Most analyses of organic blood components are presently performed by spectrophotometric methods. Recently, many

Values of Chemical Thermodynamic Properties," Part I, Natl. Bur. Standards Tech. Note 270-1 (1965).

mental results. Unfortunately, there is little information about the kinetics of such a reaction.Neither a pair of complexing agents nor one precipitant is superior throughout the rare earth series. One or more selective processes are operating. Somehow one rare earth cation is preferentially released in solution while the other tends to remain complexed. How this selectivity is achieved has not been deduced.

Densities of binary and ternary aqueous solutions of NaCI. NazSOd, and MgSOl have been determined from 25' to 175'. The solutions contained these compounds at concentrations corresponding to sea water and its concentrates up to fivefold concentration. A simple method of determining the densities of binary and ternary solutions is bared on apparent molal volumes of these compounds over a wide temperature range. Literature data on densities of sea water and its concentrates have been critically correlated. The method for estimating sea water densities uses the apparent molal volumes of the salt components of the sea water and a single interaction constant. A table of selected sea water density valuer gives the best values for the 25' to 150'C. temperature range for normal rea water and its concentrates.KNOWLEDGE of the densities of sea water brines, which contain primarily NaCI, Na2S01, and MgSO,, is important in the development and operation of an economic desalination process. Density measurements were made on aqueous solutions of these salts individually and in pairs a t concentrations varying from approximately those of sea water to a maximum fivefold increase, a t temperatures of 25" to 175" c.Several correlation techniques were used for evaluation of the experimental data. The empirical or semi-empirical techniques suggested by Mikulin (14). Zdanovskii (201, and Lengyel (11) were found to be complex and tedious, and that by Ezrokhi (3) was insufficiently sensitive. The data were satisfactorily correlated to the temperature and composition of the solutions hy a method based on the apparent molal volumes of the dissolved salts.The literature contains precise density data on sea water only a t or near room temperature. The reliability of the data, however, seems to diminish with increasi-lg concentration and temperature. Only sporadic density information is available above the atmospheric boiling point of sea water.A critical review of density data and the development of a computational method for the estimation of sea water densities in the entire range of interest were the further objects of this study. The correlations developed on the binary systems investigated were combined to yield a method for accurate calculation of sea water densities. The calculation method, and the comparison of experimental and calculated data along with selected values of sea water densities, are presented in this paper. EXPERIMENTAL METHODDensities were determined from a measurement of the volume of a known mass of solution using Lipkin pycnometers in the 25" to 75°C. temperature range (12) and dilatometer tubes from 75" to 175" C.

Experimental viscosity and density measurements are reported on ternary solutions of several electrolytes present in sea water, and on a synthetic sea water over the range of ionic strength levels from 0.7 to 3.5 and for sea water up to a concentration factor of 3 and the temperature range from 25' to 1 5 O O C . The experimental viscosity data were correlated with a precision of 0.2 to 0.3%, assuming an additivity of the constants of the Othmer rule. literature data were reviewed and compared with the correlation. Recommended sea water viscosity data are given as a function of temperature and concentration. KNOWLEDGE of viscosities of sea water and brackishwater brines, which contain primarily NaC1, KC1, Na2S04, and MgS04, is important in the development and design of economic desalination processes. In a previous paper (7) the viscosities of the binary mixtures were evaluated on the basis of the Othmer rule or relation based on the properties of a reference substance under a similar condition. The reference substance was water and the single similar condition was temperature.This paper presents viscosity measurements on ternary aqueous solutions and on calcium-free synthetic sea waters from 25" to 150" C., covering ionic strength concentration levels from 0.7 to 3.5. The experimental data were correlated with satisfactory precision, assuming an additivity of the constants of the Othmer rule.The experimental apparatus, method, and calculation techniques have been given (6, 7). EVALUATION OF EXPERIMENTAL DATAsalt was expressed by the Othmer rule ( I 1 ) : Ternary Systems. The viscosity of a solution of a single log qa = c, + m, log q . (la) Similarly, the relative viscosity, which has some advantages and is more frequently used, can be given as:where RR' is the relative viscosity of the solution, q s , / q , qsl is the viscosity of the solution, cp. qw is the viscosity of water a t the same temperature, cp.Bo, = m, -1 and Ao, = C, Ao, and Bo, are temperature-independent Othmer constants for compound i for the linear equation. These constants were expressed as functions of ionic strength in molal units in the forms Ao, = A1,I + A2,12 + Am13 (2) Bo, = B1,I + B J 2 + B3,13 (3) T o correlate the measured viscosities of two salts containing the Othmer constants of the mixture, A M and B M were calculated for each solution a t three constant ionic Present address: Research Foundation, Lowell Technological Institute, Lowell, Mass. 01854strength levels over the entire test temperature range. Since the concentration of the solutions under our test conditions increased somewhat a t high temperatures (this was caused by water evaporation into the vapor space of the closed viscometer system), the measured data were adjusted to constant ionic strength by graphical interpolation. Then, an attempt was made to plot the obtained A M and E M constants as a function of the mixture composition a t each constant ionic strength level. The composition of the mixture was expressed as ionic strength fraction with respect to the salt c...