More on Chemical Stereoviews
To the Editor: Since writing the note on the construction of a resource file for chemical stereoviews,' I have come across a number of additional references dealing with the history of chemical stereoviews as well as several new sources of ~otentiallvuseful stereoviews, both of which may be of interest to the leaders of THIS JOURNAL. Dr. Ivan Bernal has called my attention to an extremely interesting collection of steteoscopic drawings, edited by von Laue and Mises, and published as two separate volumes by Springer Verlag in 1926 and 1936.2These volumes contain a total of 48 hand-drawn stereoviews illustratine the 14 Bravais lattices and the structures of 34 elementsand simple inorganic compounds, ranging from NaCl to perovskite. The 1921 crystallography text hy Groth3 also contains a collection of stereoviews, though these are stereophotomaphs . . of actual physical models rather than line drawings. OF The back cover of the April, 1929 issue of the JOURNAL CHEMICALEDUCATIONcarries an advertisement for Fisher Scientific, complete with a photograph, of a "Camerascope" for "visual instruction in X-ray crystallography." This device sold for the then rather expensive price of $18.00 and consisted of a small folding stereoscope and 37 ~tereoviews.~ From the description it is apparent that it was essentially an American version of the Braze set mentioned in mv .orieinal note. As for sources of stereoviews, the first volume of the series "Molecular Structures and Dimensions." nuhlished bv the International Union of Crystallography,s contains close tb 920 com~uter-drawnstereoviews of organic comoounds. oreanometallic P-complexes, charge-transfer compiexes, cl'athiates, carhoranes, and traditional metal complexes of organic ligands. Regrettably, a similar source of stereoviews for nonmolecular solids is apparently still lacking. uu
LETTERS
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William 6. Jensen
Universily of Wisconsin Madison, Wi 53706 The Error in in x
To the Editor:
' Jensen, W.B.. J. CHEM.EDUC.,59,385 (1982).
I found Leonard Nash's article on the "Ice Point and Tride Point" in the December 1981 issue quire interesting, pariiccan vield a ularlv his poinrinr out that a four dicit . logarithm . six &igit a&loga;ithm. Although his demonstration was most convincing, I should like to suggest an alternative derivation of his result. If we use the notation of calculus for finite changes (errors), then we may write than an error in x, d(x), causes, in the logarithm of x, In x, an error d(ln x) given by
von Laue. M., and Mises, R. (Editors),"Stereoscopic Drawings of Crystal Structures," Vols. 1 and 2, Springer, Berlin, 1926 and 1936. Groth. P., "Elemente der Physikalischen und Chemischen Kristallographie," Oldenbourg, Berlin, 1921. J. CHEM.EDUC., 6, 4 (1929). Kennard, 0.. et al. (Editors), "Molecular Structures and Dimensions," Vol. A l , International Union of Crystallography, 1972.
The Supporting, Rather than Initiating, Role of Science In Technology
Thus d(x) = x d(ln x), the error in x is x itself multiplied by the error in the logarithm. = In one of Nasb's cases, where in x = -8.230 X -0.0008230, if we assume an error of +l in the last digit quoted, then d(ln x) = 2 X 10-7. Now x itself is manifestly near 1(i.e., 0.9991. ..),thus
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or the resultine x is determined to within 2 in the seventh figure. Note that the above relationshio indicates that the error increases with increasing x and that the inverse process of obtaining In x, given x, can lead to quite large errors if x is very small. Oliver G. Ludwlg
Villanova Universiw Villanova, PA 19085
TO the Editor: In his editorial in the May, 1982 issue of T H I S JOURNAL ("The Public Attitude Toward Science"), J. J. Lagowski correctly laments the priorities of the American public for the support of science and technology with tax revenues, as indicated by the most recent annual report of the National Science Board. Science Indicators 1980.He comments that "It should be more than slightly disturbing to the scientific communitv that the eeneral Dublic ~erceivesthe acauisition of new knowledge-;he fundamenial basis of modern technoloev-to be so lackine in merit as to lace it amone the lowe% on the list of areasto be supported." While the pub~ic's lack of appreciation for the benefits to modern societv of fundame& research is indeed cause for concern, ~ a ~ o w s k i ' s justification for the acquisition of new knowledge as "the fundamental basis of modern technology" is ill-suited to his purpose. Historians of science and technology have in recent years devoted much effort towardsthe elucidation of the inVolume 61
Number 3 March 1984
