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Show LIGHT THAT IS INVISIBLE CAN DESTROY GERMS Science Has Developed Instruments In-struments to Detect Rays f the Ere Cannot See. AID IN DISCOVERY OF LUNAR COPPER Remarkable Photographs Are Made by Utilizing These Unseen Lights. BT FREDERIC J. HA8KIN lu no other way is the progresaof cisses brought home mora strikingly than in the development of onr knowledge knowl-edge of invisible light. Not only has the scientist discovered rays of light which the human eye has never seen snd can never see, but he has found how to use that knowlsdgs for the benefit ben-efit of our everyday life. He has found rsys of light to weak that ordinary ordi-nary glsst, howsvsr transparent to ths vision, shuts it out effectively ; and yet they srs so ttrong that billions of germs may be killed merely by coming within the scope of their influence. Prom the dswn of creation to the re cut past they have thed their influence influ-ence upon men, vet men 'have been wholly uncoutcious of their existence. In the few short years that have gone by since their discovery wo have dem onttrated that even In the inkiest of darkness there may be brilliant lights. Such a paradox could not be believed by the ordinary layman did not the eye of the ramera reveal ite truth. That instrument shows us that the eyt Is sensitive to only a very small propor mm of the total radiation that reaches it, a discovery that leads the scientist to believe that if the eye eoold recognize recog-nize all this radiation it would reveal a thousand wondrs undreamed of. Gradually the scientist it developing refined instruments which sre capsbie of detecting what the human eye cannot can-not perceive, and it is believed that MSSf uew things will ultimately b learned through them. Dr. R. W. Wood, professor of experimental experi-mental physics at Johns Hopkins university, uni-versity, it one of the world's authorities authori-ties upon invisible light, and he illus-trates illus-trates tome of the remarkable things about invisible light. For instance, he says that if the finger be dipped into MM oxide and rubbed over a white sheet of paper the eve will be unable to detect the presence of the ttreakt of the white powder, unless it hss Wen very thickly applied. If, however, that piece of paper bo photographed with ultra violet light, it appears to be marked with ttreakt of charcoal. Thit experiment led to the deduction that if the moon and planets he photographed with invisible light, substances which do not appear visually might be brought out. Discover Sulphur on the Mooa. Is a demonstration of this theory, Dr. Wood had constructed a sixteen-inch sixteen-inch mirror, of twenty-six-inch focus, k. coated with nickel, which is used in BV ilMSblsalitS with a plate of the nsw ultra violet glass, heavily silvered. The region around Aristarchus, one of the craters of the moon, was photographed with yellow aud then with ultra violet light. Then two specimeut of volcanic tuff were photographed in a timilar way. It wat found that the one sample, sam-ple, when photographed with ultra vio let light, corresponded identically with the deposit surrounding the crater (Continued on page 2.1 used with great rare The quarts aser-enry aser-enry vapor lamp is fad by a continuous electrical current, lis running la regulated regu-lated by? a eeatiael lamp In the same circuit or by aoting Ue own state of luminosity. To light It the operator simply shakes the thread of mercury until the two poles are eo&Bertad. Then the lamp la eat ia normal position, the thread af mercury Is broken but the eleetric current eoatinuea to paaa through the luminous vapor Indefinitely. Several French inventors have perfected per-fected a little lamp of this hind which may be used to sterilise potable water In hotels, hospitals, private houses and the like. With it they have been able to hill Be many aa a billion colon bsc.il li per cubic centimeter a million times as many as are found in the moat impure im-pure drinking water. They simply pas the water through a tube containing the light, aad it does the reel. Not only doee it hill the germs them- elves, bat it la equally fatal to spu es. In water polluted with 128,000.000 bacilli ba-cilli to the quart, these bacilli having sporaa which could resist boiling for several hours, not a single spore was able to eeeape alive when the water was running through the tnbe containing the mercury vapor lamp at the rate of four-teen four-teen gallon-, an boar. By the application of this system city water supplies can be made as pure a though taev came from the unsullied snows of- high mountain peaks. Large mercury vapor lamps need onlv to he immersed in the water that flows throng a city's mains, and as it passes within the neighborhood of the burn lng lamp untold million of germs are electrocuted everv instant bv a fluid more subtle aad more remarkable than electricity itself. Tomorrow: THE PA8SENOEB PIC.EON . . - i Dr. Wood aad Professor stolisni devised de-vised a sort of ray (liter