I N D U S T R I A L A N D ENGINEERING CHEMISTRY
890
Radiotrons
The effect of motion of such electric charges is also to be seen by using a simple antenna and wireless tube so connected that the charge produced on the antenna interrupts a lighting current which is flowing through the wireless tube, or radiotron. This is imitating the effect produced by the induced charges which ordinary wireless antennae receive from the passing electro magnetic waves. The extinction and lighting of the lamp replaces the ordinary sounds heard in the headset of the well-known wireless receiving apparatus. High-Frequency and Gas Tubes
The presence of electrical energy in space can also be shown by what may be called a very small wireless sending station. In this case the electrical fields are reversed several million times a second. Thereby there is across the space in the neighborhood an exceedingly high voltage, because the induced voltage is proportional to the velocity of cutting of the lines of magnetic force. For this reason current is produced in whatever conductors are near the apparatus. When I bring near it a group of long glass tubes containing various gases a t low pressures the gases glow, owing to the current. A useful application of this principle is the Northrup highfrequency induction furnace. It enables one to electrically heat substances which are conductors without having to fasten current-terminals to them. Barkhausen Effect
There is another experiment which, although it may not help answer the question-Is there anything in matter?bears on something that is put into some matter and taken out again, with peculiar effects. I refer to magnetism. I incase a piece of iron wire about the dimension of the graphite in a lead pencil in a small rubber tube, both to insulate i t and make it visible, and bend the whole into a U shape, so that I may insert it into a pair of fine wire coils. These may be called exploring coils. They are connected to a delicate current-amplifying set and to a loud speaker.
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Any change in magnetism in the iron will then be communicatkd by ihe loud speaker. Originally, the wire was not magnetized. When I bring a permanent magnet near the small wire, the latter is temporarily magnetized, and this property is removed, or it soon decays, on removal of the large reducing magnet. The peculiar thing about this Barkhausen experiment is that it seems to show that the iron magnetizes by myriads of small units, or by jolts, and it demagnetizes in the same way. This is true through the whole range of its magnetization. At every increment, as may be seen by bringing up the large magnet in steps, there is a noise, such as is usually made by very many sudden individual noises, and the greatest effect comes on the most complete reversals of the applied field. It looks as though multitudes of atoms, or atomic groups, were answering to the action of the large magnet. This corresponds in general with the assumption of induced orientation of very many small continuous-current orbits, or small polar magnets. I do not know exactly what is taking place, but it must finally fit in with the fact that practicallyonly iron and nickel are very magnetic, and they in turn are composed of a certain collection and arrangement of electrical charges. Conclusion
Experiments have shown that matter is electrical and that it is separable into its electrical charges. Moreover, whatever electrical charge may be, it is spotted. In other words, it is localized in finite units at points in space. There seems for the present to be no cure for our belief that there are two kinds, which we call positive and negative. Wherever these different kinds are stored in equivalent amounts we have what we call ordinary or neutral matter, and the kinds of this matter depend on the numbers and space arrangements of these charged spots. Even as matter, they are still spread out so extensively that they closely resemble the starry heavens, where thousands of light-years separate the stars. But, just as our knowledge of the stars themselves is continually increasing, so we may be sure that we may go on extending our knowledge of electric charges.
Rapid Method to Distinguish Zinc Oxide and Lithopone Pastes' By Edward 0. Dunkley S A N B i B G O . CAGIF.
BOUT five years ago the writer examined a 50-ton A shipment of zinc oxide ground in linseed oil, as another laboratory had previously reported lithopone in one out
of six samples. Although a few more kegs were examined without finding lithopone, it was finally requested that the matter be settled by making individual tests upon the remainder of the 1000-keg shipment. The numbered kegs were punched with a I-cm. hole, and the paste was sampled into paper envelopes by means of a glass rod. To minimize time and fatigue with such a large number of samples it became necessary to cast about for a rapid and positive scheme for qualitative identification. If hydrochloric acid is poured on lithopone paste, bubbles of hydrogen sulfide will generally be evolved, but some samples of lithopone paste have failed to respond to this test. It seemed possible that the color and stability of silver 1
Received May 22, 1925.
sulfide would serve as the basis of a delicate and rapid test. This was found to be the case, as a solution of silver nitrate markedly acid with nitric acid turned the lithopone paste black, whereas the zinc oxide preparation remained unchanged. To apply the method expeditiously a large glass photographic developing tray was placed over a white background marked off into numbered squares. Small portions of the samples were then transferred to the glass over their respective numbers, and the solution of silver nitrate and nitric acid (which may be of any moderate concentration) flowed over them. About sixty samples were treated a t a time, and as the reaction was practically instantaneous the entire number was disposed of in a few hours. The samples that gave the color change were subsequently checked by the quantitative examination. In this particular shipment only 13 of the 1000 kegs contained lithopone.
