A study of extremely pure dipalmitoyl-phosphotidyl choline (DPPC) by thermal analysis and x-ray scattering has revealed several features not reported previously. The experimental observations were very sensitive to sample purity and experimental procedure. Nevertheles~ reproducible results have been obtained. From both single domain and pov,;der x-ray patterns i.Ve have shown that the dry region of the diagram [% water, T] exhibits some phases characterized by a three-dimensional order. The study of the diffuse scattering has permitted us to improve the knoHledge of the LO phase and from the poHder patterns we have deduced the existence of several novel structural features such as a three-dimensional "LB 1 11 phase or phase transitions in the high temperature phase region PO + Qa.

No abstract

No abstract