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INDUSTRIAL A N D ENGINEERING CHEMISTRY
question is false. There is no doubt that any profits which industry got in the last twenty-five or thirty years were derived only from the knowledge and hard work of the chemists, and that the latter only developed those principles which were given to them by the chemical schools, no matter how high or low these schools stood in matters of teaching. The ohief trouble lies in a quite different direction. It is the chemist who has been too much and too long handicapped by the unfitness of his education. It is he who can never say beforehand in which line of industry he will fit inLthe future and who never can be sure that his innate abilities for doing this or that kind of work will find suitable application. The proposed changes will help right many unpleasant situations of the present time, and in these particular ways; (1) The old degrees of bachelor, master, and doctor will cease to exist. At present they help only to mix all chemists to a quite indefinite mass. (2) The same will happen to the indefinite terms of “chemist” and “chemical engineer.” They will be changed and become imbued with a far more real meaning. (3) A quite different type of spirit will find its logical expression and as such lead to the formation of chemical social bodies having identical interests and the same social standing. Societies of analytical chemists, of research chemists, of chemical engineers, etc., can develop strong social wills, and become quite able to insure for their members proper conditions of work and remuneration.
Vol. 15, No. 2
(4) Employers will know exactly where to find the special type of chemist suited for particular needs. They will not ask a man with engineering abilities to become an analytical chemist, and the analytical chemist will not have the temptation to go in the construction bureau or to become a salesman. RESEARCH CHEMISTS AND CHEMICAL ENGINEERS
No matter how great the changes may be that are contemplated in the system of chemical education, there will always remain two groups of chemical workers who cannot under the present system be guaranteed against unemployment in times of financial stress. These groups will include those most valuable from the standpoint of humanity and the nation, the research workers and the chemical engineers. The suggestion that employers make special provisions to hold these men through times of depression is naive in the extreme and certainly has been made without consideration of present-day economic trends. Luckily enough these two groups are small and this makes the problem of their 1i;Ving less difficult. It is proposed that these two groups be considered from the time they enter training as a specialized corps working for the nation. Just in the same way as the nation supports the army and navy, it should support these, men for the benefit of industry. Arrangements should be made that they be available to industry in case of need, but that during times of financial depression they may be considered as governmental employees . and allowed to continue their work on problems of universal application.
The Importance of “Impurities”’ By Jerome Alexander 50
EAST41sT ST.,N E W
ONTINUALLY throughout human experience principles of great importance have lain unrevealed, because no one understood or even noticed some minute or seemingly unimportant impurity which was the key to the correct understanding of the situation and would have opened the door to a big advance in knowledge. The recent recognition of vitamins has rendered necessary a complete revision of our data on food values, but there is no reason why they could not have been discovered long ago, had some one only investigated, for example, just why cod-liver oil is valued so highly. The early British explorer Captain Speke reported a then curious superstition among the Congo natives, that the coming of the tsetse fly was associated with the incidence of sleeping sickness, but scientific men took no notice of a “native supersiition.” Now, however, we appreciate the role of the insect carriers of disease-the mosquito for malaria and yellow fever, the wood tick for Rocky Mountain or spotted fever, the rat flea for bubonic plague, etc. Other biological instances of the devious ways of nature are found in the fungus that causes the rust in wheat, which must spend part of its life in the barberry; in the fresh-water mussel which spends part of its life in the gills of certain fish; and in the curious life cycles of the trichina and the tapeworm.
C
IMPORTANCE OF
MINUTEQUANTITIES OF
“IMPURITIES”
I n considering the question of impurities from the standpoint of the chemical engineer, we must in the first place stress the point that excessively minute quantities of substances may exert I Presented before the 15th Annual Meeting of the American Institute of Chemical Engineers, at Richmond, Va., December 6 to 9,1922.
