TRANSITION RESISTANCE—MACGREGOR. AQ 
ometer gave quite large deflections due only to polarisation of 
the electrodes, and that, however long or however short the time 
during which the alternating currents were allowed to pass 
through the electrolytic cell. 
LENZ,* admitting the error of his assumption, investigated 
the subject again in a different way. Assuming the existence of 
both polarisation and transition resistance in various electrolytic 
combinatiens, he showed by experiment that the latter, if it ex- 
isted at all, must be opposite in its properties to all other kinds 
of resistance. He therefore regarded its existence as unlikely 
and joined with OHM+ and VorssELMAN DE HeEeER} in holding 
that since a transition resistance need not be assumed to account 
for any knewn phenomena, (all phenomena which may have such 
a resistance as their cause being capable of being regarded as 
consequences of polarisation), it may be ignored. 
There is one case, however, in which this transition resist- 
ance is dissociated from polarisation, so that its effects cannot be 
confounded with the effects of polarisation. That is the ease in 
which a current is sent through weak neutral solutions of zinc 
sulphate between electredes ef amalgamated zinc.§ The eleec- 
trodes of such an electrolytic cell are not appreciably polarisable. 
If, then, there is any reduction of the intensity of the current 
produced by the surfaces of the electrodes, it must be due to 
transition resistance, not to polarisation. For the change in the 
resistance of the cell produced by change of its constitution, due 
to electrolysis, can be made so small by using currents of suffici- 
ent!y short duration as net to affect the result. BrEvTz|| has 
alreaiy made use of this combination for the detection of transi- 
tion resistance. His method was that which PoGGENDORF used for 
metals. In two circuits of the same aggregate resistance he pass- 
ed the current across two and across several surfaces of contact 
respectively, and found the measured resistance to be the same. 

*Pogg. Ann. LIX (1843). 
+Schweig. Journ. LXIII, LXIV. See also Fechner’s reply Ibid. LX VII. 
Bull. Sc. phys. nat. Neerland, 1839 (Liv. V), 1840 (Liv. II). 
§Du Bois Reymond, Monatsber. Berl. Akad., 1859 ; Patry, Pogg. Ann, CXXXVI 
(1869). 
|| Pogg. Ann. CXVII (1862). 
