The effect of temperature upon the absorption spectr~ in the ultravio. let an~ part of the visible ranges was determined for several c~mpounds Jl1 aqueo~ls SOlutlOll. 1 e m.p e r~ tures used were 10 0 , 25 0 , and 40 0 C. The 1l1~ten al s used as solu tes JI1cludedbot h morgalllc and organic compounds, namely, potassium I1ltrate, potassIUm dIChromate, d lpl;enylsulfon e, diphenyl phosphate, 4,4'-diaminobenzophenone! and. m-creso]sulfonphthalem. As the temperature ,yas dec reased there was a n IIlcrease 111 l?aXlmU1l1. absorbance of all compol:llds except i n the case of dip henyl phosphate, the behavlOr of .WhlC!"t was anomalous. A slJght s hift of the absorbance curves also occurred. The relatlOns hlp betwee n absorbance and temperature was not linear in the temperature range i~v es tigated. The results showed that temperature shou ld be controlled within ± 2 deg. C If molar .absorbance values are to .be obtained within 0.5 perce nt. T emperature coeffiClents for an llldlvldua.l compound req uIre extensive absorption m easurements of that compound III k~lown medIa, and such coefficients wi ll hold for the sp ecifi ed wavelengths only under speC Ifi ed condItIOns. As a general guide the temperature shou ld be controlled to ± 0.5 d eg C.

The ultraviolet abso rp tion spectra of 4-chloro-4'-aminodiphenylsulfone has been determin ed . The d issociation m ay be considered as the acidic dissociation of the ammonium ion which is form ed with t he a ddition to the base of hyd rogen ion from an acid s uch as hydrochloric acid. Spectrophotometric m easurements of sevcral concentrations of 4-chloro-4'-aminodiphenylsulfon e at variolls known h ydrogen-ion concentrations were made at 25° C, from which t he values pK., based upon the concentrations, were determined. From these, the value of pKa was derived. At 25° C, pKa is 1.38, which corresponds to a value of 0.042 mole per li ter for K a. The activity coefficient terms may be expressed simply as a linear function of the ionic strength . Spectrophotometric m casurem e nts were a lso made at 15°, 20°, 25°,30°, and 35° C on certain solu tions in order to calculate the h eat of d issociation. It was found to be 21,000 joules deg-I mole-I. The basic di~soc i ation co nstant, l( b, i~ 2.4 X 10-13, or pKb is 12.62 .