air bleeder to control the vacuum and, hence, the evaporation rate. Part C is a %liter flask fitted with a sampling tube equipped with a 2mm. stopcock having a plug of Teflon. All ground glass joints were greased with a silicone stopcock grease, especially when vacuum was applied. Operation. The method of operating this apparatus depends upon the nature of the liquid to be dehydrated. For solvents or solutions which distill readily without decomposition, a voltage-controlled electric heating mantle is recommended as a heat source. For others, a temperature-controlled bath is required. The flask C is filled two-thirds to three-fourths full with the liquid to he dehydrated. A rubber septum inserted in the outer end of the sampling tube was found convenient for the removal, by means of a hypodermic needle, of samples for analysis and for use. The heating mantle around C is adjusted so that steady evaporation, condensation, and siphoning take place without flooding. A shorter return flow tube from the Molecular Sieve compartment can be used to reduce hold-up somewhat, although the tube should be high enough to serve as a vapor trap. Results and Warning. I n testing this apparatus with 0.1M nickel per-
chlorate in 1-butanol, i t was observed that when the dehydration had proceeded for about 4 hours, spurts of flame occurred and black products formed on the hot glass above the liquid in flask C. Apparently the higher water content present earlier had been sufficient to quench the oxidieing action of the perchlorate since in many earlier experiments such reaction had never been observed. When the dehydration was performed a t reduced pressure with a water hath a t 45O C. replacing the heating mantle, no difficulty was encountered with either nickel perchlorate or copper(I1) perchlorate. The efficiencyof drying was measured by titrations with Karl Fischer reagent, the procedure employed estimated as being able to determine as little as 0.0005% water. Results were as follows. A 0.1M 1-butanol solution of nickel perchlorate containing originally 0.81370 water by weight was found, after six hours‘ treatment employing the vacuum technique, to contain so little water that all that could be said with certainty was that it was between aero and 0.000570. With %propanol containing 0.28% water and no salt, 4 hours treatment reduced the water to 0.0014%; 6 hours dropped it to less
than 0.001%, and 10 hours dropped it t o between 0.000570 and zero. It would he expected that the dehydration should he more rapid with liquids of higher hailing point. This undoubtedly partly explains why 2 propanol required a longer time than did 1-butanol. (A reviewer of this paper has pointed out that the formation of a butanol-water azeotrope containing 42.5% of water and a %propanol-water azeotrope containing less than one third as much water probably contributes even more to the greater ease of dehydration of 1-butanol solutions compared to %propanol solutions.) LITERATURE CITED
(1) Arthur, P., Lyons, H., ANAL.CHEM. 24. 1422 (1952). (2) Carley, D. A,, M.S. Thesis, Oklahoms. State University, May 1964. (3) Hatch, L. F., “Isopropyl Alcohol,” pp. 11-12, McGrm-Hill, New Yark, 1961. (4) Hemh, C. K., “Molecular Sieves,” pp. 73-9, Reinhold, New York, 1961. (5) Jolly, W;, L., “Synthetic Inorganic Chemistry, pp. 121-3 and cited references, Prentice-Hall, Englewood Cliffs, N. J., 1960. A s s n u c ~ ~ in o part fmm the Ph.D. thesis of W. M. Heynes, Oklahoma State University, May 1966.
Recording Photometer for Monitoring Ultraviolet Absorbing Effluent from Chromatographic Columns Joseph F. Vincent, The Woman’s College of Georgia, Milledgeville, Ga.
HE lSbTRUIltNT
clrLrribed hrrr
Was
Tsperifirally drsignivl to monitor r~ir protein etTiuvnt from a chroniatogrn1ihic rolumn in nrdrr t u rerover sprritic frartions, hur ir might bi, uird IO moniror any ultrariolrt absorbinc: rffluent from a rhromarograpliir rolunin or ion exrhange rolunin. l’h Iihotmnrirr is a dotilh-hram type which minimizes flurtuations
