Qualitative analysis / by William Briggs and R.W. Stewart.

  • William Briggs
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: Qualitative analysis / by William Briggs and R.W. Stewart. Source: Wellcome Collection.

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    O towards the centre. Then with a file cut the tube at a suitable point, round off the cut ends in the flame, and the jet is ready for use. To make a Bulb-tube.—Take a piece of -^--inch tubing about 6 inches long, and heat one end in the blowpipe flame until it is completely closed and rounded off. Before this rounded end becomes too thick, take it out of the flame, and holding the tube vertical blow into it steadily, but not too strongly, until a small bulb is blown at the heated end. Use of Spatula.—It is often necessary to take a small quantity of some solid substance out of a bottle. For this purpose the spatula—an instrument very like a small table knife—is used. A small bone or ivory paper cutter answers the purpose very well. The blade of a penknife is sometimes used, but the use of iron or steel is objectionable. A platinum spatula is the best to use. To fix a platinum wire in a glass holder.—Take 6 inches of narrow glass tubing and draw it out a little in the middle. Cut in two at the middle of the drawn-out part. Into the narrow cut end insert a piece of platinum wire about 2 inches long; then hold this end in the flame until the glass closes round the wire. A piece of glass rod makes a better holder. Draw the rod out and cut in two as described above. Then hold the narrow end of the rod in the flame until it is quite soft, and insert the piece of platinum wire into the soft end. The platinum wire thus mounted will be in frequent use for flame tests, and should be kept dipping in hydrochloric acid in a test-tube. This can be done by fitting the holder with a cork which fits into the mouth of the test-tube. Kept in this way the wire is always clean. Flame tests.—(1) Place a small quantity of solid sodium carbonate, Na2C03, on a watch-glass. Lift a small portion of it with the loop of the platinum wire, and hold in the lower outer part of the Bunsen flame. The flame shows an intense yellow colour, characteristic of sodium compounds.