858
INDUSTRIAL AND ENGINEERING CHEMISTRY
total volume. Yet smaller spheres may be added to occupy part of the 26 per cent of voids. Still smaller ones added to these will further help to fill voids. Why not apply this principle in making a thin paper more opaque? If different sizes of appropriately graded clay filler were added, more clay could be carried in a given volume, thus making a denser paper. Of course, any clay filler is made up of mixed sizes, but some study of the most effective differences in size should be worth while. The same reasoning applies to the manufacture of a paint of maximum hiding power. Many other possible developments of industry along colloidal lines could be mentioned. A factory waste suspended in water might be precipitated by formation of countless minute air bubbles. Adsorption films should form a t the bubble-water interface. Added salts might aid this partial coagulation. The de-inking of old newspapers (7000 tons wasted daily) by loosen-
Vol. 15, No. 8
ing the carbon black with dilute alkali and then adsorbing the carbon on a colloidal clay such as bentonite, which carries the black right through a paper filter, is an assured success, according to the United States Forest Products Laboratory. Saklatwallas proposes adsorption of gases on metals as a criterion of corrosion. He notes the fact that the metals least corroded-such as platinum, palladium, and tungsten-are the ones that can adsorb large volumes of gases. Fundamental properties of colloidal systems must be studied first. Applications will follow readily enough. Colloid fellowships would greatly aid in increksing our knowledge of these fundamentals and also serve to train men who could apply these principles to the industries. Such fellowships could be supported by a single company interested in contributing its share to the common fund of knowledge, or by a group of industries. 8
Chem. Met. Eng., 27, 647 (1922).
Safety and Efficiency in the Chemical Industry’ By L. A. DeBlois2 E. I.
DU P O N T DE
NEMOURS & CO.,
B
EFORE attempting to establish the relation of safety to efficiency in any industry, or in industry as a whole, we must definefhe terms and compare the basis of measurement. The occurrence of accidents, either their number (frequency) or their extent (severity), is the index, not of safety, but of its reciprocal, the hazard. The basis of measurement is exposure, expressed either as man-hours (payroll-hours) or, where the number of hours of exposure per day is practically constant or where a statistical day is assumed, simply as men. The precise form in which the basis is applied is immaterialwhat we should keep in mind is that it expresses human exposure to accident. RELATION BETWEEN SAFETY AND
EFFICIENCY
The index of efficiency in the engineering sense is output, and the base, input, both being expressed in the same units. I n industry these units are always material-so many thousand bottles, or so many tons of castings-but never so many thousand human beings, or so many thousand payroll-hours. Obviously, then, we cannot directly compare safety and efficiency, since we do not measure them by the same yardstick. We do, however, express output as so much production per man, and this we may compare with accident occurrence since both are calculated on the basis of exposure (man-hours). We all know that output depends upon the mental and physical equipment of the individual worker, the mechanical equipment furnished him for doing his work, upon the condition of these three forms of equipment, and upon the skill and energy with which he employs them. So also with accident preventionit depends upon mental, physical, and mechanical equipment, and upon the degree to which it is successfully applied by the individual. The degree to which any given equipment is successfully applied to its purpose is in a general sense its efficiency, and so we may write down that both output and safety depend upon the mental and physical efficiency of the worker and upon the mechanical efficiency of his working equipment. If we increase any one of these we shall expect to find a simultaneous increase in output and safety, provided that which we term “efficiency” is in each case true efficiency. Presented before the Division of Industrial 1 Received March 24, 1923. and Engineering Chemistry at the 65th Meeting of the American Chemical Society, New Haven, Conn., April 2 to 7 , 1923. 2 Manager, Safety Division, Service Department.
WILMINGTON,
DEL.
