398 



ON THE ELECTRIC CONDUCTIVITY OF NITRIC ACID. 



TABLE XI. 



From these figures it will be observed that the minima values for alO 4 and 

 maxima for /SlO 6 occur in the cases of 3*07, 1'84, '99, and '55 molecular proportions 

 of water, or very approximately HNO 3 .3H 2 0, HNO 3 .2H 2 0, HN0 3 .H 2 0, and 

 2HN0 3 .H 2 O, and the curve representing the conductivity units in terms of per- 

 centages is markedly discontinuous at points corresponding to the three last hydrates, 

 the existence of which has also been confirmed by a series of experimental determi- 

 nations of the densities and contractions of samples of acid of various concentrations. 

 Further evidence is thus added by an independent method to that already accumu- 

 lated as to the existence of definite combinations of nitric acid with water. 



In conclusion, we trust that these observations may serve as an addition to our 

 knowledge of the electric and chemical properties of dilute, and especially of the 

 most concentrated nitric acid, purified, as we hope, with such methods as are 

 available in the present state of chemical art. It appears that for this and similar 

 investigations a material, which should at once be perfect in its transparency, its 

 non-conductivity, and its unalterability by the strongest reagents, remains still an 

 ideal. 