YORK,
N. Y.
effects of technical importance. Bredig reports that one part of platinum black will decompose one million parts of hydrogen peroxide, the manufacturers of which well know the stabilizing action of such substances as acetanilide commonly used in the commercial product. According to Brodie, one mol of molybdic acid in 33 million will exert an appreciable influence upon the reaction between hydrogen peroxide and hydriodic acid. The great power of the enzymes is well known-one part of invertase will hydrolyze 200,000 parts of sucrose, and one part of rennet will clot 400,000 parts of caseinogen-although enzymes are never of 100 per cent purity. In fact, their very impurities stabilize them. According to E. F. Armstrong, lactase may effect in one hour a change that would take 2 N HC1 a t 35” C. three weeks to accomplish. Another point to remember is that minute traces may produce results quite contrary to those produced by larger amounts. This is commonly the case with antiseptics and has been illustrated with experiments on €ertilizers containing borax. Biological reactions are especially delicate-witness the tremendous power of the bacterial toxins. According to Bertrand, one part of manganese in 10 million exercises a visibly beneficial effect on the growth of Aspergillus niger, although Raulins found that one part of silver nitrate in 1,600,000 parts stopped its growth, and an attempt to raise the fungus in a silver cup proved futile. Duclaux, commenting on this, remarked that “it is almost impossible to detect chemically any dissolution of silver into the liquid. But the fungus proves it by dying.” In view of these facts we can understand the predilection of the oid-fashioned housewife for copper or brass preserving kettles, especially as
I N D UETRIAL A N D ENGINEERING CHEMISTRY
February, 1925
we now know the fungicidal and chromostatic action of traces of copper; also the value of baked potatoes, which retain all their soluble salts. Surprising results sometimes follow the presence or absence of traces. Prof. H. B. Baker2 reports enormous increases in the boiling point of liquids that had been superdried by standing some years in the presence of phosphorus pentoxide. His results showed:
..................... ................... ..................... .....................
Bromine Mercurv.. Hexane. Benzol.. Carbon disulfide. :. Carbon tetrachloride. Ethyl ether.. Ethyl alcohol.. Methyl alcohol. Propyl alcohol..
............ ......... ................ ......... ......... .........
Years Standing 8 9
Increase in Boiling Point 550
62
8 ‘/P 81/2
1 9 9 9 9 9
Absolutely pure zinc sulfide does not give luminous paint, though it is not easy to determine the activating impurities. Iodoform owes its antiseptic value to the iodine it splits off, and if catalytic impurities are absent it may fail to work-too pure a drug is valueless. Minute amounts of iodine are essential in food if goiter is to be avoided. A continually renewed supply comes into the atmosphere from colloidal sea salt resulting from the ocean’s spray. VALUE O F DETECTION Impurities may be telltales. Thus the Germans, on analyzing the British “mustard gas” (diethyldichlorsuliide), learned from the impurities present just how it was made, and scrapped their inefficient method for that of Sir William Pope. Extreme care is necessary in detecting impurities. The rare gases of the atmosphere had been isolated by Cavendish, and W. F. Hillebrand had isolated helium from cleavite; but Sir William Ramsay’s genius for taking infinite pains, revealed argon, helium, neon, xenon, krypton, and niton. HELPFUL AND TROUBLESOME TRACES
Traces of substances may be beneficial or detrimental, and a few instances thus classified are as follows: HELPFUL%uces-The resistance of the tungsten filament, according to W. C. Whitney, is increased by traces of rare metal oxides where larger quantities have failed. The value of traces of salts in water for brewing, baking, and other operations is beginning to be appreciated, and we hear now of these being added as “yeast foods” and in “Burtonizing” water. Sodium bromate is said to have reduced the yeast bill of one large baking company from $1,000,000 per year to $500,000 per year. While 0.216 per cent of arsenic reduces the conductivity of copper 39 per cent, pure copper rolls much less readily than that containing arsenic, and yields tubes that corrode ten times more rapidly. A little lead in brass makes it machine easily and prevents chattering. The reputation of Swedish iron is due to the impurities, mainly manganese, it contains. A little copper inhibits the corrosion of steel. Small quantities of barium (0.07 per cent) harden lead and make it ring like a bell. In many alloys small quantities of aluminium deoxidize the melt and prevent atmospheric corrosion of the casting. In the electrodeposition of metals, small quantities of “addition compounds,” which are in many cases protective colloids, give a desirable cathodic deposit. The experience of Auer von Welsbach, who found the great effect produced by ceria in the thoria mantle-the optimum value being about 1 per cent-is well known. Thus, in a certain flame a pure thoria mantle gives 7 c. p., whereas the standard mantle with 1 per cent ceria gives 88 c. p. With 0.25 per cent ceria the luminosity sinks to 56 c. p., while with 5 per cent ceria it is only 44 c. p. Goodyear had no trouble in vulcanizing his rubber, because of the various nitrogenous impurities present in the crude product
* Trans. Chrm. Sac.,
2 1 (1868).
