1822.] Mr. Deuchar on the Ductility of Glass. 359 
glass, so far as my information goes, has thrown out any hint on 
the subject ; on which account I have been induced to lay the 
present facts before the Society; it would be tedious and 
unnecessary to occupy the time of the Society in giving an 
account of the whole of the numerous experiments in which I 
have been engaged. J shall, therefore, select a few of the more 
striking. 
Exper. 1.—Some of the hollow glass threads were put into 
distilled water, and then placed under the receiver of an air- 
pump ; upon the air being withdrawn from the receiver, bubbles 
of air issued from the ends of the glass threads, and continued 
to do so as long as the exhaustion was kept up.* 
Exper. 2.—!n another experiment, 20 grains of glass thread, 
drawn from a tube, fig. 6, were kept at the bottom of ajar of 
Fig. 1. Fig. 2. Fig. 3. Fig. 4. 
ate 
Fig. 5. Fig. 6. Fig. 7. 
mercury, under the receiver of an air-pump, and the air was 
withdrawn; the glass was weighed after the experiment, and 
found to have increased to more than twice its former weight 
from the mercury which then cccupied the space from which 
the air had escaped. The hollow threads are more brittle than 
the solid. 
Exper. 3.—Another experiment may be selected which shows 
the result in a more striking point of view ; a piece of a thermo- 
meter tube, the bore of which was very small, was drawn into 
threads remarkably fine. The wheel, round which the threads 
were spun, had a circumference of three feet, and this, making 
500 revolutions in a minute, proved that 30,000 yards of the 
glass had been drawn round it in an hour; and as the state of 
fusion and quantity fused at a time of the glass is the same, 
whether the drawing be rapid or slow, it follows that in this 
example the thread must have been very fine, and its bore 
‘almost incalculably minute. Some of this thread was cut into 
pieces an inch and a half long, and these so situated on the top 
* These experiments were performed in the presence of the Society. 