As illustration let us consider the handling of acid in carboys in comparison with the use of tank cars. The carboy method is mechanically less efficient because of higher acid losses. These arise principally from ( a ) overflow or leakage while filling, ( b ) breakage or leakage in transportation, (c) leakage or loss while emptying, ( d ) acid residue after emptying. There are also evaporation losses which are probably not material with proper stoppering. With tank cars there are corresponding possibilities of loss, but if the equipment is given inspection and repair commensurate with the value of the container and its contents, the total losses per unit of acid handled are actually less. I n the matter of injury occurrence, the use of carboys is much more hazardous than the use of tank cars. Men are apt to be burned if carboys overflow while filling, or if they break, or if they are emptied carelessly, or if they contain a small amount of acid when thought to be empty. It is true, if a tank car starts a leak its entire contents may be lost, but such leaks are infinitely less frequent than instances of carboys breaking, and after all it is generally the first contact with acid rather than the total amount of acid liberated that is associated with the injury. However this may be, the interesting point is that the mechanical conditions which cause losses and lower the mechanical efficiency of the process are exactly the same conditions which cause injuries to the workers. EXTRA HAZARDS IN CHEMICAL INDUSTRY Each material handled in industry has its own potentiality for causing accidents-heavy materials crush by their weight, sharp materials cut or abrase, hot materials burn or scald-but in the chemical industry we encounter materials with additional properties-for example, materials such as acids and caustics which, though cold, cause burns; materials which give off corrosive, suffocating, or toxic vapors; materials which poison through the unbroken skin; materials subject to sudden and perhaps violent decomposition, etc. So also with the processes in which the materials are employed; they have the common mechanical hazards inherent to a mechanical process plus additional hazards introduced by the presence of materials with extrahazardous characteristics. By way of illustration, we may think of a workman whose eye is struck by a particle thrown from the basket of a centrifugal wringer. Ordinarily, the rwult is a slight abrasion of the cornea, but if the particle is caustic
August, 1923
INDUSTRIAL A N D ENGINEERING CHEMISTRY
the abrasion is complicated by a caustic burn. One readily sees, then, that the accident hazards of the chemical industry should be intrinsically greater than those of general industry. It is natural that the chemical industry should have acquired the reputqtion of being inherently hazardous, and we will grant that accidents a t many chemical plants have been frequent and often severe, and that the materials themselves and therefore the processes in which they are involved may be more hazardous than other corresponding industrial processes not employing hazardous materials. This may be the case, however, without the industry itself or any typical plant of the industry being “inherently” hazardous in the sense that the extra hazards cannot be obviated. We have already seen that safety is dependent, not alone on mechanical efficiency, but upon mental and physical efficiency as well, and in the well-regulated chemical plant a wholesome respect for the accident-causing properties of the materials being handled may quite offset the extra hazards of the materials themselves-in other words, the greater material hazards are balanced by higher m’ental and physical efficiency in the organization. To accomplish this employees need not be necessarily higher paid or of higher mental caliber, but they must a t least be carefully instIucted in the hazards of the processes as well as in their regular duties. Furthermore, they must be carefully supervised in their work. The motto of a chemical plant must be literally “Safety First,” not set forth as a mere bulletin board slogan, but as a working precept in which the plant management devoutly believes. When such question arises safety must actually take precedence over production and quality, for if safety is sacrificed both production efficiency and quality efficiency will suffer. No plant manager need fear to enunciate the principle of “Safety First.”
.859
many chemical plants cannot be termed “well established,” because processes are constantly being altered and more or less temporary or makeshift equipment is in daily use. Furthermore, there constantly arises the necessity of employing what might be called “emergency methods”-methods not followed in regular and standardized operating practice, but evolved on the spur of the moment either after breakdown or other stoppage of operations through unforeseen circumstances or upon starting up a new operation. In the Dye Works of the du Pont Company during 1922, sixty per cent of the injury severity rate was due to such emergency methods. For its interest in this connection the following is quoted from instructions sent out by the Works Safety Committee: The use of “emergency methods” is a t present unavoidable and this Committee, recognizing this fact, desires to secure your cooperation in minimizing the dangers of their employment. In view of the fact that these methods are evolved under stress, the Committee wishes that checks of the following nature be considered: (1) Responsibility for use of emergency methods be clearly placed on supervisors and foremen-i.e., use of these methods must have their O . K . (2) Someone in a supervisory capacity should be present until difficulties have been overcome and operation is moving normally or has been shut down safely. (3) Great care should be taken to thoroughly protect, by means of goggles, gloves, etc., all men working under emergency conditions. One reads in such injunctions the result of close scrutiny of working conditions and a n evident indication of practical rather than emotional efforts to prevent accidents. N E E D OF P L A N T
DISCIPLINE
