EARLIER WORK OF GETMAN. 3 



of molecules of water, acts as a unit, or as one molecule in lowering the freezing-point 

 of the remaining water. But the total amount of water present, which is now acting 

 as solvent, is diminished by the amount taken up by the chloride or bromide molecules. 

 The lowering of the freezing-point is thus abnormally great, because a part of the water 

 is no longer present as solvent, but is in combination with the chloride or bromide mole- 

 cules. By assuming that a molecule of the halide is in combination with a large number 

 of molecules of water, it is possible to explain all of the freezing-point results obtained. 



"But the conductivity results must also be taken into account. These show unmis- 

 takably a marked degree of dissociation even in the most concentrated solutions 

 employed. There must, therefore, be a certain number of the molecules broken down into 

 ions, either by the water acting as solvent, or by the water in combination with the mole- 

 cules, just as salts are probably dissociated in their water of crystallization. 



"It should be observed in connection with the explanation we have offered of these 

 abnormal results, that the chlorides and bromides of the alkaline earths are generally very 

 hygroscopic substances, resembling sulphuric acid in their power of attracting water. 

 Some of them are, it is true, far more hygroscopic than others, yet, when dehydrated, 

 they all combine readily with water. It may be due to this property that they com- 

 bine with water to such an extent in concentrated solutions. 



"We do not put forward the above suggestion to account for our results as a final 

 statement of a theory, but only as tentative and subject to modification as new facts 

 are brought to light. It does, however, seem to account qualitatively for the experimental 

 facts which have been brought to light." 



Thus was proposed the present hydrate theory, which has been the guiding 

 thought in all of our subsequent investigations dealing with the hydrate 

 problem. 



Work of Chambers and Frazer. The work that was begun by Jones and 

 Chambers was continued, at the suggestion of Jones and under his guid- 

 ance, by Chambers and Frazer.* In the selection of compounds, those 

 were chosen, in general, which are characterized by being very hygroscopic. 

 Chambers and Frazer worked with copper sulphate, phosphoric acid, hydro- 

 chloric acid, sodium acetate, cadmium iodide, strontium iodide, and zinc 

 chloride. They obtained results of the same general character as those 

 found earlier by Jones and Chambers. The molecular lowering of the 

 freezing-point passed through a minimum, and then increased with the 

 concentration, acquiring in some cases for the most concentrated solutions 

 studied, a value that was larger than the theoretical value for complete 

 dissociation. 



The hydrate theory proposed by Jones accounted just as satisfactorily 

 for the results obtained by Chambers and Frazer, as for those previously 

 obtained by Jones and Chambers. 



Earlier work of GetmanJ The work that had already been done, showed 

 that the abnormally great freezing-point lowerings in concentrated solutions 



*Amer. Chem. Journ., 23, 512 (1900). 



tZtschr. phys. Chem., 46, 244 (1903). Phys. Rev., 18, 146 (1904). 



