ect upon for 1,000 hours without appreciably deteriorating. small insects. A common fly dies within one minute cine has disclosed certain properties of this form of radiant energy, which are not only -highly interesting when brought to a distance of about 14% centimeters of —<_<____—_—__>~--o--+… … detailed set of rules for the contest. 50 to 150 grammes of mercury, according to its size. THE RESULT OF A FIFTEEN MINUTES’ EXPOSURE TO This mercury not only furnishes the vapor necessary 8 THE RAYS OF THE UVIOL LAMP, Tunnel Ventilation. for the working of the lamp, but also serves for start- In a…
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