The riddle of the chemical nature of tuberculin, the substance used for detecting tuberculosis in cattle, is a step nearer solution through researches reported by Dr. Florence B. Seibert of the University of Chicago.
There has always been a question, Dr. Seibert stated, whether the specifically potent factor is a protein or merely an infinitesimal amount of some very highly active substance attached to the protein. The difficulty in solving problems such as this has been due to the fact that the purification of proteins is one of the most difficult of all tasks in chemistry. In her laboratory, however, efforts to obtain a purified product have succeeded in producing an active protein in crystalline form. One of the surest tests of chemical purity is obtained when crystals come out of a solution; mixed materials do not crystallize.
Red stars, like Betelgeuse, the northernmost of the familiar group of Orion, which will soon appear in the east as a conspicuous feature of the winter evening skies, are probably spotted like the sun. This is the opinion of Dr. Joel Stebbins, director of the Washington Observatory of the University of Wisconsin.
In collaboration with Dr. C.M. Huffer, Dr. Stebbins has made tests of the light of different classes of stars by studying typical samples of each. The white and yellow stars, he says, appear to be fairly constant but about a third of the red stars, including all of the biggest ones, vary in light. Some change as much as 20 percent in a few weeks. As an explanation of this he thinks it probable that these are covered with spots, and that as they rotate, a greater or less area of luminous surface is exposed to the earth.
The "quantum," the "atom" of which modern physicists suppose that light and other radiations consist, may be divided. This is indicated by experiments of Dr. A.J. Dempster, of the University of Chicago.
In the experiments he obtained light from a single vibrating atom, instead of many, as in the ordinary light source. But though the light is supposed to consist of single quanta, it behaved just as does ordinary light. When allowed to fall the light was reflected, and part passed through. When this was recombined the same patterns of light and dark bands were produced as would come from ordinary light.