Harold F. Walton University of Colorado
Boulder, 80302
The Most Enioyable Course I Ever Taught
Comparisons are odious, and enjoyment cannot be quantified. It is enough to say that the course in instrumental analysis that I taught in June, 1970, in Caracas, Venezuela, was one of the most exciting I have ever taught, and it set me wondering why my regular courses a t the University of Colorado seem to fall so flat. I could do better in my regular courses if I tried. Perhaps other readers of the JOURNAL OF CHEMICAL EDUCATION could make the same confession. The glamour of a, foreign country and another language helped, naturally, but would not justify writing an article about it. If I need an excuse, let it be that our course was sponsored by USAID, and taxpayers have a right to know where their money goes. The course was actually a continuation of another short course taught in 1969 by Professor Jerry M. Fitzgerald, of the University of Houston, and myself. It was cqntinued by popular request, and I had essentially the same group of students that Jerry and I had in 1969. There were about twenty teachers of chemistry, biology, pharmacy, and geology from universities and high schools. Our host institution was the Pedagogical Institute o f Caracas. This should not be confused with the Central University of Venezuela, which is also in Caracas. The Central University has a large and beautiful campus, plenty of money, and good equipment, yet scientifically speaking it is almost a nonentity. The reason: politics. The tragedy of higher education in South America is that many universities with distinguished histories have been wrecked by strikes and political strife, and I've seen enough,to make me sensitive about such matters in the United States. The Pedagogical Institute is small and relatively new, and fairly free, so far, from disruptive politics. It is handicapped by lack of funds and building space, but our laboratory had a few nice instmments, thanks largely to the Creole Foundation. The course was built around these instruments. They were Ultraviolet-visible spectmphatometer, Zeiss PMQ-11. This is a precision instrumeht with quartz prism, single-beam, no recording, going up to 2.5 p in the near infrared Bausch and Lomb Spectronic-20 spectrophotameter Infrared spectrophotometer, Perkin-Elmer 700 Gas chromatograph, Perkin-Elmer F-11, double columns with flame ioninalion detecton; no temperature programming pH meters, Beekman Zeromatitie and Radiometer Equipment far thin-layer and paper chromatography
My "boss" and the guiding spirit in the course was Dona Olga Martin de Larralde. She is a senior member of the Institute faculty and one of the distinguished figures in Venezuelan higher education. While we were there she was decorated by President Caldera on the occasion of an anniversary of free public education
in Venezuela. Her husband is a retired physician. She combines tremendous energy with a delicious sense of humor, and it was her efforts, more than anything else, that got the course going. If I wanted anything I only had to mention it to Dona Olga and lo, next morning it was there. We also had the strong support of the Head of the Department of Chemistry and Biology, Professor Dimas Hernandez, and the Institute's director, Dr. Pedro Felipe Ledezma. At the beginning we decided how t o run the course. We would start each day with a lecture but spend the rest of the day in the laboratory. A schedule was arranged so that no more than six students would be in the laboratory a t one time. There would be no exams, but grades of a sort based on lab reports and homework. The laboratory would start with everybody doing standard experiments and following written directions, but as soon as possible we would pass t o individual projects of investigation. I suggested projects of two kinds, one of the "pure science" or physical chemistry kind, the pther the analysis of commercial products and natural materials. Students were free t o propose projects of their own, and did so. We started with an introduction to the chemical literature. The Institute library is pitiful, but 15 km from Caracas is the Venezuelan Institute for Scientific Research (IVIC), which has one of the best scientific libraries in Latin America. pJe drove there and looked at Chemical Abstracts, bound journals, and the imposing shelves of current periodicals. Thereafter my average day went like this. Lecture, 8 t o about 9: 15 a.m.,followed by a coffee break. Then to the laboratory until 6 or 7 p.m., sometimes later. There I was kept on the rup the whole time. My desk was ip a corner of the laboratory and if I tried to sit down for five minutes, someone came running to ask, !'How do we do this? How much water shall I add? The recorder isn't working? We have finished this experiment; now what do we do?" When they finally let me go my working day was not over. I had lab reports to read, or notes to typein my bastard Spanish to accompany the lectures or lab, notes to be Xeroxed and distributed next day, If I did not finish that night, I got up next day before breakfast. The students worked'cpite as hard as I did. Most of them were carrying a full teaching schedule, and some taught in two different places, braving the crowded freeways between times. If I can generalize from a small sample, the Venezuelans are tremendous workers. One senses this from the bustle of Caracas, which looks at first sight like Los Angeles without the smog, and has more tall buildings per square kilometer than any other city I've seen, New York included. Volume 48, Number 7, July 1971
