A Modification in the Compensating-Type Gouy Tube The Gouy method is a frequently used procedure to determine the magnetic susceptibility of paramagnetic substances in solution.' An alternative method for determining magnetic susceptibilities in solution has been described by Evans2and recommended as appropriate for the undergraduate laboratoryY however, it utilizes equipment (proton nmr) which may be unavailable. The Gouy method is simpler conceptually and more clearly demonstrates classics1 principles. The utilization of a comoensatine ,. Gouv . tube5 eliminates several sources of error inherent in the rxpcrimwt. c 6 , thr nrcesclty t u wrrrcr t'or rhr d~nmngnrtlsmof t h glncs ~ nnd solvent. The wual rumpma;iting-t\pe Gouy rube hm a rlgd fillrr tuhr rhnugh whwh all liquids mtnrlurrd into or rrmuacd trum the Ihrrcomparrment murr p a i s Emprwng and flllinr: this rompensating irotim iitcdiuu.atd requires considerable care since the seal around the filler tube is quite fragile. The figure shows a modification in the design of the compensating Gauy tube. The filler tube has been isolated in a separate piece with ground glass joints, enabling the lower compartment to be emptied, cleaned, and filled with ease before the air trap and filler tube are replaced. Experiments with tubes incorporating this modification are less time consuming and tedious.
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'Figgis, B. N., and Lewis, J., "Magnetocbemistry" i n "Techniques of Inorganic Chemistry" (Editors: Jonassen and Weissberger), Vol. IV, Interscience, New York, 1965. PEvans, D. F., J. Chem. Sac., 2003 (1959). Qeutscb, J. L., and Poling, S. M., J. CHEM. EDUC., 46,167 (1969). 'Crawford, T. H., and Swanson, J., J. CHEM. EDUC., 48,383 (1971). "elwood, P. W., "Determination of Magnetic Susceptibility", i n "Physical Methods of Organic Chemist-" (Editor: Weissberger), Third Edition, Interscience, New York, 1950, Val. 1, Part IV, p. Kent State University Kent, Ohio 44242
J u l i a B. Zimmerman Norman V. Duffy
Volume 54, Number 10. October 1977 1 613
