Problems with Using CAS ONLINE: Why Can't Abstractors Spell? To the Editor:
CAS ONLINE, the computer version of Chemical Abstracts, is a valuable asset to the chemical profession (1-3). The first of a series of papers introducing students to online searching of this data base has already appeared in this Journal (4). Yet CAS ONLINE does have shortcomings, knowledge of which may help increase the efficiency of a search. Occasionallv. .. a search term, which I had accidentally misspelled, would return a nonempty answer set. A systematic exoloration of this oddity has revealed extensive misspelling of terms in the ~asic-Indexthat frequently makes the record inaccessible through the intended term. The resultsgiven here were obtained on January 7,1987; the specific words are related to this author's own research interests. A common error is to droo the second "I" in the name of the drug, pn,pranolol, to give the misspelling "propanolol". 16.12citarions were retrieved when the Rnsir Index uf the CA File (4) was searched with the correct spelling, and 312 (nearlv 7% of the total citations) were returned with the incorrect spelling. Of the latter, 75 (nearly 2% of the total citations) could be accessed only with the incorrect spelling. Ironically, a significant number of these records had propranolol spelled correctly in the abstract, which is not searched, but not in the Title, Keywords, or Index Terms, which are searched (4). Of these, 26 (35% of the solely misspelled sample) could not be accessed through the Registry Numbers for unspecified, D-, L-,and DL-propranolol. (In some cases this reflected discussion in the papers of a salt, complex, derivative, or analog of propranolol, but in others the Registry Number is simply missing from the Index Terms. Occasionally, the Registry Number is given in the abstract itself, hut not in the searchable items.) The last set never would be retrieved by a searcher who did everything properly. Erythrocyte is frequently misspelled "erthrocyte" (first "y" dropped). Here 34776 citations were returned with the correct spelling and 123 (0.4%of the total) with the misspelling. Six (0.02%) could be accessed only with the misspelling. Even common words are beine entered incorrectlv into the CAS data base. Misspelling human as "humamnreturned four citations. Of these.. one.. a vaoer on alloimmunization in the human, could be recovered only with the misspelling. Based on this exploration, I offer two recommendations. (1) Users of CAS ONLINE should do searches on common misspellings if their search depends critically on a specific word. (2) CAS ONLINE should significantly improve the editorial quality control on the actual entries of records into the data base. ~~~
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Literature Cited
William D. Hobey Worcester Polytechnic Institute Worcester. MA 01609
To the Editor:
Hobey is indeed correct in pointing out that asearch of the CAS ONLINE CA File for a term, especially a chemical substance name, may not always retrieve all pertinent citations. Misspellings do occur. This problem is not limited to the CAS ONLINE CA File, but may occur in all services whether they are computer-readable or printed. I t is important to note that a search in CAS ONLINE for a specific chemical substance should not he done on the name alone but by CAS Registry Number, which is the most comorehensive and vrecise way to search for a specific chemical substance. If only the substance names are searched, the results will be incomplete, in most cases. A search that includes the Registry Number, and in some cases substance names, will produce the most complete retrieval if the searcher is interested in identifying as many documents as possible that have cited the substance. We encouraee anv searcher of the CAS ONLINE files who wishes to c o n k c t comprehensive search to "Expand" the termk) of interest to see if there are anv missvellings on the file that should be taken into account in the search; this command will list other words on the index file with very similar spellings. I t may not highlight all misspellings, but it may provide some alternate terms. Chemical Abstracts Service does strive to provide the highest quality publications and services and toward that end has instituted a number of computer edits over the years to assure greater accuracy. We continue to develop additional wavs to maintain the inteeritv " " of the data base. We appreciate Hobey's comments and his efforts to alert users to nossible search difficulties. We hope that our additional recommendations will also help useis to improve the efficiency of their searches.
