1854.] OF THE ROYAL INSTITUTION. 355 
The character of the phenomena described in this report, induces 
me torefer to the terms intensity and quantity as applied to electricity ; 
terms which I have had such frequent occasion to employ. These 
terms, or equivalents for them, cannot be dispensed with by those who 
study both the static and the dynamic relations of electricity ; every 
current where there is resistance has the static element and induction 
involved in it, whilst every case of insulation has more or less of the 
dynamic element and conduction; and we have seen that with the 
same voltaic source, the same current in the same length of the same 
wire, gives a different result as the intensity is made to vary, with 
variations of the induction around the wire. The idea of intensity 
or the power of overcoming resistance, is as necessary to that of elec- 
tricity, either static or current, as the idea of pressure is to steam in 
a boiler, or to air passing through apertures or tubes: and being 
independent of the idea of quantity, we must have language com- 
petent to express both relations. Furthermore, I have never found 
either of these terms lead to any mistakes regarding electrical action, 
or give rise to any false view of the character of electricity or its 
unity. I cannot find other terms of equally useful significance with 
these; or any which, conveying the same ideas, are not liable to 
such misuse as these may be subject to. It would be affectation, 
therefore, in me, to search about for other words ; and besides that, 
the present subject has shewn me more than ever their great value 
and peculiar advantage in electrical language. 
[M. Farapay.] 
The fuze referred to in page 347, is of the following nature. 
Some copper wire was covered with sulphuretted gutta percha ; after 
some months it was found that a film of sulphuret of copper was 
formed between the metal and the envelope; and further, that when 
half the gutta percha was cut away in any place, and then the copper 
wire removed for about } of an inch, so as to remain connected only 
by the film of sulphuret adhering to the remaining gutta percha, an 
intensity battery could cause this sulphuret to enter into vivid igni- 
tion, and fire gunpowder with the utmost ease. The experiment was 
shewn in the Lecture-room, of firing gunpowder at the end of eight 
miles of single wire. Mr. Faraday reported that he had seen it fired 
through 100 miles of covered wire immersed in the canal, by the use 
of this fuze. 
