To the Editor: I do not believe that qualitative analysis should be integrated with general chemistry (as discussed at the Atlantic City A. C. S. meeting and reported in Chemical and Engineering News, 34, 4791 (1956)). In "Qual" the fledgling chemist learns to correlate his knowledge of general chemistry. Two personal experiences can serve as arguments for this point of view. During the years when I was a laboratory chemist, I was occasionally reprimanded for having "changed the method." One such accuser was unaware of the chemistry underlying the specified procedure for To the Editor: determining mercaptan sulfur in a fuel. It involved The recent articles by K. J. Mysels (THIS JOURNAL a corrective back-titration with silver nitrate of the 33, 178 (1956) and E. A. Guggenheim (Ibid., 33, 544 erroneous (but anticipated) over-back-titration with (1956)) prompt me to write that the textbook, "Genpotassium thiocyanate. The other experience iueral College Chemistry," by F. Brescia (1) very defivolves the ludicrous interpretation given the instrucnitely separates the subject of reaction rates from tions by a technician. They were to "boil 2 5 3 0 chemical equilibrium; (2) uses kinetic data for the seconds to expel SO2 from an acid solution." The. reaction 2NpOs 4N02 + 0 2 to show the rate is proboiling time was regulated with a stop-watch! portional to the concentration of N,05 raised to the No, qualitative analysis should not be relegated to a jkst power; (3) states ". . . these concentration exminor role. It should be supplemented by courses in ponents cannot be predicted from the overall chemical quantitative analysis and an optional course in techequation; they are determined from an experimental nical analysis. study of the reaction rate"; (4) does not derive the quantitative expression for the equilibrium constant from rate equations.
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To the Editor:
To the Editor: I wish to bring to your notice the indiscriminate use to which silica crucibles are put in various gravimetric experiments. Previously porcelain crucibles were used in our laboratory (intermediate laboratory) for the determination of equivalent weight of magnesium by direct oxidation, for the determination of percentage loss on heating the given substance, etc. But this year we ordered four silica crucibles and got them in July, 1956. The silica crucibles were used last week for the determination of the equivalent weight of magnesium. After the experiment was over the attendant poured out the magnesium oxide. I n order to clean the adhering ash he added HCl to the crucibles. At once a slight crackling noise along with the evolution of a spontaneously inflammable gas took place. So it is evident that magnesium reacted with SiOz t o form magnesium silicide. When this was treated with (dilute) HC1 it yielded a mixture of spontaneously inflammable silicon hydride: Mg2Si 4HC1 = 2MgCIz SiHa. It burnt with a luminous flame. So I wish to bring t o the notice of chemistry lecturers through your Journal that silicon crucibles should not be used with magnesium or calcium as some of the metal reacts with the silicon to form the silicide.
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K. R. KRISHNASASTRY G. A. COLLEGE CUDDAPAH, ANDHRASTATE,I N D I A VOLUME 34, NO. 3, MARCH, 1957
I have just read the "Editor's Outlook" in the November issue of the JOURNAL OF CHEMICAL EDUCATION and agree with much you have said. Not all the good training, however, is provided by small liberal arts colleges, nor are all the large state schools and their chemistry departments neglecting these responsibilities. The Department of Chemistry of the University of Texas is active in two areas of teacher education-the training of teachers through revised and modernized degree programs in the College of Arts and Sciences and through an active summer program for high-school teachers. A recently enacted state law of Texas makes teacher certification the responsibility of the whole university. This certification is based on approved degree programs. The College of Arts and Sciences, through its Committee on Relations with Public Schools, has taken this opportunity to develop course programs which permit the student to receive a B.A. degree from the college and also teacher certification. The students receive the liberal education of our B.A. degree, the pedogogy of the College of Education, and subject matter training from specialists in specific fields of interest. At present the various degree programs within the College of Arts and Sciences are based on existing courses. We are now actively exploring the possibility of new courses being designed specifically for the secondary school teacher, taught by Arts and Science faculty, but having a listing in the College of Education as well. This will help relieve the burden of 24 hours required in Education courses. We also plan to assist in practice teaching.
