Galitzin seismograph at Georgetown University, Washington, D.C. The round weight, in the instrument to the right, remains stationary during an earthquake, while the other parts move up and down around it. Attached to the weight are small coils of wire connected to the galvanometer in the center. The coils are between the poles of the magnet, and their motion relative to the magnetic field produces a minute electric current which is detected by the galvanometer and recorded photographically in the apparatus to the left.
Gas made from bituminous coal was declared the ideal household fuel of the future in a report by Prof. S.W. Parr of the University of Illinois to the first national fuels meeting held recently in St. Louis under the auspices of the American Society of Mechanical Engineers.
Charging that the average home and apartment heating plant is guilty of producing most of the smoke nuisance of cities today, Prof. Parr predicted that raw coal would eventually become obsolete as a fuel and that instead the soft coal would be processed to produce a solid smokeless fuel more desirable than anthracite, gas of high quality and tar from which drugs, dyes and many other chemicals can be obtained. Smokeless combustion, high efficiency, cleanliness and convenience give gas a status unapproached by any other fuel, Prof. Parr declared.
The chemistry of soap-suds was elucidated by Prof. W.D. Harkins of the University of Chicago. In the cleansing process the minute particles of soap capture and carry away drops of grease by surrounding them. The droplet of oil is too small to be seen, being only about one ten-thousandth of an inch in diameter, yet it requires twenty million molecules of soap to surround it with a film one molecule thick.
The soap molecule is fitted to act as the connecting link between oil and water for it consists of a long thin chain of carbon atoms, with one end of an oily mixture and the other more like water in composition. All the molecules of the soap line up in the same position around the oil drop with oil-like tails turned in towards the oil and with water-like heads sticking out towards the surrounding water. The oily ends are charged with negative electricity, so the oil drops are kept apart by the mutual repulsion of the negative charges. Thus particles of dirt or grease can be held in suspension in water in the form of an emulsion although they are insoluble in water.
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