Inserting Glass Tubing into Stoppers

After fire-polishing a glass tube, let it cool before trying to place it in a stopper. Do not try to speed up the cooling process by placing the tube under running water, because the rapid temperature change is likely to cause a crack on the newly prepared end. 

5 Removing Glass from Stoppers and Flexible Tubing 

---

F. Inserting Glass Tubing into Rubber stoppers... 

FIGURE F.l. Inserting glass tubing into a rubber stopper. 

Glass cuts can be minimized by use of correct procedures (for example, that for inserting glass tubing into rubber stoppers and tubing, which is taught in introductory laboratories), through appropriate use of protective equipment, and by careful attention to manipulation. 

Insert the rubber stopper with the glass tubing into the flask. 

Inserting glass tubing, rods, or thermometers into stoppers is very hazardous and the following... 

Insert a medicine dropper (or short glass tube) into a 0 1-hole rubber stopper (b) if you are using a measuring tube in FIGURE 12.1 or into a 00 1-hole rubber stopper if you are using a buret in FIGURE 12.1. 

Dissolve 180 g. of commercial ammonium carbonate in 150 ml. of warm water (40-50°) in a 700 ml. flask. Cool to room temperature and add 200 ml. of concentrated ammonia solution (sp. gr. 0 88). Introduce slowly, with swirling of the contents of the flask, a solution of 50 g. of chloroacetic acid (Section 111,125) in 50 ml. of water [CAUTION do not allow chloroacetic acid to come into contact with the skin as unpleasant burns will result]. Close the flask with a solid rubber stopper and fix a thin copper wire to hold the stopper in place do not moisten the portion of the stopper in contact with the glass as this lubrication will cause the stopper to slide out of the flask. Allow the flask to stand for 24-48 hours at room temperature. Transfer the mixture to a distilling flask and distil in a closed apparatus until the volume is reduced to 100-110 ml. A convenient arrangement is to insert a drawn-out capillary tube into the flask, attach a Liebig s condenser, the lower end of which fits into a filter flask (compare Fig.//, 1) and connect the... 

Procedure B (carbonate-free sodium hydroxide). Dissolve 50 g of sodium hydroxide in 50 mL of distilled water in a Pyrex flask, transfer to a 75 mL test-tube of Pyrex glass, and insert a well-fitting stopper covered with tin foil. Allow it to stand in a vertical position until the supernatant liquid is clear. For a 0.1 M sodium hydroxide solution carefully withdraw, using a pipette fitted with a filling device, 6.5 mL of the concentrated clear solution into a 1 L bottle or flask, and dilute quickly with 1 L of recently boiled-out water. 

Two sets of stoppers are very useful, one set unbored and a second set with a single hole bored in them to carry blowing-tube connectors. A longer piece of glass tubing inserted into the hole will also form a very adequate handle when working small pieces of apparatus. 

---