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teraction between science and technology, and a consensus has emerged that technological innovation most often evolves from prior technology, and that when pure science does play a role, its relation to the technological develo~mentsare seldom those of cause and effect. In a-careful study, for example, British technolo~icalinnovations of 196fiIfi7. of 84 s~~ccessful F. R. Jevons found the role of science to he a supporting, rather than an initiating, one and that in no single case was an innovation induced by a scientific discovery.' If we choose, as many of us do, to justify the pursuit of knowledge primarily by consequent tectkolo&al innovations, then the importanceof pure research will he diminished if,as seems likelv. .. the "iustifi(:ation is rendered iwalid. It is importaut for modern scientists, of whom chemists form a large percentage, to seek societal support for the pursuit of new knowledge as an integral part of the cultural attainments of mankind, a part moreover which encourages us to appreciate, utilize, and live in harmony with, the world around us. Melvyn C. Usselman Univelrsity of Western Ontario London, Ontario CanadaN6A587 Jevons, F. R., Technology 8 Culhxe, 17,729 (1976). Liability Insurance To the Editor: A contribution to the Safety Column last November by N. T. and Marilyn C. Kurnathl has pointed out the increasing numbers of law suits charging negligence on the part of laboratory teachers. This has raised questions about liability insurance for the financial protection of teachers and prompts us to call special attention to the ACS Professional Liability Insurance Plan, just in case our readers failed to note the paid advertisement on page A344 of that same issue. Reductions in rates have made this coverage a genuine hareain in the o ~ i n i o nof vour Column Editor. For Deace of minh and the protection-of your solvency we recommend writinz for full information. Address inauiries to the American Profesiionnl Agency, Inc., 95 Broadway, Amitpille, NY 11701. Whe plan also ~ncludrsroveraee for industrial chemists. and an alternative plan is available for consultants.) Malcolm M. Renfew University of Idaho
Soiled Chemistry To the Editor: There are significant agronomic errors in the experiment entitled, "Soil Analysis for High School Chemistry Students," by Mary A. Eisenmanu, published in J. CHEM. EDUC.,57,897 (1980). The Discussion section has several significant errors: 1) The fertilizer analysis 15-5-10 means 15%N, 5% P2Ob and 10% K20, not 5% P and 10% K as stated in the article. The state fertilizer registration laws are 20-30 years behind the times. 2) In soil that is too alkaline (basic) (pH 2 8), the micronutrients zinc. comer. iron. and manganese are tied uo as insoluble phosphates'and the'phospha& ions (~1'0,2-)'are unavailable because of the formation of insoluble calcium and magnesium phosphates. 3) In acidic soils (pH 5 5) the micronutrients (trace elements) maneanese and iron become too available and may reach toxic levels. Aluminum becomes a significant ~ r o b l e malso. The ideal soil DH is 6.5. the DH of maximum major and secondary nutrient availabilit; and proper micronutrient availability. A professional soil testing laboratory tests for the primary and secondary plant nutrients-N as Nos- by specific ion electrode, P calorimetrically as the blue phosphomolyhdate complex, and K, Ca, and Mg hy atomic absorption-emission spectroscopy. The micronutrients are also determined by AA. A soil lah does not test for HC03-. pH is measured with a pH meter. Na-Churs Plant Food Company analyzes approximately 130,000 soil sample a year for its fertilizer customers. I will he happy to answer any questions about soil testing, agronomic recommendations, fertilizer manufacture, etc. Walter C. Crouse Direclw, Roduct Research NaChurs Plant Food Company 421 Leader St. Marion, OH 43302
An Alternative Proof To The Editor: Carl W. David's article, "Why is an LCAO-MO Not Necessarily an Eigenfunction," which appeared in the April 1982 JOURNAL provided one demonstration that &id = Is. 1 s b is not an eigenfunction of the one-electron Hamiltonian H. I would like to suggest a much simpler and perhaps more interesting proof. Consider
+
MOSCOW. ID 83843
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Kurnath, N. T. and Kurnath, Marilyn C., J. CHEM.EDUC., 58, A329 (1981).
But Is, is an eigenfunction of the first two t e r n in H, and isb is an eigenfunction of the first plus the last term in H. In each case, the eigenvalue is simply the hydrogen-like atom ground state energy EHL= -(13.6 eV)Z2.Therefore Hls.
Crlb Cards for Tests To the Editor:
- Ze21rb)t.
= (EHL
Hlsb = (EHL- Ze2/?'a)lsb and
I would like to note that Whitmer's suggested use of a 3 X 5 "crib card" on tests [J.CHEM.EDUC.,60,85 (1983)l is not limited to physical chemistry. I have successfully used the same idea for several years in my sophomore organic chemistry course and I concur with Whitmer's comment that preparing the card is an excellent focus for study. I have had students complain that by the time they have figured out what they are going - - t o ~ uont the card thev no loneer need the card. I recommend-iw use by instructok intere&d in testing the use of facts without te~tingthe memorization of those facts.
It is impossible to factor the last two terms to yield simply +*id multiplied by a constant. Therefore, is not an eigenfunction of H. This proof exploits essential properties of the Hamiltonian H as well as of the AO's Is, and lsb, and offsets any need to consider specific functional details.
John Henderson Jackson Community College Jackson. MI 49201
Frank 0. Ellison University of Pithburgh Pinsburgh. PA 15260
266
Journal of Chemical Education
H&i* = E H L ( ~+s1sb) ~ - (Ze2/rd1s, - (Ze2/r.)lsb