Discipline in a chemical plant must be strictly maintained, COMPARIE~ON OF ACCIDENTRECORDS OF CHEMICALAND hToh-- for in no other industry is there greater possibility of injury to CHEMICAL OPERATIONS others and destruction of property through the thoughtless act E. I. du Pont de Nemours & Company has chemical plants of a careless man. The first and indispensable step towards proper discipline is a careful investigation of every accident, manufacturing high explosives, smokeless powder, acids, charcoal, dyestuffs, certain cellulose products, and chemical labora- major or minor. We hesitate to use the expression “fixing the responsibility,” but the extent of the responsibility of the intories, etc. It also has what might be termed “nonchemical dividual, the foreman, the superintendent, and the management operations,” including plants manufacturing paints, other cellumust be determined, not on the basis of actual results, but upon lose products, blasting caps, boxes, shooks, etc., and also misthe basis of what might readily have happened. It is generally cellaneous construction work. (The manufacture of black powstated that 75 to 80 per cent of accidents are caused by the der, a mechanical operation with chemical hazards, is in an anomcarelessness or ignorance of the employee. This is open to alous class and has been excluded.) For the year 1922 the relaquestion. It is probably true that 75 to 80 per cent might have tive accident records of these two groups were as follows: been prevented by greater care or by display of greater intelliChemical h’onchemical gence on the part of the employee, but many might also have been Payroll force 3269 4700 Injury frequency rate 29 34 prevented by foresight and action on the part of the foreman, Lost time rate 0.52 1.09 the superintendent, or the management. I n fact, accidents for I n this comparison there is nothing to suggest the presence which the responsibility is single are the exception rather than of a preponderant chemical hazard, and on a well-established, the rule. Humanly, the blame is generally placed “on the well-ordered plant one generally finds that the process men as other fellow.” a group are as well able to maintain a long record without injury In this connection the following assignment of responsibility as the mechanical group. I n fact, the most frequent general cause for du Pont Company injuries in 1921 is of interest: of injury in any group is handling of objects such as boxes, ---On Basis of--barrels, or other containers by hand. Frequency Severity The foregoing relates to frequency of accidents and lost time “/o % Unavoidable: from accidents. Lost time, however, is not a true measure of Unknown physical deficiency 2.6 0.8 23.0 43.8 Risk of employment severity, but must be weighted for mutilations (permanent disTOTAL 25.6 44.6 ability cases) and death. If such basis of comparison is used Fault of employer: Defective construction or equipment 16.0 3.9 we find that chemical plants rate higher than nonchemical plants, Lack of proper safety appliances 4.8 19.1 Lack of proper supervision 10.9 10.4 owing t o the more frequent occurrence of serious injuries and TOTAL 31.7 33.4 fatalities in the former. The extreme condition is probably enFault of injured: Negligence or lack of skill 29.9 12.5 countered in explosive manufacture, where a relative trivial occurDisobedience 3.9 0.5 rence that would under ordinary conditions cause only a slight Failure t o use safety appliances 1.4 0.4 Failure t o report injury 3.4 8.0 injury, or even no injury a t all, leads to a n explosion and death. TOTAL 38.6 21.4
EFFECT O F EMERGENCY METHODS It has been pointed out that accident frequency is low in a wellestablished chemical plant. It is unfortunate, however, that
Fault of fellowemployee: Negligence or lack of skill Disobedience
TOTAI,
3.5 0.6
4.1 100.0
0.6 0.0
0.6
100.0
860 .
I-YD U S T R I A L A N D ENGINEERING C H E i I S T R Y
This tabulation is a frank statement of findings, and definitely contraverts the loose statement that the majority of injuries are caused by the negligence or ignorance of the man injured. One wonders what would be shown in a similar tabulation of the experience of a large corporation which had not consistently expended money and effort in accident prevention. Next in importance to proper discipline is the careful selection, assignment, and instruction of new employees. Du Pont Company experience shows that the accident-frequency rate for employees of less than one month’s service is twice that of employees of one year’s service or over. If there are special hazards from toxic materials, new employees should be physically examined, graded, and assigned only to employment to which they are suited. At the Dye Works, for example, accepted applicants are physically graded into three active classes and a fourth class to which employees are assigned for light work only. Employees of the first two classes are physically examined each month. The various operations are also graded into four corresponding classes. The first class involves exposure to nitro and
Vol. 1.5, No. 8
amido bodies; in the second class, these bodies are present but direct contact with them is unlikely; in the third class, such bodies are absent or contact with them is practically impossible; the fourth class covers miscellaneous light work. No employee of one class is permitted to work in a process of a more hazardous class, this restriction applying also to mechanical and labor department employees, who are graded in the same manner as the process workers. Much might be written of other essentials of a safe chemical plant, the least of which is by no means scrupulous cleanliness in mechanical, structural, and human equipment. The same outstanding deduction, however, is to be drawn in every case-that what reduces accidents makes also for increased efficiency. It is sometimes difficult to show in book values the profits that accrue from organized safety work, properly conceived and conscientiously carried out, because such profits, though real, are often intangible. On the other hand, no one will gainsay the economy of ‘‘efficiency,]’and if safety and efficiency go hand in hand, what greater encouragement to prevent accidents should we demand?