with which they could separate the visible from luo tavialble rays of light, Bad with It they ware able to isolate the longest heat wave ever diaeovorbd. It consists of a box la which is imprisoned aa elsctns spark. The ultra violet rays of light from It are brought to s focus upon a small circular s porta rs upon a sard board seres a, aad ths focal length of the lens Is mads so great that the visible visi-ble rays caaaot corns to a focus at all. Held before the light white paper was black, but when uranium nitrate crya tale ware substituted the pressure of the nitre violet rays was mads manifest mani-fest by the crystals shining with a brllliaat greea light. Metallic mercury vapor shlaee with a brilliant light whoa exposed to the invisible ultra violet raya. Dr. Wood kaow something of this, aad la order to determine the amount of absorption he sealed up a drop of mercury ia as exhausted flask of quarts and roeosaed the light of the mercury are, horsing la a si) lee tube, upon the center of the bulb. Whaa the bulb was pbotograplied with a quarts lsns the picture showed a coss of foeueeed rays, precisely as if the bulb ware filled with smoke. This Is another very good example of how new discoveries may be made by ultra violet photography. Make Wonderful Photographs Many remarkable coadilioaa are revealed re-vealed whaa lovisibls light photographs are made. The usual method o- shutting shut-ting out ike vial hie rays and admitting the iafra red rays of light is to com bias a aheat of the densest blue cobalt glees with a solution of bichromate of potash or soma suitable oraage dye. Here is a picture taken by this method in which the sky la black, and yst the vegetation and the grass appear to '-a saow whito although the picture aoiuea from sunny Italy. The shadows In this picture are Intensely black, since the camera with this filter on it perceives only the direct light of the eun and does aot catch the indirect light of the sky. This Is said to bo Ue way things would look to the human eye c-n the moon, where there 1b bo atmosphere to form a luminous sky. Quite a different impression would we have of our surroundings if the eye were sensitive only to ultrn violet rays. To see how things would look with them ere have to avoid glass, for glass is aa opaque to them as a black slate is to the aye. Quartz, however, is traaspareat to them, aud when we find some substance that they caa get through and whieh wilt yet refuse tn recognise the visible rave, we will have solved the problem. Metallic silver if the substance we need, and it is the only substance known that fully recognises recog-nises every ultra violet ray and throws out every visible ray. A very thin film of It most be deposited over the surface sur-face of the quarts. With this pictures that seem like views of fairyland may be taken. Chineee white appeara black as the ace of apades in this lulu. White flowers in the garden become al most black, aad a number of striking contrasts result But the most remarkable property of ultra violet light Is not the effect it has upon the photoffraphle plate, but Its garmieidnl qualities. We have long known that the son's rays tend to kill germs, bat It eras aot unt 1 recently that the discovery was made that it was ths ultra violet light that thev contain that does the work. The son's ravi are comparatively poor in ultra violet Ueht, for bnt little of it is able te struggle through the entanglements ot oar atmosphere. Therefore we mus' look mainT to artificial source for om nltrs violet Hgbt for germicidal use The merenrv vapor light vrih a quarts tubs Is the beet eooree. Ultra violei rave of small reave length are ven nocuous to all l'ving ce'ls aad tbereforf the microbe hlHIn" lsm-nw have to 1" LIGHT THAT IS INVISIBLE CAN DESTROY GERMS (Continued from page 1.) Aneterehue- It was analysed and found to contain Iron and traces of sulphur. Then several rooks wsra floated float-ed with Iron oxids, and they were photographed with ths ultra violet rays, but the Iron showed nons of tha peculiarities of Aristarchus when so photographed. After this an invisible coating of sulphur waa formed on a piece af light gray roek bv the application appli-cation of a fine let. When it waa photographed with the invisible ray it was black exactly like the crater Aria tfh"T From this Dr. Wood was able to later that this spot oa tha moon ia an extensive deposit of sulphur, result in from vapor ejected from ths orator. To explaining ths mysteries of invisible in-visible Light before the Borel Institohion of Great Britain, Dr. Wood took two pieces of searlst silk, whiofc eoald not be distinguished under an incandescent light, and placed them under a Cooper-Hewett Cooper-Hewett mercury are lamp, with the result re-sult that oae eaattaued to appear scarlet scar-let while the other appeared almoet black. The mercury lamp gives off almost al-most no rod raya, consequently red objects ob-jects appear almost black. But the other piece of silk was colored with a dye that barams fluorescent under the |