The Forest Republican. [volume] (Tionesta, Pa.) 1869-1952, 1884-05-21
A LOST ART UNDISCOVERED.
THE ANc1ENTs' BLACK MIRRORS
MADE FROM FURNACE STAG.
A visit 60 PompeH Results i'm EN-
pcriments which Way RevOiuttOns
ize the Making of GlnSsWnrc,

ize the Making of Glassware.
Pittsburg is the recognized headquar-
ters of glass manufacture in the United
States, and any new discovery relating
to it is always OF interest here. Obsid-
ian, it may be promised is q species OF
volcanic glass, and one of the lost arts
was the manufacture of various articles
! from this material, among them black
mirrors, which are used in the making of
optical astronomical instruments In
the twelfth and thirteenth centuries mir
rors were made from an obsidian stone,
and used principally by the Peruvians.
The first mirror for optical astronomical
purposes was made from obsidian in the
year 1879, by Franciscan monk, Johan-
nus Peckham. who called it Perspective
Communis. He gave the first satisfac-
tory prescription for the manufacture OF
mirrors from this material. That they had
| been known at an earlier day is shown by
| their mention in Pliny's writings. In the
course of time the secret of their manu-
! facture was lost. In the earliest ages
mirrors were made from polished metal.
| Glass mirrors overaid with silver were
used in Europe to some extent in the
thirteenth century, Venice being the seat
| of their manufacture. From Venice the
art went to Bohemia, at that time called
'the mother of glass manufacture" " and
it was not until 1865 that it was con-
veyed to France by one Colbert, a
chemist.
Mr.. Enrico Rosenzi, of this city, who
is entitled to the honor of having redis-
covered the lost art, is a native of Italy,
chemist by profession and practice,
| having studied in one OF the leading
German universities. He is now citi-
zen of Pittsburg, and here conducted
the experiment which ended in his final
success. His attention was first directed
to the subject in 1879, while on visit to
Pompeii. Here he found a fragment of
a statue-an arm-made from obsidian,
and its evident kinship to the lava there
so abundant led him to think it might
have been made therefrom. Bringing
away with him his trophy and quantity
I of lava, he began an investigation and
series of experiments which finally
led him to a knowledge not only
of the component elements of obsidian,
but also as how it might be reproduced
by artificial means. Like all investiga-
tors he met with many obstacles and dis
couragements, all of which only served
to make him persevere more energetically
His first experiments looking toward the
reproduction of the material were made
at Pittsburg glass house, and others in
the furnaces of several of our local steel
works. His first successful melt was
made at the glass factory of George Dun
can & Sons, in the latter part of 1881.
He there made number of ornamental
articles and several slabs of the new
glass, and later went to New York city
and set up a small furnace for its man.
ufacture He one day visited the best
known manufacturer of optical lenses
in the United States, Mr. Weiskopf, and
asked what he would charge for polish
ing slab of it, which he laid before the
great man. Mr. Weiskopf wanted to
know what it was, and when he got the
! information curtly named a high price
J for polishing it. Much to his astonish.
ment Mr. Rosenzi accepted his terms and
, a day was named when the work was tC
? be completed When he called for il
Mr.. Rosenzi was surprised to find al
! of Mr.. Weiskopf's brusquerie gone
= "Do you know what you have
done9" the latter inquired. "You have
= rediscovered the lost art of making blacl
8 mirrors. Don't get excited and thinl
+ there's millions in it for you becaus
: but few of them are used, yet your dis
0 covery is of the greatest scientific i'm
portance" When it came to receivin!
pay for his work he smiled and said
"No, want no money. Just bring m
/ slab like this, or even smaller, and
: will be well paid" He got the slab ant
t from it made mirror which is now Il
T. his possession in New York city. Tn
= first one he made for Mr.. Rosenzi
f now in st. Petersburg whittier it wa
v sent by the consul-general of that coun
try, to whom Mr.. Rosenzi presented il
G The new material has been patentet
: under the name of "ferroline. O
d course the articles entering into its com
e position are the secret of the discoverel
l. but the basic material is furnace Stag
d 1t melts at /, 800 degrees to 1000 dc
b grees F., and can be worked in eightee
II to twenty hours after the materials ar
e placed in the melting pot. Its quail
= tiles are great hardness and strengt
:. far superior to glass, capability {
s being either cast like molten iron {
Y blown or pressed like glass, and suscept
!, bility to the highest possible polish. !
.e is Opaque, the thinnest sheet of it SUI
10 cessfully resisting the passage of light;
d not attacked by any kind of acid, an
=. has clean, highly-polished fracture
If Commercially it is well adapted for tn
1t manufacture of tops for tables an
10 bureaus, slabs or plates for inlaying fu
st niture, marble or wood mantels, fC
d opaque bottles for druggists, fruit ia
le and for wall and other ornaments.
If will take the place of glass in many us
r Ior which the latter is poorly adapte'
al Its cost is some greater than glass, b.
3 not sufficiently so to render its use f
the above purpose too costly. Mr.. r
SEMI has not yet entered upon its man
h. facture except on an experimental seal