50 
THE YOUNG SCIENTIST. 
A Cheap Audiphone. 
Ed. Young Scientist— For the small sum of 
ten cents, I can make what I call on " audifan," 
that will give as good satisfaction as any audi- 
phone invented. I take a common Japanese 
fan, one with reed handle and braces entire, cut 
off al)out one half inch from the top edge, adjust 
thereto a small strip of tin, binding four or five 
inches in length and one quarter inch in width 
when doubled, and clinch the same for a moutli- 
piece. I then give the whole fan one coat of 
shellac and lamp-black, using enough black to 
overcome in part the gloss of the shellac. If 
one end of a small strip of curved brass wire be 
inserted just over the string that gives tension 
to the curved wooden brace, so as to rest 
against it, and the other end is clinched between 
the edges of the metal binding, the fan will as- 
sume the proper position and always be ready 
for use. The fan should be painted and allowed 
to dry thoroughly before the curved brass is 
adjusted. The fan can be used without the 
brass brace, if a narrow strip of silk be pasted 
down the centre of the fan to protect the paj^er. 
L. B. De Veau, New York. 
Paste Eels. 
Ed. Young Scientist— The paste came safely to 
hand, and by following your directions, I soon 
had a large supply, enough for all my friends, 
but, although it was easy to see the eels by 
transmitted light, I found it very difficult to get 
good I'esults with black-ground illumination, be- 
cause the paste with which they were mixed re- 
flected the light in all directions, and the effect 
Avas entirely destroyed. The question then was, 
how to get the eels free from the paste in which 
they lived ? The following simple manner of 
solving this problem may be of interest to your 
readers. 
I placed some paste (about a tablespoonful) in 
the bottom of a tea-cup, and placed it in a warm 
place. The eels bred and grew rapidly, so that 
in forty-eight hours it was a seething mass of 
life. At the same time the paste dried up and 
became firm. As soon as the paste was so solid 
that it would not readily mix with water, I 
placed a piece of stiff paper, about three-quar- 
ters of an inch in diameter, on its surface, and 
on this paper I poured about half a teaspoonful 
of water. The object of the paper was to pre- 
vent the stream of water from disturbing the 
paste. After the water had stood about half a 
minute to a minute on the paste, I removed a 
drop by means of a dipping tube, and deposited 
it on a clean slide. It was full of eels, and almost 
quite free from paste, so that when illuminated 
by very oblique rays, the little animals ap- 
peared like luminous serpents moving about in 
a dark sea. When the paste is allowed to be- 
come partially dry, and water is laid gently on 
its surface, the eels pass at once from the paste 
to the water and the latter is literally filled 
with them. 
Annealing Steel in Boiling^ Water. 
Amateuk mechanics who work steel either in 
the vice or the lathe, are often annoyed by the 
difficulty of softening certain pieces. Some 
specimens of steel, when heated to a low red > 
heat and slowly cooled in ashes, become quite ?i 
soft ; other pieces wholly resist this treatment, j 
and although they can be cut and filed, they do h 
not come to that fine softness, which makes a 1 
piece of well-annealed steel so pleasant to work. 
Other pieces again become " pinney," as it is j 
called, that is, full of spots which are quite 
hard, while the rest of the metal is quite soft. 
The observations of Prof. W. Mattieu Williams 
will prove interesting to those who have been 
troubled in this way. He says : " I will narrate 
some curious experiments that I commenced 
when in Sheffield, but have not satisfactorily 
completed. They were made at the suggestiop 
of Mr. William Bragge, then a managing direc- 
tor of Sir John Brown's works. He had learned 
that the steel wire strings of piano-fortes are 
annealed by what appears a very anomalous 
process— viz., by making the wire red-hot and 
then plunging it into boiling water. Ordinary 
experience would suggest that this must 
harden the steel in some degree, but I tried it 
upon many samples of steel— mild Bessemer 
steel, sheer steel of different qualities, and the 
hardest oid-fashioned Sheffield ' pot-steel '—and 
found that in every case, when the operation 
was properly performed, the steel was remark- 
ably annealed. I compared samples cut from 
the same bar— one heated and slowly cooled by 
burying in ashes under a furnace grate, the 
other by immersion in boiling water— and found 
that when subjected to bending tests those 
which had been cooled in the boiling water 
would bear a more severe degree of flexure 
without cracking than the pieces which had 
been more slowly cooled in the ashes. They 
were not so soft, as tested by the touch of the 
flle, but unquestionably tougher and more re^ 
liable when subjected while cold to violent bend-' 
ing blows of a hammer. It was more effectual 
than any device of 'oil toughening' or slow 
cooling I have had opportunities of testing. 
Certain precautions are necessary. In the first 
place, the water should be quite at the boiling 