Recent Important Investigations in t h e Chemistry of Rubber, and Substantiation of t h e C5H, Ratio’ By Harry L. Fisher THB B. F. GOODRICH Co., AKRON,OHIO
A review has been given of the more important recent investigations on the chemistry of rubber showing the following results: ( I ) Substantiation of the CSHSratio and the C6H8 nucleus as the fundamental grouping in the rubber hydrocarbon, and the presence of a double bond for each c&8 nucleus. ( 2 ) Hydrogenation of rubber directly and in solution has been accomplished.
( 3 ) Studies in oxidation have produced new products, especially (CSHSO),. (4) Viscosity measurements have shown that the change during the heating of a solution of rubber is reversible, provided air is excluded. ( 5 ) Concentrated sulfuric acid on a rubber solution produces what appears to be an isomerized rubber.
N
the rubber all the time by keeping it in an atmosphere of carbon dioxide. The results of their analyses are so good and so important t h a t it seems worth while to give them here. Harries’ best result is also given for the sake of comparison.
OT since the publication of Harries’ work on the ozonides and hydrohalides of rubber a decade ago has so important
a paper on the chemistry of rubber come forth as that by Pummerer and Burkard.2 These chemists have accomplished the “impossible”-they have hydrogenated rubber a t ordinary temperatures. Furthermore, by extremely careful work they have substantiated by analysis t h a t the empirical formula of the rubber hydrocarbon is C6H8, and by their method of hydrogenation that each C5Hs nucleus does contain a “double” bond.
THE C6Hs RATIO It is interesting that their paper should come out a t the same time that serious questions were being raised concerning the empirical formula of rubber. Kirchhof3 has given much time in reviewing the work of many authors, including himself, in an effort to show that the empirical formula is ClOHl7 (instead of CloHl6, which is the same ratio as CbHs), and indeed the array of evidence is considerable. However, he presents the figures only and does not a t the same time compare the methods of preparation of the samples for analysis. Pummerer and Burkard were unusually careful in this regard. They recognized the ease of oxidation of pure rubber and how readily a small amount of oxidation which nil1 vitiate an analysis can occur. Therefore, although they used Harries’ procedure in general, they protected 1 Received February 23, 1923. Presented before t h e Division of Rubber Chemistry at the 65th Meeting of the American Chemical Society, New Haven, Conn , April 2 t o 7, 1923 2 Ber., 6 6 , 3458 (1922), C A , 17, 898 (1923). 3 Kollozdchem. Bezhefle, 16, 47 (1922); C. A , , 16, 4363 (1922).
-C-Pummerer and Burkard.. . . . . ,
. .
Harries‘
Calculated ,
. . .Found
. . . . , . . , . . , , , , Found
87.99 87.99 87.89
H -88.15 87.96
87.85
8:7;11.81
1
11.85 11.82 12.28
DOUBLEBONDSSHOWN BY ADDITIONOF HYDROGEN The other serious question settled by Pummerer and Burkard is the nature of the unsaturation. Recently, Boswell6 has proposed a new structural formula for rubber largely on the basis of its containing no double bonds. His argument is as follows: With double bonds existing in the rubber molecule, it should be possible to add hydrogen directly and produce a saturated hydrocarbon. The endeavors of Harries and of Hinrichsen and Kempf to accomplish this failed. Likewise, all attempts made in this laboratory were unsuccessful. This would seem to indicate that rubber contains no ethylene linkages a t all. Belief in the unsaturated character of rubber depends on the observations t h a t rubber adds on approximately four bromines and two hydrochloric acid mols for each CloHle. However, as these are admittedly very drastic actions, almost certainly accompanied by deep-seated depolymerization of the rubber molecule, it is conceivable that the rubber mol itself contains no double bonds PRESENCE OF
4 “Untersuchungen fiber die naturlichen und kunstlichen Kautschuk . arten,” p. 7. 6 Can. Chem. M e t . , 6, 237 (1922); India Rubber J., 64, 981 (1922).
