To speak frankly we were disappointed in the caliber of the entries submitted in the fifth contest.' Every contribution without exception left something to be desired and many of the accompanying drawings were poorly drafted, or incorrect, or both. After much tearful consideration we have selected the contribution of Robert C. Schmitz, of Milwaukee, Wisconsin, as sufferingfrom the least of many evils, even though he did not elect to correct the entire picture in his drawing. We shall not, however, quote his criticism in full. To dissolve sodium chloride quickly, the salt should'be placed directly in the water and stirred. The test tube with a small hole in it, that was shown suspended in the water, prevents the salt from dissolving rapidly. . . . The Hoffmann electrolytic apparatus, as was shown in the drawing, was insufficiently supported. The a p p a r a t u s should be held by a clamp on each of the two collecting chambers, instead of one clamp on the reservoir tube. If supported with one clamp, as is shown in the drawing, a slight jolt would break the tube, and also if one should draw off some of the gas that is heing liberated, and the stopcock offered a little resistance, the tube might he broken. The drawing did not show the small passageways in the cores of the stopcocks, but it did show the handles of the cocks parallel with the tubes; for these reasons one concludes that the cocks are open, thereby permitting the gases t o escapeinto theatmosphere. The clamp of the stand, as was shown in the drawing, blocked the passageway of the water in the reservoir tube, the mouth of this tube was also shown closed. The arm of the clamp was drawn through the collecting chamber containing oxygen, and i t likewise had shown the passageways of the gases closed, thus preventing either of the gases from heing drawn off. The wires leading to the platinum electrodes, as were shown in the drawing, had no protective glass insulation to give them a rigid support or t o keep them from being bent.
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See THISJOURNAL, 7,436-7 (Feb., 1930). 895
JOURNAL OF CHEMICAL EDUCATION
896
APRIL, 1930
Bubbles are often filled with hydrogen t o show the density of this gas in comparison to that of air. The bubble will rise rapidly, because the gas is approximately one fourteenth as heavy as air. Bubbles containing carbon dioxide will descend, for this gas is about one and one half times heavier than air. The three bubbles containing carbon dioxide, as were shown in the drawing, would not remain suspended within a beaker filled with air, for the gas is heavier than air, ss stated above. . . . .
The SOz indicated in the original diagram is, of course unnecessary. There is the further objection that it would contaminate the products of electrolysis. Many contestants seemed to have a mistaken notion as to the voltage necessary to decompose water. As a matter of fact water can be decomposed with an e. m. f. of 1.67 volts, a t which current tension both oxidions and hydroxidions will be discharged. For practical purposes a voltage of 2 to 3 or more is used, for sulfanion (at 1.93 volts) and hydrosulfanion (at 2.63 volts) are then both discharged. From a theoretical standpoint a voltage above three is entirely unnecessary.= One contestant made us a present of the surprising information that the oxygen molecule contains but one atom. If, on second thought, he is still of the same opinion, we refer him to p. 674 of the March number of THIS J O U R NA L where he will find a detailed proof that such is not the case. We were somewhat surprised that no one mentioned the &ect of temperature on the solubility and rate of solution of NaCI. Actually, the temperature gradient is so slight in the case of this particular salt that there is no practical advantage in heating, but we had expected some one to mention that fact. Soap bubbles should, of course, be spherical. Those who submitted the remaining five least-worst papers were as follows: Charles W. Gibson, Warranshurg, Missouri; Mabel Miller, Bluffton, Ohio; Elmer Drumm, Fisher's Ferry, Pennsylvania; Paul Butera, Cleveland, Ohio; Angela Barrios, El Paso, Texas. %SeeWalker's "Iutroductiou t o Physical Chemistry," Macmillan, 1922, p. 369.
Flowers and Fruits Possible under Artificial Light. Flowers, fruits, and vegetables raised by artificial light only in underground hothouses are quite within the realm of possibility, so long as there is a plentiful supply of cheap electricity. So said Samuel G. Hihben, lighting specialist of the Westinghouse Lamp Company, in a report to the Illuminating Engineering Society. Natural sunlight is not necessary for the normal development of plant life, he said. Artificial light has been used with success in the experimental growing of plants in laboratories, and i t is being used now as a regular commercial proposition in the speeding up of the maturing of vegetables grown under glass and the blossoming of cut flowers.-
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