To the Editor: I am sure the method devised by Mr. 1LZ. Rmfeld for making Teflon-to-glass connections (J. CHEM. EDCC.,44, 303 (1967)) xould be satisfactory for many applications. However, there is a Teflon tubing on the market which is specifically designed for this use. This tubing i:! called "Flo-Tite" and is marketed by Pope Scientific, Menomonee Falls, Wisconsin. "Flo-Tite" works like this: An exterior tube of heat-shrinkable Teflon T F E is lined with a tube of Teflon FEP. The F E P melts a t a lower temperature than the TFE. Therefore, when heat is applied to the tubing (about 62SoC) the F E P will melt while the T F E shrinks around it, forming a tight and permanent seal. "Flo-Tite" tubing has many advantages. It can be used on tubing of almost any material, including glass, metal, or ceramic. And the tubing need not be tapered. The "Flo-Tite" tubing can be removed simply by slie tiog with a razor blade and peeling off. I hare used this Teflon tubing in our laboratory and have found it to be useful for many applications, and hope t,liir lett,er will aid other cliemists who use Teflon tubing. EUGENEC. JADD
plex phenomenon in terms of point by point mathematical evaluation. Unfortunately, there are minor drawing errors in Figure 12, which also appears on the cover of the JOUR~TAL. I t is certain that this type of computer technique is going to be used more and more as a teaching aid both in graduate and undergraduate levels. We, for example, in the Chemistry Department of this Institute are already using analog computer methods for solving problems in a graduate course on chemical kinetics vith much success. P. Ii. GHOSH
IYDIAS ISSTITCTE OF TECHNOLOGY Ihnpur, India
T o the Editor: Mr. Ghosh's note about the corrections in Figure 12 is correct. I apologize to the readers and am most grateful to Mr. Ghosh for pointing out t,he error. The corrected passage should read : The output from potentiometer 7 should read - U(x)$/10k. It should enter amplifier 6 with a gain of 10 and the total output of amplifier 6 should be +/k U(X)). I hope the attention of all potential users can be called to this erratum. I might add that I am surprised and delighted that an Indian school should be so well equipped in this field. They are certainly better off than many American colleges. FREDERICK D. TABBUTT
(-w+
To the Editor: The article by Dr. Frederick D. Tabhutt on "The Use of Analog Computers for Teaching Chemistry" (J. CHEX.EDUC.,44, 64 (1967)) is an excellent account of what a transistorized analog computer can do for chemistry students and teachers, particularly in problems n.liere it is cumbersome and difficult'to illustrate a com-
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