Polymer Credits To the Editor: In the article "Polymer Science and Engineering Education in the United States," by J. C. Salamone, R. D. Deanin, M. G. Young, and E. M. Pearce, [J. Chem. Educ., 50, 768 (1973)] surveying polymer science and engineering course credits and programs for the academic year 1971-72, I would like to correct the information listed for course credits in Table 1 for Newark College of Engineerins. ----The course credits should read as follows: Total Course Credits, 1971-72: 21; Departmental Credits: Chem. Dent. 15. Ch.E. Dent. 6: Course Credits: Polvmer Science, ~'nderg;aduate3, ~ i a d u i t e6; Polymer ~ngine&ing, Graduate 6; Structureand Properties, Graduate 6. ~
The courses offered under these headings are the same for the current academic year (1973-74). William H. Snyder Newark College of Engineering Newark, New Jersey 07102
the stainless steel cannula is replaced by a disposable plastic pipet tip [Blackman, D. and Sanchez, G. R., J . Chem. Educ., 50, 851 (1973)l. Implicit in that note was the fact that the total volume dispensable was limited by the capacity of the plastic tip, generally 1 ml. We have now. overcome this limitation by nesting a number of ~ i ~tius. e t one inside the other, at the end of the syringe, t h k r e b i expanding the capacity of the apparatus. For maximum efficiency, the constricted ends of all tips other than the outermost are cut off before nesting. As many as five tips have been used in this way without rendering the set-up too unwieldy, allowing delivery of a maximum volume of approximately 4.8 ml. No loss of precision is introduced by this modification: using a 5-ml syringe, replicate n1innot.a of water volume 3.0 ml were ..--... .-distilled ~ ~ - - ~ - ~ -of ~ dispensed and weighed, yielding a relative average devia. tion 0.21%. ~ - of ~- ~ ~ while at a nominal volume of 5.0 ml the relative average deviation dropped to 0.12%. Supported by the Division of Chemical Education-du Pont Small Grants Program of ACS and by MSBS Support Grant RR 0800501 from the General Research Support Grant Division of Research Resources, National Institutes of Health. Address correspondence to D. B. ~~
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/ Journaiot Chemical Education
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Christine A. Roberts Giselle C. Bowman David Blackman
Pipet Modification To The Editor: A recent communication from this laboratory described a modification of the Comwall pipetter in which
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Federal City College 1321 H Street, N.W. Washington, D.C. 20005
