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POPULAR SCIENCE REVIEW. 
toughened glass can he cut through with the diamond, and as, 
moreover its surface can be removed by polishing and cutting 
with the wheel, without injury to the mass, it is evident that it 
must exist under conditions very dissimilar from those of a 
Rupert’s drop. Moreover, melted glass, on being dropped into 
De la Bastie’s bath, gives a similar shaped body, from which the 
tail can be broken off, piece by piece, without injury to the 
body, which can be scratched, knocked and thrown about, with- 
out exhibiting any signs of deterioration. Bearing upon this 
point, too, comes the fact that toughened glass can be elegantly 
engraved, either by Tilghman’s sand-blast process, or by means 
of hydrofluoric acid, in the ordinary way, the surface or outer 
skin being thus removed. 
M. de la Bastie’s Invention marks a distinct era in the history 
of one of our most important industries. Never during the 
history of glass manufacture, which extends over some 3,500 
years, has any radical change been effected in its character. 
The glass-blowers of Egypt, who practised their art before the 
exodus of the children of Israel, and representations of whom 
have been found on monuments as ancient as that event, pro- 
duced a similar glass to that of our own times. This has been 
proved by an examination of glass ornaments which have been 
discovered in tombs as ancient as the days of Moses. It has 
been proved, too, by a large bead of glass, found at Thebes, 
upon which was inscribed the name of a monarch who lived 
1,500 years B.C., and which glass was of the same specific 
gravity as our own crown glass. It is true Pliny mentions that 
a combination was devised in the reign of Tiberius, which pro- 
duced a flexible glass; but both the inventor and apparatus 
were destroyed, in order, it is said, to prevent the value of cop- 
per, silver, and g'old from becoming depreciated. There is, how- 
ever, no evidence whatever that this was the toughening process 
of De la Bastie, nor does the record in any way detract from 
the merits of that gentleman as the inventor of an important 
economic process. The fact remains that the w r orld has now 
given to it for the first time, in a practical form, an invention 
by which the brittleness of glass is superseded by an attribute 
of the most valuable nature — toughness. It is by no means 
improbable that the old adage, 66 as brittle as glass,” will soon 
be superseded by a new one — u as tough as glass.” 
What may be the ultimate result of the introduction of this 
invention in practice it is difficult to foresee, so widespread, so 
universal does its application seem. Not only is it desirable to 
render durable such articles as are at present made from glass, 
but to satisfy a want long felt in every department of art, science, 
and manufacture, of such a material as toughened glass ; and 
this want can now be satisfied. So numerous are the oppor- 
