860 Mr. Deuchar on the Ductility of Glass. [Nov. 
of the receiver of an air-pump, that the one end of each tube 
communicated with the interior, and the other with the exterior 
of the receiver; to make the result still more satisfactory, a few 
of the threads had their under ends bent out from the rest; 
mercury was then poured over the upper ends of the glass 
threads, and the air thereafter exhausted from the receiver; upon 
which being done, the mercury was seen entering the receiver 
through the minute tubes, and falling in drops from them. 
The effect of this minute ductility was next tried with regard 
to glass rods of different shapes, which led to very curious 
results ; specimens of which I beg now to lay before the Society, 
and to the most particular of these I shall take the hberty of 
directing their attention. 
1. The specimen marked A was drawn from a narrow piece of 
window glass, cut with a diamond, and of course presenting 
very sharp angles; shown in figs. 1 and 4. This thread, when 
examined with a powerful microscope, was found to present a 
flatted oblong appearance with four well marked right angles, 
fig. 1. It is very likely that this peculiar shape is the cause of 
the superior lustre of the specimens of thread drawn from win- 
dow glass; the round crystal rod always gives a dull appear- 
ance, and the lustre brightens as the specimens assume more an 
angular form. Fig. 7 is a square piece of crystal, the threads 
square. 
2. The specimen marked B was drawn from a twisted piece 
of square glass, fig. 9. When examined with the glass, the 
thread was found to be square, but had lost the twisted appear- 
ance of the original. 
3. The specimen marked C was drawn from a piece of fluted 
crystal, presenting four grooves, figs. 2 and 3, The fluted 
appearance is most distinctly retained by the spun glass, when 
placed before the microscope, fig. 2. 
4, The specimen marked D was drawn from a twisted piece 
of grooved glass, see fig. 5. The threads retain the same form, 
but from the number of the grooves, a powerful glass is required 
to examine it. The spun glass appears to have thé grooves 
straight. 
From these examples, and from more than 50 others which 
have been tried, it is proved that glass has the singular property 
of retaining the shape, although brought to the fluid state, and 
although drawn into threads at that high temperature; and if 
the external form remain unchanged, we are entitled to conclude, 
‘that the internal form and arrangement will follow the same law. 
Some experiments were next tried by combining glass of 
different colours into one rod, and then spinning it out into 
_threads as before, tig. 8. The thread was always found to retain 
‘all the colours of the original red unchanged, and did not pre- 
sent the smallest appearance of a break off in any of the coicurs, 
or of the slightest intermixture; sometimes 2, 3, nd even 10 
