APPARATUS for MAKING and ALKALINE EARTH METALS J. F. BIRMINGHAM, JR., AND W. H. WOOD Chandler Laboratories, Columbia University, New York City
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T IS often necessary to produce colors characteristic of Li, Na, K, Ca, Ba, and Sr compounds for classroom and laboratory purposes. The difficulty usually encountered is that the colors do not last, and they require constant attention when used for periods of one hour or more. The simplest method of production is to form a bead of some salt of the metal upon a platinum wire, and hold i t in the non-luminous flame of a burner. The bead must consist of some material that melts easilv. and yet does not vaporize too rapidly a t the tempera: ture of a Meker flame. The chlorides of calcium, barium, and strontium melt easily and hydrolyze to highly refractive oxides a t higher temperatures. The beads of these salts produce brilliantly colored flames. On the other hand, t h e salts of lithi;m, sodium, and potassium are quite volatile, and except for sodium salts, minute traces of which give good colors, the beads give flames that are brilliant, but do not last more than several minutes. Flames larger and more intense than those obtainable from salt beads may be produced by means of the atomizer outfit described below. It is very simple to construct and, once set in operation, requires no further attention for several hours. The apparatus consists of a 250-cc. Erlenmeyer flask (Figure I), fitted with a two-hole rubber stopper. glass holds This tubingthe bent nozzle, a t right whichangles is made 6 to of 8ordinary cm. from 6-mm. one
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AjJ nozzle
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end, and bent and drawn out to a tip a t the other. It is FIGURE l.-A~oaarz~x Ouran made so that the latter bend rests on the bottom of the flask, with the tip 1 to 2 cm. from the side of the flask and perpendicular to it. Since the wall of an The burner is a standard microburner which was ordinaty pyrex Erlenmeyer makes an angle of 70' with chosen because the air vent was in the base, making it a the base, the bend near the tip should be approximately simple matter to introduce the salt spray. The flame 70' from the vertical. This is made clearer by the is non-adjustable, non-luminous, 10 to 14 cm. high, and diagram. The inside diameter of the tip should not be the air stream from a 1-mm. nozzle cannot blow i t out. much more than 1mm. This burner has the added advantage of being small With 100 CC. of salt solution-2 molar-in the flask, and light, and when mounted above the flask, renders and with an air supply connected to the nozzle, a the whole atomizer unit compact. rapid stream of fine bubbles issues from the tip and is A battery of six such units has been in use for general further subdivided by striking the side of the flask. chemistry courses a t this university for the last feu Consequently, a very fine spray is produced which is en- semesters. Figure 2 is a photograph of this outfit. trained in the current of air and passes out of the flask The air inlet tubes are connected to other tubes which through a straight glass tube, T,and the air vent, V ,of a pass through the back-board and are held .by small burner, causing the spectral flame characteristic of rubber stoppers; the outlet tubes of two atomizers are the metal whose salt solution is contained in the connected to an inverted Y-tube, the upper end of which flask. is placed inside the air vent of a microburner. Thus 240
only three burners are required, all fed from the same gas line by a glass tube with three outlets. The air supply is connected with any one of the flasks and the color will be maintained as long as required. The spectral lines of the metals may be conveniently
viewed by means of a small pocket spectroscope. This instrument has the advantage of permitting one to see all the lines, from violet to red, a t once. When the class is large and i t is desired to show each member individually the spectral lines, some device for making rapid changes from one solution to another is of value. A six-way valve in the air line may be added to the apparatus, but it is expensive. At the suggestion of Mr. J. 0.Percival, the adaptor shown in Figure 3 has been used in our outfit. A one-inch brass rod was drilled through the center and turned on a lathe so that a No. 2 rubber stopper fitted closely inside. This adaptor was connected to the air supply and No. 2 stoppers were-put on the ends bf the air inlet tubes in the back. Rapid changes may now be made merelv bv shiftinr the adaptor from one inlet to anFIGU~S.-ADA~ORI~OR other. No. 2 RUBBER STOPPER A
FIGURE 2.-BATTERY OF SIX ATOMIZERUNITS SALTSOR Na, K. Li, Ca, Ba, Sr
