66 
THE YOUNG SCIENTIST. 
the clothing, or the furniture, and which 
are so easily performed that any boy or 
girl who has a taste for such things need 
fear no risk of failure. 
All the experiments which we shall de- 
scribe may be performed by means of 
such ordinary articles as may be found in 
every household, with the exception of a 
few pieces, which may be made by any 
village carpenter or blacksmith, or may 
be bought for a few cents. We shall give 
most minute directions for making every 
piece of apparatus that is used, well- 
knowing that an experiment which is per- 
formed by means of things which we our- 
selves have got up is far more interesting 
than those of much greater brilliancy and 
beauty, which are performed by means of 
apparatus that has been purchased. 
One of the most striking circumstances 
connected with chemical action is the 
change which it x:>roduces in the condition 
of bodies. Thus a bar of solid iron, which 
seems to the ordinary mind one of the 
most substantial of objects, may be dis- 
solved and rendered not only quite invisi- 
ble, but imperceptible to the touch. The 
same is true of a mass of lead or silver, 
and the following experiments Avhich 
illustrate this are at once simple and 
striking. 
TO CHANGE A PIECE OF STEEL TO COPPER. 
Take a strong solution of sulphate of 
copi)er, or blue vitrol, as it was called 
in olden times, and dip into it a piece 
of clean and bright iron or steel, such 
as the blade of a knife. If the sur- 
face of the metal is perfectly clean, and, 
in particular, free from grease, it will, in 
a few minutes, be changed to copper. We 
use the word " changed '* advisedly, for 
the iron is actually dissolved and the cop- 
per takes its place. 
A somewhat striking modification of 
this experiment may be performed as fol- 
lows : Have a flat piece of polished iron, 
such as a knife blade, perfectly free from 
grease, and a sponge or wad of rags 
soaked in a strong solution of sulphate of 
copper, to which a very little tartaric acid 
has been added. On rubbing the iron with 
the sponge it will be instantly changed to 
copper. 
Song of the Frog. 
BY MARY H. WHEELEK. 
Brothers, brothers in the mire, 
Long-tailed tadpoles, frogs entire. 
Come up from the mud below ! i 
Hark, again the waters flow! 
Hibernating days are o'er. 
We may swim and sing once more. 
Brothers, brothers, hear my call! 
Come up quickly, one and all ! 
On the banks of pools o'erflowing, 
Green, oh ! green the reeds are growing". 
And the zoospores, set free, 
Whirl around and round in glee. 
Brothers, lo ! the days are long, 
Time it is to raise our song! 
Twilight, ling'ring in the bogs, 
Listens for the voice of frogs. 
Shall fair Spring commence her reign. 
Unannounced by our refrain ? 
Brothers, of Batraehian race, 
From great sires our blood we trace ! 
But alas ! for glory gone 
With the labyrinthodon! 
Ah ! Ids singing was no joke, ^ 
Now we only croak and croak. 
Brothers, brothers, our hearts still ' 
Feel the great ancestral thrill ! 
This is why in our veins flow 
Blood discs of such size, you know. 
But the fugue we sing so late, ' 
Is for race degenerate. 
Pittsfield, N. H., April, 1881. 
Polishing Vulcanized Rubber. 
Kemove scratches with a smooth, wet water- 
of- Ayr stone, and then polish in the lathe with 
fine pumice and a stiff brush. After washing- 
the pumice off, polish it with whiting and soft 
brush. The mathematical instrument makers- 
treat it as brass ; that is, for flat work they use 
water-of-Ayr stone, and then rottenstone and 
oil. Turned work is polished in the lathe with 
rottenstone and oil, taking care not to use too 
high a speed, which would heat tlie work. Some 
use lampblack and oil to finish with where a very 
high polish is wanted, or the bare palm of the 
hand, as in getting up silver plate. Chain and 
ornament makers use circular buffs for their flat 
work, made out of sea-horse leather, and for 
work of irregular forms, buffs of calico. A. 
number of pieces, 12 inches in diameter, are- 
j screwed together between flanges, like a cir- 
cular saw spindle, and used wih rottenstone,, 
! always taking care not to heat the work; 
brushes are not at all suitable for it. 