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Four weeks of this pace was all I could stand. But there are advantages in an intensive course. If something came up in the lab that was of general interest, I talked about it in class next morning, and points that arose in lecture or homework could be illustrated in the lab without delay. Above all, I got to know the students. At the University of Colorado we have talked about arranging classes so that a student would take just one course at a time, or two, but we shied away from this proposal in the Chemistry Department because of the difficulty of scheduling the laboratories. It now seems to me that laboratory courses are precisely the ones that should be taught on an intensive full-time basis. Or half-time, anyway. It is easier to teach well when one is away from home for the very good reason that one has no institutional responsibilities, no committees, and no telephone. One is free to devote one's whole time and attention to teaching. Perhaps, with will-power and the sense to say "No," I could do the same thing at home. On the other hand, our students in the United States may not need such close attention. My students in Caracas did. Even though they were mature and motivated, their basic chemistry was weak, and they were not used to handling materials and equipment and "thinking with their fingers." They were used to cut-and-dried cookbook directions, and if something happened in the laboratory that was not mentioned in the cookbook, they did not know what to do. They had little conception of experimental errors and the checking of measurements. They would measure with great care 50 ml of water to dissolve a weighed portion of sodium carbonate for titration with acid, then try to weigh 5 mg of copper sulfate for a photometric standard on an old balance without checking the zero. They would take an absorbance reading of 1.85 from the spectrophotometer and, when this remained constant over a range of wavelengths, solemnly plot a level plateau on an absorbance-wavelength curve without checking the dark-current zero or worrying about stray light. They had to be led by the hand in the simplest experimental matters. But they learned, and they learned fast. And they really rose to the occasion in their independent projects. The most spectacular project was carried out by two girls who taught biology. They had been breeding fruit flies and wanted t o examine the visual pigments by paper chromatography, following an article they had read in the Scientific American. They brought jars full of Drosophila to our laboratory and asphyxiated the flies, then cut off their heads under a dissecting microscope, and mashed their heads with a glass rod into the starting line of a sheet of chromatographic paper. The spots of mashed-up flies' heads were run in the dark with an appropriate solvent mixture, and the paper was examined by ultraviolet light. Some spots could be seen without ultraviolet; others fluoresced, and one that was invisible by ordinary light gave a brilliant blue fluorescence. The genetic differences were very striking to a layman like me. Needless to say, there were many jokes about beautiful senoritas who ground out the eyes of their victims. Most of the projects related t o commercial products. One man went all over Caracas collecting samples of plastic film and running their infrared spectra, identi462
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fying their constituents and estimating their thickness from the interference waves. Another ran gas chromatograms on three grades of gasoline and showed that the higher the price, the higher the proportion of volatile hydrocarbons. And we discovered how badly one needs temperature programming for a job like this. On the gas chromatograph we identified and measured the three peaks of commercial xylene, ran mixtures of benzene, toluene, and xylene a t various temperatures and compared column packings. Everybody enjoyed working with the gas chromatograph. We found the flame ionization detectors t o be extremely reliable and ideal in a country where helium is hard to get. The insensitivity of this detector to water was illustrated by my special project, which was an examination of the local aguardiente. Disappointingly, I only found one big peak for ethyl alcohol. I wished I had some of the stuff I once tasted on the banks of the Huallaga River in the jungles of Peru. As it was, we contented ourourselves with measuring the alcohol concentration using methyl ethyl ketone as internal standard, and noting that the peak height served quite well, as it should, as a measure of concentration if the sample