346 CARNEGIE INSTITUTION OF WASHINGTON. 



A number of improvements have been made in the apparatus, thereby 

 enabUng a single observer to make all the necessary adjustments in 

 addition to taking the deflection readings. This proved to be a 

 decided advantage, as it permitted Dr. Hutchinson to devote his 

 entire time to the preparation and analysis of the various solutions 

 used in the investigation. The cells were also somewhat modified to 

 adapt them to the alcoholic solvents. 



The results obtained by Dr. Hulbert and his co-worker indicate 

 that, in general, the molecular absoi-ption coefficient (A) is not a con- 

 stant, but either increases or decreases with dilution and in some 

 cases decreases to a minimum and then increases. This deviation of 

 A from a constant value is usually comparatively small, except for 

 some solutions at certain points in the spectrum, which were generally 

 found to be situated at the edge of absorption bands. 



The variation of A with the concentration has already been explained 

 in a qualitative manner by previous investigators in this laboratory as 

 due to the formation of complexes or "solvates" between the solvent 

 and solute, but it is pointed out, as a result of this investigation, that 

 such an explanation must be couched in mathematical terms before 

 attempting to apply it to the interpretation of quantitative data. 



Dr. Lloyd and Dr. Pardee have extended the work in absolute 

 ethyl alcohol to include a study of the limiting conductivities of the 

 sodium salts of organic acids in this solvent. The inability of previous 

 investigators to obtain experimental values for the equivalent con- 

 ductance of the organic acids at infinite dilution led them to under- 

 take the problem in the hope of eventually developing Aq for these 

 acids from the data obtained from their salts. 



A very accurate and convenient method for preparing the solutions 

 of these salts in absolute alcohol has been worked out and in the 

 subsequent measurement of their electrical conductivity a high degree 

 of accuracy has been attained. This has been made possible by 

 improvements in the conductivity method. Data have been obtained 

 on sodium salts of about 30 of the organic acids; this practically covers 

 the field of available compounds, owing to the insolubility of a great 

 number of the acids and their salts in absolute alcohol. The con- 

 ductivity values are all of the same order of magnitude, there being 

 little difference between the aliphatic and the aromatic derivatives 

 or between the different substituted compounds of the benzene series. 

 Although measurements were made at as high as 20,000 liters dilution, 

 Ao was not obtained experimentally, but was calculated by extrapola- 

 tion formula?. Other investigators in this field have attempted to 

 use the Kohlrausch fonnula for this purpose, although its appli- 

 cability to non-aqueous solvents has been seriously questioned. The 

 present investigators attempted to apply this formula to their data, 

 but with such widely divergent results as to preclude its usefulness.. 



