Further Studies on the Hydrates of Sodium Thiosulphate.

Abstract

315equivalent of silver. There is also a memoir by Reuterdahl' on electrochemical equivalents and atomic weights.Makower2 has attempted to determine, from their rates of diffusion, the molecular weights of the radium and thorium emanations. For the radium emanation he finds the values 85.5, 97, and 99, assuming the substance to be monatomic. The thorium emanation is but slightly different. Makower suggests that the emanation may fill the vacant place in the periodic table between molybdenum and ruthenium, The atomic weight of radium itself has been discussed by Jones,B who, from a critical examination of all the evidence, is inclined to favor the higher of the two rival values, namely, Ra = 258.On the calculation of atomic weights, there is an interesting paper by J. Meyer.' An important suggestion by LutherJ is to refer combining weights, through the aid of Faraday's law, to the C. G. S. system of units. In this way the question of standards might be settled, and a rational table devised.

Anhydrous sodium thiosulfate as a primary iodometric standard

“…The curve in Figure 1 shows no inflections corresponding to different hydrates as claimed by Duval (5). Indeed, the well-known superheating and supercooling phenomena in the Na2S203-H20 system (6), as well as the water gradient produced in the dehydrating crystals, would preclude any such stoichiometric inflections in an inhomogeneous system. Solvent Dehydration of the Pentahydrate.…”

Transition Temperatures of the Hydrates of Na2SO4, Na2HPO4, and KF as Fixed Points in Biomedical Thermometry

“…Of particular significance to biomedical researchers is the gap from 35.36 to 50.664 °C. A literature search for salt hydrate transitions has produced the supplemental list shown in table 2 [31][32][33][34][35][36][37][38]. These systems were considered to have potential as temperature fixed points to fill the gaps in table 1.…”

“…This behavior may reflect the presence of several metastable phases, as indicated by its phase diagram [36]. It was difficult to initiate the formation of zinc nitrate hexahydrate, although once started, the transition temperature appeared quite stable.…”

“…Two additional salt: water systems were surveyed: (1) the FeCI 3 : H 2 0 system, which has a phase diagram [40] qualitatively similar to that for Zn(N0 3 )2 : H 2 0, and (2) the sodium thiosulfate system, Na2S203 : H20, which has a very complex phase diagram [36,37,40] with several metastable phases in a small temperature range about 48 °C.…”

Thiosulfates

“…The monohydrate [55755- and the heptahydrate [36989-91-0] are also known. Although 16 different crystalline modifications have been identified (24,25), the α-pentahydrate is the stable form below 48 • C. Solutions of sodium thiosulfate in the absence of seed crystals can be easily supercooled below their normal crystallization temperatures. The dotted line extension of the dihydrate phase in Figure 1 is an indication that, if supercooling takes place below this line, solutions normally giving the pentahydrate may form the dihydrate [36989- instead.…”