Firefly light like common fire, but cold - ACS Publications

The fireflies, or "lightning-bugs," that dance in the air over twilight lawns carry torches that burn on exactly the same principle as a lighted candl...
1 downloads 0 Views 259KB Size
This becomes especially evident if Werner is compared with Jorgensen, to whom (preceding and contemporaneous with Werner) is due credit for fundamental studies of the metal-ammonia salts. Jorgensen did not wish to break away from the usual inflexible valence theories; his formulas could not give lasting satisfaction, for they aroused no incentive to a further development of chemistry. Furthermore, Jorgensen was not sufficiently informed regarding the inner, theoretical, and experimental relationship of all the various classes of molecular compounds. Mendelejeff was perfectly aware of this inherent connection. I n his text "Foundations of Chemistry," which Werner knew in its German translation, he clearly emphasized the constitutional similarity of metal-ammonia salts, hydrates, and double salts; indeed he also included alloys and solutions in his discussion. However, his attempts to bring order out of this chaos were not successful, although he did demonstrate that the pure valence formulations then in vogue could not be maintained. He was also correct in his systematic placement of certain series of compounds, such as polymeric metal halides, A12Xs, etc. (which he considered as double halides). The privilege of reaching the goal toward which Mendelejeff had turned his thoughts was reserved for Alfred Werner, whose creation of the general coordination theory was the work of a genius.

Karrer, P., Helvetica Chimice A d a , 3, 196 (1920). Minner der Technik, 1925, p. 290, Herausgeber C. Matschass; Schweizerische C&mikerzeilung, p. 73. 1920. Eeiffer. P.. Zeilschrifl j s r angevendte Chemie. 33, 37 (1920). Lifschitz, J., Zeits~hrijtj c r Elektrochemie, 26, 514 (1920). Morgan, G. T., I.Chem. Soc. (London), 117, 1639 (1920). A practically complete bibliography of Werner's publications may be found in ITelsetice Chimica Acta, 3, 225 (1920).

Firefly Light Like Common Fire, but Cold. The fireflies, or "lightning-bugs," that dance in the air over twilight lawns carry torches that burn on exactly the same principle as a lighted candle. That is, they combine a combustible substane with oxygen and produce light. The great advantage the firefly has unconsciously worked out over man-made illuminants is that his tail-light makes so little heat that it can fairly be called a "cold ligbt." The shining of fireflies, and of other animals and plants, used to be called "phosphorescence," because i t looks like the light given off by a bit of rubbed phosphorus in the dark. That, however, is a misnomer, for it is not caused by phosphorus. The basis of the light is a substance called "luciferin," which means "light-bearer." By itself it does not glow, but a second substance known as "ludferase," present in all luminous organisms, causes it to combine with oxygen, and this makes the luminescence. A further chemicd reaction breaks the luciferase away fromthe combination, permitting it to be used over again an indefinite number of times.-Science Service