Ae) Rt ee oe 
— > 
owe 
- 
er 
a> 4 - 
we eal 
— on 
7) 
and the Magnetism of Violet Light. 269 
of platinum, while the silver yields a bright light, sufficiently 
intense to read ly. The diameter of the wires employed is 
1-100th, and that of the ring about 1-4th ofaninch. The wick 
of the spirit-lamp is spread out and flattened, and the spiral con- 
taning say twelve rings is supported upright by a pin. The 
lainp is then ignited, and carefully extinguished by the momen- 
tary application of the cap. The light emanating from the silver 
is more beautiful than that from platinum; and moreover, the 
experiment is less difficultly performed. 
I beg to add, that | have succeeded in obtaining aphlogistic 
’ phenomena by using silver wire and camphor. For this purpose 
I use a slice of camphor a little larger than the diameter of the 
wire cylinder. The metal is then fixed by a pin passing through 
the camphor into a bit of cork, so that the pin may not fall when 
the camphor fuses. By this light I could distinctly see 4o read 
a letter. f 
In every experiment it is necessary to have the wire incandes- 
cent prior to extinction of the flame, which in consequence of 
the hollowness of flame (already pointed out in one of my former 
papers) can only be obtained when the wires come in contact with 
the outer fringe of the cone. 
There is another very interesting discovery on which I have 
expressed a degree of surprise, since amply removed. I advert 
to the communication of magnetic powers toa steel bar by vio- 
let light, announced by Dr. Morrichini of Rome. On my return 
from Naples, I had the pleasure of seeing the Professor. He has 
succeeded in magnetizing no Jess than seventy-four steel bars, 
and was so good as to present me with one so treated. It is at- 
tractive of iron filings, and possesses a high polarity. The fol- 
lowing is recorded on the wrapper, descriptive of the circum- 
stances which accompanied the experiment. — “ Adi 1 7bre 
1512. Num. 3, Essendo il tempo nuvolo ed umido non é seguita 
Yesperienza, anzi l’ago perdette quella piccola virtt: magnetica 
che avea acquistata il giorno precedente, Avendolo posto alle 
solite prove il giorno dopo, si é calamitato al solito.”’ 
It is by no means necessary (as Professor Playfair has stated) 
that the needle rest in the magnetic plane; for Professor Morri- 
chini assured me that he had succeeded with the needle in various 
positions on the horizontal level, and even vertical and more or 
Jess inclined. The bright solar beam admitted by a convenient 
aperture is received by the prism. ‘The prism is then turned 
upon its axis so as to insulate the violet light, and the ray is then 
projected on the needle by means of a Jens possessing conside- 
rable convexity, and about three inches diameter. For the rest 
_ L beg to give you a few abridged extracts from Professor Morri- 
chini’s memoir, entitled “Secondo Memoria sopra la forza mag- 
netizante 
