For the purpose of transferring hydrating lines, the author conducted a series of experiments on mixed hydrating agents, especially with respect to the equilibrium condition of hydrate formation. The results obtained were as follows: 1. In the mixed hydrating agent systems such as R-12 with R-21 or R-21 with R-22, both the hydrating lines and the condensation lines lay between those of component hydrating agents of mixed system. Even in an unstable area, one hydrating agent was packed into cages formed by the other agent, and thus the former contributed to the stability of the latter lattice. 2. In azeotropic mixture, hydrate was formed athigher pressure than those of component gas hydrates. Mixed ratio, at which the highest pressure was shown, agreed with the ratio of azeotropic mixture. 3. When help gases were added to R-12, they were packed into smaller cages of structure II, showing their stabilizing effect to it. The effect varied with temperature, causing curvature on the hydrating lines.
The authors applied the Fujiwara reaction, which is employed for the determination of chloroform and other polyhalogen compounds, to the determination of micro amount of dichloromonofluoromethane (Freon-21) dissolved in fresh water. When the squeous solution of Freon was heated with some appropriate amounts of pyridine and sodium hydroxide at 40°C for 15 minutes, the mixture indicated reddish color with the sbsorption maximum at 525mμ. This absorption had been used by some other authors in the past for the colorimetric determination of polyhalogen compounds. However, the above color was not very stable and gradually disappeared when it was heated successively. Then, the authors obtained an absorption at 366mμ which was more stable and sensitive than that at 525mμ. Thus, the determination of Freon was carried out as follows by estimating the absorbance at 366Mμ 20ml of aqueous solution containing more than 2μg of Freon was gently mixed with 9 ml of pyridine and 1 ml of 5 N sodium hydroxide, and the reaction mixture was heated at 50°C for 50 minutes. After it was cooled, the absorption at 366mμ was measured. This method was applicable to the determination of 0.1mg/l-7.0mg/l of Freon within the relative standard deviation of 1.0%. Also, its interference with dissolved metals were examined, and magnesium, calcium and copper were found to decrease their recoveries to some extent (Table 2).
The analytical method of dichloromonofluoromethane (Freon-21) reported in our previous paper was modified for the determination of Freon dissolved in sea water and brine. When the method described in previous paper was spplied to sea water or brine sample, the decreased recoveries which were found to be due to the precipitation of magnesium hydroxide were observed. The interference by magnesium could be partially settled by increasing the amount of sodium hydroxide which was used 1 ml of 5 N solution for the determination of Freon dissolved in fresh water. Satisfactory recoveries were gained by using 1.5 ml of sodium hydroxide to sea water containing 5-25g/l of chlorine and 2.0ml of sodium hydroxide to brine containing 20-45g/l of chlorine. In these cases, it was noted that the calibrations should be made to the known amounts of Freon dissolved in sea water (15g/l of chlorine) and in brine (35g/l of chlorine)(Fig.4). This modification, however, was not applicable to the brine of higher concentration and to those solutions containing c uprous or ferric ions more than 1mg/l which caused the decline of recoveries as described in our previous paper. It was also found that Freon could easily be expelled from aqueous solutions by aeration and absorbed quantitatively with ice-cooled pyridine by using the apparatus shown in Fig.5. Nine ml of pyridine were pipetted to each of the two absorption tubes kept in the ice-cooled bath. After 20 minute aeration of sample tube with a rate of 30ml/min., 20ml of 5N sodium hydroxide were added to the absorption tubes, and then the reaction was carried out as reported in our previous paper. As the result of our repeated experiments, 93% of Freon was found in the first absorption tube and the remaining 4% in the second tube. Any inhibitory effects of concentrated chlorine, magnesium and other metals were not observed, and this method was confirmed to be applicable to a wide-ranged purpose.
Basing upon the heat of formation, the number of hydrate and the crystal density previously measured and reported, the author made a comparison of the structure I with the structure II, and reached the conclusion that the structure II hydrate could more easily crystalize than the structure I and that as the number of hydrate increased the former was superior to the latter when used in the hydrate cycle. By using the boiling point and the critical temperature of the hydrating agent, the author could draw a graph, which is accurate enough in practical use to determine unknown temperature and pressure of hydrate formation.