362 BULLETIN OP THE UNIVERSITY OF WISCONSIN. 



acid was prepared by redistilling the first sample from a water- 

 bath kept at 30° C. The gas was again passed through the dry- 

 ing tubes and condensed as before. Measurements with this 

 sample gave the same readings for maximum resonance as in the 

 first case. The temperature coefficient is negative, but it was 

 not accurately determined. 



Acetonitrile. — The sample of acetonitrile first measured was 

 obtained by distilling a sample of Kahlbaum's make. Its boil- 

 ing point was very constant, being 80.9° C. under a pressure of 

 745 mm.. The average of four determinations gave the value 

 36.5 for the D. C. at 21° C. 



A second sample, prepared by Prof. Kahlenberg from the 

 Kahlbaum preparation by dehydrating it with phosphorus pen- 

 toxide, and redistilling twice, was measured. Its boiling point 

 was 80.7 under a pressure of 749 mm. The measurements were 

 made at 22° and gave the same result as was obtained with the 

 first sample. 



A third sample, also furnished by Prof. Kahlenberg, was 

 finally measured. This sample was twice dehydrated with 

 larger quantities of phosphorus pentoxide than were used in the 

 previous case, and was distilled from phosphorus pentoxide. It 

 had a boiling point of 80.2° C. under a pressure of 736 mm. 

 The D. C. was calculated by the formula previously given, and 

 found to be 36.1 at 21° C. 



Propionitrile. — This sample was Schuchardt's preparation. 

 Its boiling point was 94.6° under a pressure of 749 mm. The 

 average of four determinations at different times gave the value 

 26.5 for the D. C. at 22° C. The absorption was slight. 



Butyronitrile. — The sample tested was Schuchardt's prep- 

 aration. It was redistilled from calcium chloride. Its boiling 

 point was 116.5° to 118° C. under 742 mm of pressure. The 

 average of three different determinations is 20.3 at 21° C. 



Iso-propylcyanide. — The sample was Schuchardt's prepara- 

 tion. It was dehydrated with calcium chloride and redistilled. 

 Its boiling point was 106°-107° C. under 744 mm of pressure. 



