VOL. 3, No. 4 VALENCE THEORIESTO INORGANIC CHEMICAL REACTIONS
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$ =s As: IS S ASXIS ::~+2~~+-?+ :=s+23rs As$3 Na+-~ As$3
:Is
While the polysulfides do not act as reducing agents as the peroxides do, the simple sulfides can reduce many other atoms because of the tendency of the sulfur atoms S-- to lose two electrons and become free sulfur. An illustration of the reducing action of a sulfide is that of hydrogen sulfide upon ferric chloride in acid solution. The electronic equation is:
The sulfur here tends to lose its two electrons and become free sulfur, which is precipitated from the solution. Each of two atoms of ferric iron gains one of these electrons given up by the sulfur and becomes ferrous iron. By the precipitation of the sulfur from solution a reversible reaction is prevented and the ferric iron can be completely reduced to ferrous iron.
Polarized Light Speeds Growth of Bacteria. Germs grow faster when they get their light arranged in a certain way, according t o the results of the investigations of two Indian scientists, S. S. Bhatnagar and R. B. Lal, of the University of the Panjab, Lahore, who have just reported t o the scientific journal, Nature. . The two experimenters took cultures of the germs of typhoid fever andcholera, and exposed one set to ordinary light, while the second set was placed under a beam of polarized light. Polarized light differs from ordinary illumination in that the fronts of the light waves are all arranged in the same direction, while in ordinary light they criss-cross at all angles. The germs seemed to thrive much better on polarized than on ordinary light. Scientists have been much interested lately in the effects of polariredlight anliving things, since discoveries made by Dr. Elizabeth S. Semmens of Bedford College, London, indicate that the digestion of starch takes place more rapidly under its influence.Science Service