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of his day. With the advent of modern pure plantation rubber it has become necessary to add various accelerators. Old patents show that celluloid dissolved in the “wood spirits” of that day, which contained ketones in considerable quantity, but refined methanol is not a solvent for it. Traces of lead tetraethyl will take the “gasoline knock” out of an internal-combustion engine, even 0.06 per cent being effective. TROUBLESOME TRACES-The mercaptan intermediate in making sulfonal has an appalling odor, and as one four-millionth of a milligram is readily detected, it presents a technical problem quite on a par with “poison gas.” In hydrogenation the catalyst is readily poisoned. Sabatier reported that traces of bromine in the air of the laboratory made it impossible to hydrogenate phenol that had stood there in an open flask; and thiophen prevents the hydrogenation of benzol to cyclohexane. This recalls Victor Meyer’s experience. While attempting to exhibit to his class his color reaction for benzol, he happened to use an especially pure benzol and the reaction failed to materialize. The failure led to the discovery of thiophen as the unsuspected impurity that had been responsible for the reaction. When mechanical presses were used to squeeze out the grape juice for sherry wine, instead of the old method of “treading the wine press” with the bare feet, the wine did not have the right flavor. The more efficient machine introduced some of the bitter substances next to the seeds. I n making dry batteries, traces of h-on in the pyrolusite, or of copper in the ammonium chloride, are highly objectionable. One part of sulfur per million of coconut oil is said to create trouble in the soap-making process. I n lead burning, traces of arsenic ip the hydrogen used to make it impossible to secure a good joint. Attempts to make a good nickel steel were for years frustrated by impurities present in the commercial nickel of the day. A manufacturer of brewing sugar came to see how his new product was working in a brewery and found the brew-master running an inky black liquid into the sewer. Being a chemist, the manufacturer immediately wired his analytical department that its product was full of iron, and in reply received a telegram saying that the batch complained of had only 0.002 per cent of iron. But that was enough to make plenty of ink with the hop tannins. Even 0.1 per cent of pyridine in ammonium nitrate used for filling shells in 80:20 admixture with trinitrotoluene, produced enough gas to cause “spewing.” The contact mass used in making synthetic ammonia is very sensitive; sulfur dioxide poisons it, as do selenium, tellurium, phosphorus arsenic, boron, and to a lesser extent lead, bismuth, and tin. Iron containing even as little as 0.01 per cent of sulfur is quite useless for making the contact body. White leather cannot be produced in the presence of traces of iron or copper. Color lakes or dyeings are thrown off shade by traces of iron, but here one may make a virtue of necessity and produce a new shade by liberal use of the impurity. Bismuth, cadmium, and antimony injuriously affect brass. Sulfates interfere with the electrolysis of magnesium chloride and the electrolyte production of sulfates. Iron, cobalt, and especially antimony seriously affect the electrolytic deposition of zinc. In determining hydrogen-ion concentration traces, of impurities may poison the platinum electrode and give incorrect results. Very pure hydrogen sulfide, carbon disulfide, and phenol are practically without odor. Tellurium is d3icult to handle because traces are absorbed and gradually eliminated, giving the worker a frightfully unpleasant aroma. Instances of character similar to those given are undoubtedly familiar to all. It is essential, however, to bear in mind continually the fact that so-called negligible traces may make or mar a pr.ocess or a product.
