The results of further development of the method for determining the optical density and the concentration of solutions. Developed a working model of the device. In order to automate the scientific experiment designed software system to control the layout and processing of the measurement results. As a result of the statistical approach to the processing of significantly improved accuracy and reliability of the results. The test method for testing aqueous solutions of salts LiBr, CaCl2, NaCl, KCl. The developed method is applied in the study of absorption of water vapor flowing liquid film aqueous LiBr.