Year: 1874

The cracking of q picture placed in
the sunshine set Van Dyck to expert.
menting to produce varnish that would
dry in the shade. He found what he
sought, and found besides that by mix
ing it with his colors they acquired
greater force and brilliancy, and re-
quired no subsequent vanishing, and
so came about the discovery, or re-dis-
covery, of the art of painting in oil.
Mezzotint owes its invention by Prince
Rupert to the simple accident of sem
try's gun barrel being rusted by the
dew. Henry Scanward, Nuremburg
glass cutter, happened to let some aqua
FORTS fall upon spectacles, and noticed
that the glass was corroded and softened
where the aquafortis had touched it.
Taking the hint, he made the liquid ac-
cordingly, drew some figures upon q
piece of glass, covered them with var
nish, and applied his corroding fluid,
which cut the glass around his drawing,
so that when he removed the varnish
the figure appeared raised upon dark
ground; and etching upon glass was
added to the ornamental arts. Alois
Senefclder, playwright and actor, think
ing it possible to etch upon stone in
stead of copper, polished q slab for the
purpose. He was disturbed by his
mother coming into his small laboratory
with request that he would jot down
her list of things for wash, as the
woman was waiting to take the bas-
ket away. And as there was no paper
nor ink handy, Senefelder scribbled the
items on the stone with his etching pre-
paration, that he might copy them at
leasrre. Some time afterward, when
about to clean his stone, he thought he
might as we'll see what would be the eff
feet of biting the stone with aquafortis,
and in few minutes saw the writing
standing out in relief. Taking up a
pelt ball charged with printing ink, he
linked the stone, took off few impress
sions upon paper, and he had invented
lithoSraphy. The pelt ball used by
Senetelder was long indispensable in q
printing office. A Salopian printer in
hurry to get on with a job, could not
find his ball, and linked his form with a
piece of soft glue that had fallen out of
the glue-pot; with such excellent re-
suits that he henceforth discarded the
pelt ball altogether, and, by adding
treacle to the glue, to keep it from
hardening, hit upon the composition
of which printers rollers have ever
since been made. Three very different
discoveries are recorded to have resulted
from the unintentional application of
intense heat. Pliny attributes the dis
covery of glass to some merchants,
travelling with inter, who stopping on
the banks of river to make meal
were at loss for stones to set their
kettles upon. Putting them upon
pieces of inter, they kindled their fires;
the inter, dissolved by the heat, mixed
with the sand, and the merchants we're
astonished to see transparent matter
flowing over the ground, which was
nothing else but glass. Charles Good
year had for many years experimental
in vain, hoping to deprive india-rubber
of its susceptibility to the action of heat
and cold. Conversing with a friend
upon the subject, he emphasized an as
sertion by f1inging piece of sulphured
rubber across the room. 1t lighted
upon the stove; and when he picked it
up he found that the intense heat TO
which it had been subjected had con-
ferred upon the india-rubber just ex-
aotly the quality he had so long been
striving to impart to it. According to
some, he stumbled upon the discovery
in different manner; but, at any rate,
vulcanized india-rubber was the creation
of accident. A Limerick tobacconist,
looking dolefully at his poor neighbors
cropping among the smouldering ruins
of his burned-out shop, noticed that
some OF them, after trying the contents
OF certain cannisters, carefully loaded
their waistcoat pockets from them. He
followed suit, and found that the snuff
had come out of the fiery ordeal very
much improved in pungency and aroma.
Like a wise man he said nothing, but
took another place, set up lot of ov-
ems, and before long Black Yard snuff
otherwise Irish Blackguard"-w
all the rage with the lovers of nasal
titillation; and in few years Lundy-
foot was rich man, owing to the acci-
dent he thought had ruined him. A
would be alchemist, seeking to discover
what mixture of earths would make the
strongest crucibles, one day found he
had made porcelain. Instead of trans
muting metals as he had fondly hoped
to do, Bottger transmitted himself; as
if he had been touched with coniur-
er's wand, he was on sudden trans
formed from an alchemist into potter.
Chambers Journal.





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