[Surface activity of the extracts of the lungs and other organs]

Monomolecular surface films on the border-line of the "liquid-air" phases were observed to be formed in the water-saline extracts of the lungs and of the other organs. The surface films were compressed and extended on Wilhelmy's balance; the isotherm surface tension (ST)-square typical of the solutions of the surface-active materials (SAM) were recorded. Analogous curves with the minimum ST below 12 din/cm were recorded in testing the SAM monolayers placed on the liquid lining of the volatile solvent. Pulmonary surfactants differed from the SAM of other organs by the highest capacity to lower the ST in compression of the monolayer.