1890.] on dilute solutions of Nitrates and Nitrites. 57 



following, combining them in varying quantities according to 

 the temperature : 



(a) KN0 3 + H 8 = KHO + 2H,0 + NH, , 



08) KN0 3 + H 2 =KN0 2 + H 2 0, 



(a + /3) KN0 2 + H 2 + NH 3 = KHO + NH 4 N0 a 

 NH 4 N0 2 = N 2 + 2H 2 0. 



During the course of this research I received much valuable 

 advice from Mr Sell and Mr Fenton of the University Laboratory 

 for which I wish to acknowledge my obligation. 



In the previous description I have mentioned the fact that 

 the strong solutions of nitrates and nitrites did not produce the 

 same reactions, failing to produce a sufficient quantity of gas. 



Probably this arose from the same kind of difference being 

 produced in the reaction by the variation of the density of the 

 solution, as by the temperature at which it took place. This 

 view was not put to any test. 



(3) On certain Points specially related to Families of Curves. 

 By J. Brill, M.A., St John's College. 



1. The following communication is intended as a sequel to 

 my paper "On the Geometrical Interpretation of the Singular 

 Points of an Equipotential System of Curves*," and in it I pro- 

 pose to show that the theorems which I established with regard 

 to Equipotential Systems are, with certain qualifications, true of 

 a much more extensive class of systems. It is to be understood 

 that the remarks contained in this paper refer to algebraical 

 systems, as it is impossible to reason in a general manner about 

 transcendental curves where imaginary geometry is concerned. 



In my paper entitled " Orthogonal Systems of Curves and of 

 Surfaces f" I showed that if £ and rj be the parameters of two 

 families of curves constituting an orthogonal system, and if h 

 and h 2 be defined by the equations 



S'+®'-v 

 ©"♦©'-v. 



then the value of the expression 



h 2 d^ + iJ^drj 

 dx + idy 



* Proc. C. P. S., vi., pp. 313—320. 

 t Proc. C. P. S., vi., pp. 230—245. 