was small and the right stationary phase was used. I produced a bottle of aguardiente from under the lecture table one morning and observed that it contained enough for 750,000 one-microliter samples. The chlorophylls of spinach were examined by column chromatography, and one man, who worked part-time in a laboratory for agricultural products, was examining vegetable oils by infrared. A geologist determined the copper in soils by diethyldithiocarbamate, and got experience in trace analysis, reagent blanks, and quantitative dilutions. (It is so easy to lose factors of ten in quantitative dilutions. This happens at home too!) We measured the phosphate in baking powder by potentiometric titration after conversion to phosphoric acid by cation exchange. We titrated detergents and found them to contain other basic anions besides phosphate. We wanted some dry sodium carbonate to standardize our acid, and finding an opened bottle of partly hydrated sodium carbonate we dried the salt by heating in a large test tube, then found on titration that we had decomposed a little of it t o sodium oxide. We then went t o the thermodynamic tables and found that sodium peroxide, not monoxide, is the stable product when sodium carbonate is heated in the presence of air. All these findings were duly entered in the students' reports. Potentiometric titration fascinated the students, especially when done with our beautiful new Radiometer pH meter. We scrounged a silver electrode from IVIC and used it t o titrate the chloride formed by combustions in a Schoniger oxygen flask, made for the occasion by a glassblower at the Pedagogical Institute. The oxygen flask was the special baby of a man whom I shall call the Michael Faraday of the Pedagogical Institute. He was employed as a lab boy and bottle washer, and I had known him in that capacity in 1969. This time he not only kept the lab in order but took the course as well. Because he knew his way around a laboratory, he needed only minimum direction. He rigged up electrodes for dead-stop titrations, did iodine-arsenite and aniline-nitrite titrations, and when
I mentioned the Karl Fischer reagent, Dona Olga had a bottle of this reagent on the desk next morning and Michael Faraday used this too. Later he and another man started to compare two methods of determining water, Karl Fischer and the absorption a t 1.89 p, but this project was never finished. We ran many ultraviolet spectra by point-by-point plotting and devoted special attention to caffeine. We determined caffeine in headache tablets after separating it by solvent extraction in the official way, then we worked out a method for separating caffeine by absorption from acid solution on a cation-exchange resin, later desorhing it and measuring its concentration by ultraviolet. The method worked beautifully for caffeine-aspirin tablets, and I hoped to develop it to a point that would warrant a note in THIS JOURNAL, but time ran out on us. The most "intellectual" project was the measurement of formation constants of metal complexes of salicylic acid by the Calvin-Bjerrum titration and by spectrophotometry. This was the work of Profesor Cecilia de Hernhdez, who also helped run the course. She teaches analytical chemistry a t the Imtitute, has four children and a husband, Dr. Aditn Hernsndez, who teaches organic chemistry. Both have studied in the U.S. They work ten hours a day and live a t the other end of Caracas, and illustrate what I mean about hard work, energy, and drive. The last three class sessions were devoted to reports by the students on their research projects. These
were most impressive. It was obvious that these people are professional teachers who take pride in clear exposition. Summing up the value of the course, a general comment was "We have lost our fear of instruments." Usually Saturday was a holiday, hut we worked our last Saturday morning and had a brief closing ceremony. Then being South Americans, the group took my wife and me to a grand almuerzo de despedida. I can't translate this. The words "farewell lunch" are flat and inadequate to describe the feast a t one of the best restaurants in Caracas, "El Alamo." Nor can I translate the word carilio, but everybody who has lived in Latin America will know what I mean. I hope I have persuaded my fellow-taxpayers that the AID dollars that paid my plane fare and per diem were well spent. Nearly all my salary was paid by the Pedagogical Institute with funds from the Creole Foundation. In 1969 it was the Venezuelan government that paid the salaries of Dr. Fitzgerald and myself. I have seen the balance sheets for the AID educational program in Venezuela; in 1968-69 the U.S. paid 23% of the costs, Venezuela 77%. I'm prejudiced, but as a taxpayer I am proud to contribute my few cents a year to programs like this. Finally I acknowledge the enthusiastic support of the U.S. Embassy staffin Caracas, especially Mr. Eldon Stewart, Head of the Human Resources Division of USAID, and Dr. Alan Braswell, who was the liaison with the Pedagogical Institute.
Volume 48, Number 7, July 1971
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