BEFORE COMPLETION OF THE VOLTAIC CIRCUIT. 
187 
19. Those who had the pleasure of witnessing the experiments of Professor Da- 
niell, at King’s College, when a series of only seventy pairs of his constant battery 
was used, will no doubt recollect the brilliant effects produced with this powerful 
apparatus, and may form some idea of those obtained by using nearly one third 
increase of power. Titanium, which had been previously given to me by Dr. Faraday, 
was fused into a solid mass, and is now in that gentleman’s possession ; platinum was 
volatilized ; and the flame from charcoal as well as from metallic electrodes was so 
intense as to render it indispensable that the eyes of those present should be protected 
by thick screens of black crape. On another evening sixteen feet four inches of pla- 
tinum wire No. 20 iron gauge, was ignited to a red heat; and even this length might 
have apparently been extended had I had a greater quantity of that wire ; but with 
such a powerful apparatus no effect could be obtained even through one thickness 
of a silk handkerchief. 
20. It will be seen by the preceding experiments that I was unsuccessful in my 
attempts to obtain a direct spark, or what is usually denominated the striking distance, 
by the direct or unassisted action of any of the powerful batteries hitherto described 
in this paper ; but that when a Leyden battery of nine jars was introduced in the 
circuit of the 1024 series (15. 16.), the spark passed through the space of ^ths of 
an inch. 
It is necessary to explain, that, since making the experiments I am about to describe, 
my attention has been pointed to similar results obtained by Dr. Faraday in his Ninth 
Series*; and had I been aware of them I should certainly have saved myself much 
useless time and expense. The results are however in every way confirmatory of the 
experiment of this philosopher'!'; but from the powerful apparatus I used the results 
obtained were proportionately more decided. 
21. In the course of my previous experiments I had often introduced coils of copper 
ribbon and of copper wire in the circuit of the voltaic battery, without being enabled 
to obtain any indication of a spark before contact, although the brilliancy of the spark 
is thereby so much increased when the contact is broken. From the effects obtained 
by the water battery (15. 16.) of 1024 series, when the Leyden battery was introduced 
in the circuit, I was induced to try what effects could be obtained by what is generally 
called the secondary coil, or the action of an induced current. It is not, however, 
my intention to enter into the particulars of the numerous experiments made by 
myself, in conjunction with those private friends who kindly assisted me in this in- 
quiry, but I will at once briefly explain the apparatus I ultimately used, and from 
which the most satisfactory results were obtained. 
22. Twelve hundred and twenty-five iron wires, No. 20 gauge, each wire about 
twenty-one inches long, being previously well coated with resin, were bent into the 
usual horse-shoe form. 115 feet of No. 12 copper wire, well covered with cotton, 
and divided into three separate lengths, were then wound round the iron wires ; bind- 
* Philosophical Transactions, 1834. f Ninth Series. § 1090. 
2 B 2 
