Conductivities and Viscosities in Formamid. 17 



formate heated for several hours to 180 in an atmosphere of ammonia. 

 In distilling the resulting brownish liquid under diminished pressure, 

 a yield of 80 per cent of the theoretical was obtained. At lower pres- 

 sures (0.5 to 2 mm.) a better yield resulted, since in this way the thermal 

 decomposition was reduced to a minimum. 



PREVIOUS WORK IN FORMAMID. 



Until quite recently no investigation of the physical-chemical prop- 

 erties of this remarkable liquid had been made. A brief sketch of the 

 recent work is given below. 



In his preliminary paper on organic solvents, Walden mentions the 

 marked similarity of formamid to water as compared with other liquids 

 in its solvent action on inorganic salts, and in later papers he records 

 some of its physical constants in comparison with other amids and with 

 water, viz, the dielectric constant and association factors, 1 specific 

 conductivity and molecular conductivity of the normal electrolyte 

 N(C 2 H 5 ) 4 I, 2 and the viscosity. 3 All of these constants were obtained 

 with a product which, as will be shown later, was far from pure, although 

 it may be pointed out that the first two constants are not appreciably 

 affected by small changes in the purity of the solvent. 



Turner and Merry, 4 in their work on the molecular composition of 

 trivalent nitrogen compounds, pointed out that the high association 

 factor of formamid is one of its most striking characteristics, and they 

 observed its similarity to water. They noted also that the association 

 of formamid diminishes more rapidly with rise in temperature than that 

 of water, and suggested that the solvent power for salts was largely due 

 to its high molecular complexity. 



Somewhat later, Walden, 5 in a study of the temperature coefficient 

 K, for organic liquids in the Ramsay and Shields equation for molecular 

 surface-tension, found that in the case of formamid the value was far 

 below that for non-associated liquids (2.12), having only the value 

 0.594 to 0.710; from these data he obtained an association factor in 

 close agreement with that as determined by Turner and Merry. 4 



Dunstan and Kassel, 6 while determining the fluidity of various binary 

 mixtures, measured the viscosity of mixtures of formamid and t'-amyl 

 alcohol at both low and somewhat elevated temperatures, and noted a 

 pronounced minimum in the fluidity curves at about 60 to 70 per cent 

 of formamid at both temperatures, and also a slight maximum at about 

 10 to 20 per cent formamid for the lower temperature. 



Rohler 7 studied the solvent properties of formamid for organic salts 

 and also the electrolysis of its solutions. He compared the density 

 with that of water above the freezing-point and found no minimum, 



t. phys. Chem., 46, 145, 175 (1906). 2 Ibid., 54 179 (1905). 3 Ibid., 55, 230 (1906). 

 Mourn. Chem. Soc., 97, 2076 (1910). 

 'Zeit. phys. Chem. ,75, 555 (1910). 6 /6{d.,76,367 (1911). 7 Zeit.Elektrochem., 16,420(1910). 



