Averaee 'T'
Purification stage (12 obser- 'T' extremes % error
vations)
As isolated -0.72 -0.25; -1.01 34.1
First recrystallization -0.95 -0.84; -1.09 9.8
Second recrystallization -1.05 -0.99; -1.10 4.0
Third recrystallization -1.11 -1.08; -1.13 1.8
Fourth recrystallization -1.12 -1.10; -1.13 1.7
First resublimation -1.12 -1.11; -1.13 0.9
Second resublimation -1.122 -1.12; -1.13 0.7
It is obvious from Table I that for truly quantitative significance, thiotimoline purified as described must be used. After the second resublimation, for instance, the error involved in an even dozen determinations is less than 0.7%, with the extreme values being -1.119 seconds and -1.126 seconds.
In all experiments described subsequently in this study, thiotimoline so purified has been used.
Time of Solution and Volume of Solvent - As would seem reasonable, experiments have shown that increasing the volume of solvent enables the thiotimoline to dissolve more quickly - i.e., with an increasingly negative time of solution. From Figure 1, however, we can see that this increase in endo-chronic properties levels off rapidly after a volume of solvent of approximately 1.25 ml. This interesting plateau effect has appeared with varying volume of solvent for all varieties of solvents used in these laboratories, just as in all cases the time of solution approaches zero with decreasing volume of solvent.
Time of Solution and Concentration of a Given Ion - In Figure 2, the results are given of the effect of the time of solution (T) of varying the volume of solvent, where the solvent consists of varying concentrations of sodium chloride solution. It can be seen that, although in each case the volume at which this plateau is reached differs markedly with the concentration, the heights of the plateau are constant (i.e. -1.13). The volume at which it is reached, hereinafter termed the Plateau Volume (PV), decreases with decreasing concentration of sodium chloride, approaching the PV for water as the NaCl concentration approaches zero. It is, therefore, obvious that a sodium chloride solution of unknown concentration can be quite accurately characterized by the, determination of its PV, where other salts are absent.
This usefulness of PV extends to other ions as well. Figure 3 gives the endochronic curves for 0.001 molar solutions of sodium chloride, sodium bromide and potassium chloride. Here, the PV in each case is equal within the limits of experimental error - since the concentrations in each case are equal - but the Plateau Heights (PH) are different.
A tentative conclusion that might be reached from this experimental data is that the PH is characteristic of the nature of the ions present in solution, whereas the PV is characteristic of the concentration of these ions. Table II gives the values of Plateau Height and Plateau Volume for a wide variety of salts in equal concentrations, when present alone.
The most interesting variation to be noted in Table II is that of the PV with the valence type of the salt present. In the case of salts containing pairs of singly-charged ions - i.e., sodium chloride, potassium chloride and sodium bromide - the PV is constant for all. This holds also for those salts containing one singly charged ion and one double charged ion - i.e. sodium sulphate, calcium chloride and magnesium chloride - where the PV, though equal among the three, varies markedly from those of the first set. The PV is, therefore, apparently a function of the ionic strength of the solution.
This effect also exists in connection with the Plateau Height, though less regularly. In the case of singly charged ions, such as in the first three salts listed in Table II, the PH is fairly close to that of water itself. It falls considerably where doubly charged ions, such as sulphate or calcium, are present. And when the triply charged phosphate ion or ferric ion is present, the value sinks to merely a quarter of its value in water.
Solvent (Salt solutions in Plateau Height Plateau Volume
0- 001 M concentration) (PH) seconds (PV) milliliters
Water -1.13 1.25
Sodium Chloride solution -1.13 1.37
Sodium Bromide Solution -1.10 1.37
Potassium Chloride solution -1.08 1.37
Sodium Sulphate solution -0.72 1.59
Calcium Chloride solution -0.96 1.59
Magnesium Chloride solution -0.85 1.59
Calcium Sulphate solution -0.61 1.72
Sodium Phosphate solution -0.32 1.97
Ferric Chloride solution -0.29 1.99
Time of Solution and Mixtures of Ions - Experiments currently in progress in these laboratories are concerned with the extremely important question of the variation of these endo-chronic properties of thiotimoline in the presence of mixtures of ions. The state of our data at present does not warrant very general conclusions, but even our preliminary work gives hope of the further development of the endochronic methods of analysis. Thus, in Figure 4, we have the endochronic curve where a mixture of 0.001M Sodium Chloride and 0.001M Ferric Chloride solutions is the solvent. Here, two sharp changes in slope can be seen: the first at a solution time of -0.29, and the second at -1.13, these being the PH's characteristic of Fer ric Chloride and Sodium Chloride respectively - see Table II. The PH for a given salt would thus appear not to be affected by the presence of other salts.
This is definitely not the case, however, for the PV, and it is to a quantitative elucidation of the variation of PV with impurities in the solvent that our major efforts are now directed.
Summary - Investigations of the endochronic qualities of thiotimoline have shown that:
a - Careful purification of the material is necessary for obtaining quantitative results.
b - Increasing the volume of solvent results in increasing the negative time of solution to a constant value known as the Plateau Height (PH), at a volume of solvent known as the Plateau Volume (PV).
c - The value of the PH is characteristic of the nature of the ions present in the solvent, varying with the ionic strength of the solution and not varying with the addition of other ions.
d - The value of the PV is characteristic of the concentration of the ions present in the solvent, being constant for different ions in solution of equal ionic strength, but varying markedly with the admixtures of second varieties of ions.
As a result of all this, it is suggested that endochronic methods offer a means of rapid - 2 minutes or less - and accurate - within 0.1 % at least - analysis of inorganic, water-soluble materials.
Bibliography:
P. Krum and L. Eshkin. Journal of Chemical Solubilities, 27, 109-114 (1944), 'Concerning the Anomalous Solubility of Thiotimoline.'
E. J. Feinshreiber and Y. Hravlek. Journal of Chemical Solubilities, 22, 57-68 (1939), 'Solubility Speeds and Hydro-philic Groupings.'
P. Krum, I. Eshkin, and O. Nile. Annals of Synthetic Chemistry, 115, 1122-1145; 1208-1215 (1945), 'Structure of Thiotimoline, Parts I amp; II.'
G. H. Freudler, Journal of Psychochemistry, 2, 476-488 (1945), 'Initiative and Determination: Are They Influenced by Diet? - As tested by Thiotimoline solubility Experiments.'
E. Harley-Short, Philosophical Proceedings amp; Reviews, 15, 125-197 (1946), 'Determinism and Free-Will. The Application of Thiotimoline Solubility to Marxian Dialectic.'