REPORT OF THE SECRETARY 121 



It will be noted, in this roughly chronological discussion of the 

 work of the year, that the only experiments mentioned came under 

 the first head of direct experimentation on living organisms. Some 

 jjrogress, however, has been made under the second head in the sub- 

 division dealing with molecular structure. Due to the lack of funds 

 und shop facilities, it was impossible to undertake any of this work 

 at the Smithsonian. The only steps taken in that direction were, 

 first: The construction of two large tanks which will be used for 

 vacuum spectrograph bodies, and, second, the provision of special 

 room space in the reconstruction of the basement. Fortunately, 

 however, through the very generous cooperation of the Fixed Nitro- 

 gen Laboratory, work begun at the Fixed Nitrogen Laboratory by 

 Doctor Brackett during the four months previous to his appoint- 

 ment by the Smithsonian, has been continued during the past j'ear. 

 Mr. Liddel, appointed as a junior chemist on its staff, has actively 

 ])ushed the research work contemplated under the direction of and 

 in cooperation with the Smithsonian. The first work undertaken, 

 namely, the study of the near infra-red absorption spectra of the 

 halogen derivatives of benzene, has been carried through to comple- 

 tion so far as available materials and equipment permit. Predic- 

 tions made in the study of the paraffines in regard to the wave-length 

 position of the absorption due to vibration of hydrogen with respect 

 to carbon, have been borne out in the case of the phenyl derivatives. 

 Tiie position of the second overtone of this vibration promises to 

 furnish an interesting basis for determinating the binding forces 

 ui)on the hydrogen atoms in different positions in the various organic 

 compounds. The work will be extended during the coming year, 

 largely to nitrogen compounds of a more immediate interest to the 

 Fixed Nitrogen Laboratory, and, at the same time, of great impor- 

 tance in biological connections. 



Photochemical work bearing on biological problems can not be 

 undertaken until additional financial support can be obtained. In 

 the infra-red spectroscopic anal3'sis, undertaken at the Fixed Nitro- 

 gen Laboratory because of its bearing upon the problems of molecular 

 structure, the range of spectrum which can be studied is limited by 

 the transmission of glass of wliich the prisms are constructed. It 

 has been the plan to build, at the Smithsonian, spectrographs in 

 which prisms of salt will be used. This will permit the extension 

 of the infra-red investigations from 2V2/A to Ibfi. A more complete 

 understanding of the structure of polyatomic molecules Avill depend 

 upon securing the information from these regions of longer wave 

 lengtlis, as the most complete i)os.sible data upon vibration wave 

 lengths must be secured if progress is to be made. The actual con- 



