WHEN aqueous solutions of potassium f errioxalate are insolated by light from a quartz-mercury lamp, decomposition takes place LLR follows : 2K3Fe(C,04), -+ 3K&:,04 + 2FeC,O, + 2C0,. The difficultly soluble ferrous oxalate is precipitated, but this can be prevented if a sufficient concentration of potassium oxalate he added to the original solution. No quantitative investigation of this reaction has been hitherto carried out, although the corresponding photolyses of potassium cobaltioxalate (Vranek, 2. EleEtrochem., 1917, 23, 336) and of potassium manganioxalate (Cnhosh and Kappanna, J . Indian Chem. Xoc., 1926, 3, 127) have received attention. Draper (Phil. Mag., 1857,14, 161) showed that solutions of ferric oxalate itself undergo a similar decomposition in light, and suggested its application in photometry; and work has also been published on the closely related interaction between solutions of ferric chloride and oxalic acid in light, more particularly by Lemoine (Ann. Chim., 1895,6,433) and, very recently, by Kornfeld (2. Elektrochem., 1928, 34, 598). Kornfeld's results are of quite a different nature from ours, whereas Leinoine's are, in some respects, similar. Experiments are in progress in this laboratory on the factors which cause the one type of reaction to change over to the other. In the meantime, the present paper contains essentially the results of an investigation of the energetics of the potassium ferrioxalate decomposition, which are discussed in the succeeding paper.Preliminary Experiments.-As it was hoped to experiment with solutions of the free ferrioxalic acid, ferric oxalate was prepared by the action of an excess of freshly precipitated and washed ferric hydroxide on aqueous oxalic acid. A week's standing at the ordinary temperature with occasional shaking was necessary for neutralisation. After filtration from the excess of ferric hydroxide, the greenish-yellow solution was evaporated on the water-bath. The syrup produced finally set to a yellowish-green, transparent', hygroscopic solid, which gave analyses corresponding closely to the formula Fe,(C,O&.The ferrioxalate was prepared by mixing solutions of potassium oxalate and ferric chloride in the molecular ratio 3 : 1, and precipitating the salt with alcohol. The emeraldgreen crystalline powder, once recrystallised, on analysis corresponded closely to the formula K,Fe(C20&,3H,0. Preliminary insolations of solutions of these substances were then

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When this work was commenced, very few data on the conductivities of mixtures of electrolytes were available. During the time the experiments were being performed, or since their completion, contributions by Stearn (8) and by Ruby and Kawai (7) appeared.Our experiments involved the determination of the electrical conductivities at 25°C. of solutions of potassium chloride, sodium chloride, and SUMMARY 1. The electrical conductivities, densities, and viscosities have been determined at 25°C. for solutions of potassium, sodium, and lithium chlorides in water and in one-tenth molar hydrochloric acid. The weight concentrations of the alkali metal chlorides were varied between about 0.1 M and upper limits of 3.8 to 5.8 M.2. The dependence of the equivalent conductivity-viscosity product on the concentration of the alkali metal chloride, dissolved either in water or in 0.1 M hydrochloric acid, is discussed in the light of the views of Bernal and Fowler on the nature of the viscosity of electrolytic solutions.The junior author wishes to acknowledge with gratitude the grant given him by the Department of Scientific and Industrial Research while he was a student in training.