Gilbert Glass Blowing - Part
NOTE: This book was published in as a manual
to accompany the Gilbert Glassblowing Set as part of the "Boy
Engineering" Series. the exact copyright date is
unknown, although based on information from "The Internet Archive" it is believed
that this publication is in the public domain. Many
today would not consider glassblowing to be a safe activity
for young people. Therefore, this book is
probably best appreciated for its historical value rather than
as a source for current information and good experiments.
If you try anything here, please understand
that you do so at your own risk. See our Terms
Pages 28 - 35
28 BOY ENGINEERING
because the tube tends to cave in on the inside of the bend (2) or
flatten on the outside (3), or both.
Make the bend as follows: Heat a piece of No. 2 tube about 2 inches
from one end in the lamp flame, turn it constantly and move it back
and forth endwise to heat a length of about 2 1/2 inches. When soft,
take the tube out of the flame, and bend the ends upward until the
angle is 90°.
If the bend is flat on the inside or outside, close one end of the
tube in the blowpipe flame, smooth the other end and allow them to
cool, then heat the flat side of the bend in the blowpipe flame and
blow it out slightly.
This makes the diameter of the tube at the bend equal to that of the
remainder of the tube. Cut off the closed end, smooth
the edge, and your bend is complete.
Make bends with No. 4 tube.
Experiment 30. To make a drinking
Many times when there is sickness in the house, it is convenient to
have a glass drinking tube (Fig. 42), through which the patient can
drink without raising his head.
Make such a tube from a piece of No. 4 tubing. The short arm is
equal in length to the depth of the tumbler; the long arm, or
mouthpiece, is about 1 inch longer than this.
Experiment 31. To make a siphon.
Cut off a piece of No 1 tubing 8 inches long, make
two right-angled bends about 1 inch apart at the center, smooth both
ends, and your siphon is complete (Fig. 43).
Experiment 32. Magic.
Put one arm of the siphon in a tumbler of water and suck air out of
the other end. Does the water start running and does it continue to
run in a most magical way (Fig. 44) until the water is below the end
of the siphon in the tumbler?
Fill the tumbler with water again, start the water running, put the
outer arm of the siphon in an empty tumbler, and stand both tumblers
on the table (Fig. 45). Does the water run up one arm of the siphon
the other into the empty tumbler? Does it stop running when the
levels are the same? Stand the first tumbler on a book. Does the
water run again and stop when the levels are again the same (Fig.
Place the lower tumbler on the book and the upper tumbler on the
table. Does the water now run in the opposite direction until the
levels are again the same?
Raise one tumbler a foot or so above the table. Does the water run
up over the edge and drop into the second? Now before the upper
tumbler is empty, lower it in such a way that an arm of the siphon
is in each tumbler, and raise the second
tumbler. Does the water now run in the opposite direction?
You boys who have the Gilbert set on "Hydraulic and Pneumatic
Engineering" will know that it is the pressure of the atmosphere
which causes the water to run up over the edge of the tumbler in
this magical way.
Experiment 33. A long-armed siphon.
Attach a full length of No. 4 tube to each arm of the siphon, as in
Fig. 47, and repeat the experiments described above.
Note: When you insert a glass tube into a rubber coupling or rubber
stopper, wet the end of the glass tube and the inside of the
coupling or stopper, grasp the tube near the end to be inserted, and
insert with a twisting motion.
Experiment 34. To make a nozzle.
Attach a working handle to one end of a piece of No. 2 tube, heat
the tube about one inch from the end in the lamp flame, turn
constantly until soft, tken remove from the flame, and dra>w it
out about 3 inches. When cool, break off the thin tube, cut off the
nozzle to a length of about 2 1/2 inches, smooth the large end, and
your nozzle (Fig. 48) is complete.
Experiment 35. To make a fountain.
Arrange the apparatus as in Fig. 49, and
suck air out of the nozzle. Have you made a beautiful fountain?
Experiment 36. Magic.
Make a nozzle 6 inches long out of No. 2 tube. Smooth the ends of
the nozzle, and long tubes. Arrange the apparatus as in Fig. 50 and
suck air out of the nozzle until the water runs in the siphon. Does
the water squirt out of the nozzle in a magical manner?
Experiment 37. More magic.
Arrange the No. 2 apparatus as in Fig. 51, with the nozzle inside
the bottle. Now to start the apparatus: Fill the bottle about
quarter full of water, insert the tubes in the stopper as shown;
insert the stopper into the mouth of the bottle; invert the bottle;
then put the short tube in a tumbler full of water and the long tube
in an empty pail or basin. Is there a magical fountain inside the
Repeat this with a taller bottle, if you can find one to fit your
two-hole stopper. Do you get a higher fountain?
Experiment 38. Still more magic.
Make another nozzle and attach it to the apparatus used in the last
experiment by means of the inverted siphon (Fig. 52).
Start the experiment as described above. Do you get two fountains?
Experiment 39. To start a siphon.
You can start a siphon without sucking the air out of it as follows:
Fill the siphon with water, put a finger over each end (1, Fig. 53),
place one end in a tumbler full of water and remove the finger under
water (2, Fig. 53), then remove the other finger. Does the siphon
In this case the water you pour into the siphon drives the air out,
and this is the reason you do not need to suck the air out.
Experiment 40. To siphon sand or
Arrange a siphon (Fig. 54), start the water flowing, and then pour
sand or mud into the upper tumbler. Is the sand or mud siphoned over
into the lower tumbler?
Attach a long tube to the outer arm of the siphon and repeat the
experiment. Is the sand or mud siphoned more rapidly and more
Experiment 41. To make a squirt
Make a nozzle at one end of a piece of No. 2 tubing, make a bend
near the nozzle, cut off the other end at such a length that it will
reach to within 1/4 inch of the bottom of the bottle, smooth this
end, allow it to cool; wet the tube and the two-hole stopper, shove
it through one hole of the stopper, insert an elbow in the other
hole, and your squirt bottle is complete (Fig. 55).
Fill the bottle with
water, and blow through the elbow. Do you get a fine long stream
from the nozzle (Fig. 56)?
Experiment 42. To make a trick
You can have any amount of fun with a trick squirt bottle. It is
exactly the same as the squirt bottle described in Experiment 41
except that it has a hole just below the bend (Fig. 57).
To make the hole, make the long bent nozzle as in the last
experiment, then heat the tube just below the bend in the blowpipe
flame, touch a piece of glass tube to the red-hot glass (1, Fig.
58), and pull it away (2, Fig. 58). Do you find that the hot glass
is pulled out into a thin pointed tube? Break off the thin tube
close to the large tube, heat in the blowpipe flame until the
edges are smooth and at the same level as the sides of the large
tube. Flare the edges of the hole, if necessary; it should be about
1/8 inch in diameter.
Now fill the bottle with water, and blow
hard (Fig. 59). Do you find that one stream of water is driven into
your face and another out of the nozzle?
Experiment 43. Fun with a trick
Now to have fun with your trick bottle, show it to one friend at a
time. Do not ask him to try the bottle, just go where he can see you
and squirt a long stream, but unknown to him have your finger over
the hole below the bend. Your friend will just naturally want to
have a try at it. So you say "All right, let's see who can squirt
the longest stream." Tell him that all he has to do is to take a
deep breath and blow as hard as he can. He will do so, with
laughable results (Fig. 60).
Now together find another friend. Do not ask him to blow, but each
of you blow as long a stream as you can, where
"The Science Notebook"
Copyright 2008-2018 - Norman Young