118 Mr. 0. Heaviside on the 



Phosphoric acid closely resembles dichloracetic acid ; only 

 in very dilute solutions does it surpass that acid. Citric acid 

 corresponds with malonic acid in behaviour on dilution ; it 

 forms no salts with alkaline reaction, but is much weaker than 

 phosphoric acid. Strong tribasic acids have not yet been 

 examined ; but their behaviour may be deduced from the 

 results already obtained. 



The results for dibasic and tribasic acids cannot be brought 

 into mathematical form until a rational expression is found 

 for the law of dilution of the monobasic acids. It is evident 

 that the dibasic acids must be regarded as to some extent the 

 sums of two monobasic acids having different conductivities. 

 The prospect presents itself of finding numerical expressions 

 for the function of the replaceable hydrogen of the polybasic 

 acids. 



XIY. On the Self-induction of Wires. 

 By Oliver Heaviside*. 



A SERIES of experiments made some years ago, in which 

 I used the Wheatstone-bridge and the differential tele- 

 phone as balances of induction as well as of resistance, led me to 

 undertake a theoretical investigation of the phenomena occur- 

 ring when conducting-cores are placed in long solenoidal coils, 

 in which impressed electromotive force is made to act, in 

 order to explain the disturbances of balance which are pro- 

 duced by the dissipation of energy in the cores. The simpler 

 portions of this investigation, leaving out those of greater 

 mathematical difficulty and less practical interest, relating to 

 hollow cores and the effect of allowing dielectric displacement, 

 were published in the ' Electrician ' from May 3, 1884, to 

 January 3, 1885. 



This investigation led me to the mathematically similar 

 investigation of the transmission of current into wires. I say 

 into wires, instead of through wires, because the current is 

 really transmitted by diffusion from the boundary into a wire 

 from the external dielectric, under all ordinarily occurring 

 circumstances. In the case of a core placed in a coil ihe 

 magnetic force is longitudinal and the current circular ; in 

 the case of a straight round wire the current is longitudinal 

 and the magnetic force circular. • The transmission of the lon- 

 gitudinal current into the wire takes place, however, exactly 

 in the same manner as the transmission of the longitudinal 

 magnetic force into the core within the coil, when the boun- 



* Communicated by the Author. 