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David Welsgerber Chemical Abstracts Service P.O. Box 3012 C O I U ~ ~ UOH S .43210
Uslng Sand for Spill Cleanup Appears To Be a Step Backward In Technology To the Editor:
The article on the "AC Appruach to I.iquid Spill Cleanup" by Nelson II'J86.63, A16;] werlouks the fact thar there are a numlwr ot'lightwcight, highly efficient ahsvrbenrs that offer numerous advantaws over sand. Fur examvlr.. H.4ZORH. a sodium borosilicate glass, will absorb and retain 10 times as much liquid as sand and weigh a fraction as much. This certainly is an important factor in cleaning up a spill and subsequent disposal since a gallon spill would require over 20 lb of sand compared with less than 2 lb of this more modern absorbent. Although the author recommended sand as a general procedure, it certainly cannot he used on a spill containing hydrofluoric acid. Volume 85
Number 3
March 1988
281
New universal absorhrnts such as spun-bonded polvolefins and liquid neutralizers containing monoethanol amine offer advantages that should also not be overlooked. Donald D. Hedberg, President Lab Safety Supply Co. 3430 Paimer Drive P.0. BOX 1368 Janesville, WI 53547
1). nXn-'11 is obtained bv the resoective differentations and Xapproaches one so thai limit 0;" - 1)/(X - 1) = n because n(ln-1) = 1 for all n, and all of this is hecause In-' = n for all n. Proof of limit (X" l)/(A - 1) where (A" 1) = (A l)(X"-' A"-2 .. . A 1) also can be shown by mathematical induction. Case 1: (A - l)/(X - 1) when n = 1 is 1, Case 2: (X2- 1)/(X - 1) when n = 2 is 2, Case 3: (A3 - l)(h - 1) when n = 3 is 3. Now when n = k, (Ak - 1)/(X - 1) = (Ak-I hk-2 . . . X 1) = k. Finally, the case where n = k 1 is taken. The k 1term is added to both sides of the (Ak - 1)/ (A - 1) relation so that k 1 is the obtained sum. Therefore ( X k - l ) / ( h - l ) + X k = (Xk+Xb-1+Ak-2+...X1) =k+Xkis the result of addition and k Xk = k 1 because Xk = 1. Q.E.D. Q.E.D. or Quod Errat Demonstratum is a Latin phrase for "that which has been proved", but in free translation, it is "quit, enough done" or "quite easily done". The latter of the free translations applies to the above proof. ~~~~
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Although not touted as a universal spill cleanup procedure, the AC procedure can be used for safe, efficient cleanup of nearly all liquid chemical spills. The AC procedure is general, easy to learn and remember, quick and easy to carry out, very economical to implement and use, and in&insicaCy safe. Learning and practicing the AC procedure will help students and-laboratory workers understand the inherent faults of emergency cleanup procedures that emphasize direct deactivation of soilled chemicals. Note that t h ~ . A vp k d u r e ii very effective for cleanupof hvdmfluor~cacid spills. There is no visible evidence of any chemical reaction &hen sand absorbs 48%, 5 M, or 1 M solution. Any silicon tetrafluoride produced by the slow reaction of silica with the hydrofluoric acid probably reacts immediately to form fluorosilicic acid. Also, sand is a safe, efficient absorbent for hot, 70% perchloric acid, a very hazardous chemical that certainly could not be absorbed safely using "new universal absorbents such as spun-bonded polyolefins." Sand is the ideal absorbent for use with the AC orocedure. Sand is a very good absorbent for most laboratory liquids, even low-viscositv, volatile liouids. Sand is more dense than most liquids, ineit to nearly d l chemicals, readily available, and very economical to use. In short, sand is the best allaround absorbent for liquid chemicals spilled in the laboratory. Commercial absorbents and spill cleanup materials will find applications in specific cleanup situations, t u t the AC soill clc,anuu orocedure should be taueht and irn~~lemented as a progresi&e step in applied chemiial technol&y. Norman S. Nelson
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William D. Hlii Jr. NO^ Carolina Central Univenity Durham. NC 27707
Rethlnklng the Clement and Desormes Heat Capacity Ratlo To the Editor: Bv coincidence. we were orenarine a oaoer makine the 63, same point as that of Bert;& a n d - ~ i ~ o n a l[198i, d 2521. concernina the erroneous discussion and derivation of the'equation Gociated with the Clement and Desormes heat capacity . . ratio ex~eriment.The error was first Dointed out many years ago [1947,24,251], but apparently ~ k r t r a n d and McDonald are unaware of this reference. We would make two points beyond those in the more recent article: (1) There is no information whatever about the heat capacity ratio, per se, in the adiabatic expansion experiment. In the ideal gas approximation as presented by Hertrand and Mc1)onald. the thermal oronertv of the ras under study that determines the results bf t i e experiment is C,. nothine more or less. The ratio enters the discussion as a matter of convenience and depends on the assumption that C, - C, = R. which is not strictly true for real cases. (2) The e;roneous assumption of reversibility in theherivation of the commonly used ea 9, is completelv counteracted by the introductionbf an approximatik (truncation of the &arithmic expansion) rc.sulting in the pruperly derived eq 8! Edwin F. Meyer and George H. Stewart Texas Woman's University Dentan. TX 76204
Avogadro's Number: A Perverse View Comments on Euler's Theorem for Homogeneous Functions and Proofs Thereof To the Editoc The discussion of Euler's theorem with respect to thermodynamic functions by R. J. Tykodi (J.Chem. Educ. 1982,59, 557) and by Michael A. Adewurni (J. Chem. Educ. 1986, 63(7), 610) were and still are very interesting. There really should be no confusion about LCHospital's rule for any function involving a numerator and a denominator. This includes findine the limit of (An - l)/(A - 1) when X approachm 1. The deri\,'ati\.eof the n h e r a t o ; is divided hy the derivative of the dcn(miator and then evaluated to the limit. In many cases the differentations are executed many times before finding the limit, but in the case of (An- l)/(A 282
Journal of Chemical Education
To the Editor: Poskozim. Wazorick. Tiemoetoaisal. and Poskozim 11986. . . 63, I251 bring togethe; a usefui set of illustrations with a common ~ u r ~ o s e - t ohelo students (and their instructors?) compreh;ndthe size of ~ i o a d ~ r onumber. 's On reading this, I asked myself, perhaps perversely, what could he said to make Avogadro's number seem smaller than it does in such illustrations. Because 279is almost exactly 6 X loz3, if you start with one of anything and double it a mere 79 times, you have Avogadro's number of them. It's best to start with something small. Thomas A. Lehman Bethel College North Newton. KS 67117
