ) P20s U-tube (protector); (6) aspirator bottle. All connections were made with strong rubber tubing, care being taken to place the ends of the glass tubing as close together as possible. A small plug of glass wool was inserted just beyond the second potash bulb to prevent any spray from being carried over into the magnesium perchlorate tube. The second P205tube was inserted to guard against moisture
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ISDUSTRIAL A S D ESGI.VEERIil'G CHEMISTRY
diffusing back from the aspirator into the P20stube serving as a moisture detector. The potash bulbs and U-tube containing the drier were immersed (up to their outlet tubes) in a water bath maintained a t 25.0 * 0.1" C. The thermometer was checked a t 25" C. against a standard thermometer. Experimental The drier tube and P205tube were each weighed by counterpoise against similar tubes before being connected in the set-up, and the apparatus was then tested to make certain of no leaks. The potash bulbs (saturators) and U-tube containing the drier were allowed to stand in the thermostat until their temperature was 25" C. A current of air was then drawn through the apparatus a t the rate of 2 liters per hour. The flowmeter was not used t o measure the rate of flow after the first one or two runs, since it was found that a fairly uniform rate could be maintained by observing the rate of flow of water from the aspirator bottle, and with the advantage that the apparatus upon stopping the air current reached a pressure equilibrium much more quickly than it would with the flowmeter in series. The exact volume of air drawn through the apparatus was obtained by measuring the water from the aspirator in a volumetric flask, the time required to fill the flask being noted. From time to time the air current mas stopped, and the drier tube and first PzOj tube were weighed (by counterpoise). After the P20j tube shoTved the first gain in weight, the run was continued a while and then final weights on the drier tube and P206tube were obtained. The results are recorded in the acconipany-
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ing table. The average per cent saturation of the air during the runs was about 95 a t 25" C., as calculated from the increase in weight of the absorption tubes per measured volume of air drawn through them. Pumice-Mg(ClO& Granules Used in Desiccator Twenty-one grams of the 10- to 20-mesh granules of pumice impregnated with anhydrous magnesium perchlorate were placed in an ordinary desiccator and used in obtaining the constant weights of porcelain, silica, and platinum crucibles. In each case the crucible was heated over the blast lamp 10 minutes, cooled in the desiccator 20 minutes, weighed, reheated 10 minutes, etc. All meighings after the first 10 minutes' heating showed constant weights of the crucibles. HEIGHT WEIGHT OFABOF
MgR U N (C10dza Grams 1 1.87
SORBENT
Experimental Results TOTALAIR WATER SIZE D R A W N AB-
UMN
THROUGH GRAN- APPAULES RATUS
Cm. 5
Mesh 10-20
COL-
SORBED
OF
BY
DRIER Grams 0.0424 0.5924 0.8167 1,1082 1.2520 0.2038 0.5574 0.9080
Lilevs 2 27 37 50
2
60 10 28 46 49 1.25 30 10-20 10 20 25 2.46 5 20-30 10 20 30 Weight of Mg(C10d)z impregnated in 2.64
3 4 0
5
10-20
...
WATER RATIO UNAB- WT. Hz0 SORBED ___BY Wt. MgDRIER (clo4)z Gram 0.0000 0.0000 0.32 0.0003 0.44 0.0018 0.59 0.0816 0.0000 0.0000 0.21 0.0028 0.34 0.0031
0.2112 0.0000 0.4198 0.0000 0.4652 0.0645 0.2082 0,0000 0.4268 0.0000 0.6614 0.0032 absorbent granules.
0.34
0.18 0.26
Changes in the Chemical Industry during the Past Twenty-five Years' Anna Hazel Swift CHEMICAL DIVISIOS,BUREAUO F FOREIGS A N D DOXESTIC COMMERCE, WASHINGTON, D.
HE American chemical industry has developed from a position of minor to major n-orld importance during the past twenty-five years. ,4t present the United States possesses the largest chemical industry in the world. Its production exceeds $2,275,000,000 and over 90 per cent of its consumption is of domestic origin. A yital factor in this deyelopment is the increasing cooperation between science with a creative vision and aggressive courageous capital. A rapid expansion in other large domestic manufacturing industries, which are large consumers of chemicals for the fulfilment of the diversified demands of an increased population, is a cause contributory to the growth of the chemical business. The prosperous condition of the majority of the inhabitants, with a greater purchasing power, created a new market for many of the higher processed fine chemicals, the productions of the medicinal, pharmaceutical, and toilet preparations industries. The term "chemicals and allied products" may have a very limited or equally broad meaning. I n this discussion it is used to include naval stores, pigments, paints and varnishes, crude drugs, essential oils, linseed and China wood oils, beeswax and other animal and vegetable waxes, medicinal, pharmaceutical, and toilet preparations, industrial chemicals, explosives, matches, pyroxylin products, fertilizers, and coal-tar products. The world changes almost overnight and a thriving industry of today may be on the wane tomorrow. This is par* Received March 16, 1928.
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c.
ticularly true of many branches of the chemical industry and the scientist must watch the new products of competitors at home and abroad and consider the possible effects on his pet and private specialties. The sodium nitrate industry is an excellent example of this. Recall the consternation caused by the first commercial production of synthetic sodium nitrate in Germany with the subsequent effect on the longestablished Chilean nitrate industry. A scientist must also be prepared, not only to fight for the existence and continued use of his commodities, but also to develop new uses for them. He cannot afford to lose an opportunity for the creation of new commodities, neither can he overlook the possibilities of the development of newer and cheaper methods of manufacture of the already successful articles. As the result of price and t h e dependency upon foreign countries for many ram materials, new substitute commodities are often brought into commercial existence. The growth of the rayon industry, founded upon chemical processes, illustrates this point. Frequently the element of time forces the manufacturer and consumer to seek substitutes. It \vas chiefly the result of the length of time involved to complete a satisfactory varnish job that cellulose-base lacquers came into importance. The quick method of application, the short time required in drying, and the beautiful colors assured their prompt popularity. There is a greater field than eve; before for scientists with
