3<W 



Solubilities of Diethylamine and Water. 



German) to peal off in visible scales when heated to 150°- 



160 c ." 



An experiment with M tiller's new "Resistance" glass 



showed that even the slightly greater solubility of this glass 



as compared with Jena glass caused a lowering of the tem- 

 perature of over 2°. 



It seems therefore probable that the present results are 



slightly vitiated by the solution of glass, but the extreme 



insolubility of Jena glass makes it likely that the inaccuracy 

 due to its solution is but slight. 



It is interesting to note that the form of the curve is more 

 that of the curve for trimethylpyridine (Rothmund, Zeit. 

 Pliys. G'Aem.xxvi. p. 4:62, 1898) than of that for triethyl amine 



(ibid. p. 461). 



An attempt was made to determine the densities of saturated 

 solutions of the amine and water at various temperatures by 

 heating a solution containing 40*5 per cent, of amine in a 

 graduated tube and observing the volumes of the layers at 

 various temperatures ; the weights of the layers being 

 calculated from the percentage composition of the saturated 

 solutions as read off from the solubility curve. The attempt 

 proved abortive since the values obtained are so largely 

 affected by small errors in the data used ; it was, however, 

 obvious that there is (1) practically no sudden change in 

 total volume on separation, and (2) very little difference in 

 the densities of the two saturated solutions which are in 

 equilibrium at temperatures between 143°*5 and 153°. 



Experimental Details. 



Suitable quantities of water and diethylamine were weighed 

 out from "weighing pipettes'" into a small stoppered bottle. 

 The mixture so made was transferred as soon as possible to a 

 tube sealed at one end and drawn to a capillary in the middle ; 

 by changes of pressure the liquid was got into the lower part 

 of the tube, which was then sealed off at the capillary. 



A tube so prepared was heated in a paraffin bath so 

 arranged that the filament of an incandescent electric lamp 

 could be viewed through the tube. The appearance of a fog- 

 was very easily seen in this way, and consequently the 

 temperature at which the mixture under observation separated 

 into two layers could be ascertained with a fair degree of 

 accuracy. The tube was supported by a simple mechanical 

 device whereby the contents could be remixed between 

 observations without removing the tube from the bath. 



Oxford, May 1905. 



