Vol. XXII. No. 12.] 



POPULAR SCIENCE NEWS. 



175 



the night air, ready to be deposited as dew? and 

 where is it gone to now, and what changes will it 

 undergo? The dew-drop has become invisible, but 

 is it lost? No; no atom of matter can ever be lost 

 or destroyed, or cease to be of use. It is as impos- 

 sible to annihilate an atom of matter as to create 

 one. The liquid gem that glistened in the rays of 

 the morning sun disappears from view, but in the 

 form of invisible vapor it may be inhaled by the 

 breathing leaves of plants or trees, or it may rise 

 to become again visible in the floating cloud, and, 

 by reflecting and refracting the solar rays, may help 

 to paint the glowing sunset. Tomorrow it may 

 descend to the earth again as rain, to be drunk up 

 by the roots of some thirsty plant, or serve to re- 

 fresh some happy singing-bird, so entering into 

 the composition of animal or vegetable form; or it 

 may trickle through some crevice in the ground 

 into the reservoir beneath, and, mingling with the 

 streams that flow in the interior of the earth, may 

 ooze out again in some cool spring, join the stream 

 of the valley, rippling and dancing on its way to 

 swell the volume of the river, dash down the water- 

 fall, and then emerge into the ocean, there to be 

 again evaporated by the sun, or sparkle on the 

 crest of the wave that the tide rolls in ujwn the 

 shore ; or the dew-drop that to-day is exhaled from 

 the heart of a flower, and rises to become cloud, 

 may be carried by winds hundreds of miles away 

 into colder regions, and fall in the form of hail or 

 snow. It may roll down in the avalanche into the 

 valley, or, falling as a snow-flake on some lofty 

 mountain-peak, it may form part of the glacier or 

 ice-river that glides slowly down the valley into 

 the sea. There it dips down into the water; but, 

 ice being lighter than water, it tends to rise to the 

 surface, and occasionally immense blocks of ice are 

 broken off and float away. These are the icebergs, 

 which, floating into warmer latitudes, gradually 

 melt and mingle with the waters of the ocean. 



But through all these various transformations 

 the dew-drop continues to be water. Its changes 

 from solid to liquid and from liquid to aeriform 

 are caused by differences of temperature. These are 

 physical changes. It may, however, undergo chem- 

 ical changes, by which it may cea.se to be water in 

 any form. Water is composed of two invisible 

 gases, — hydrogen and oxygen. Oxygen has a 

 strong affinity for iron. If the dew-drop is depos- 

 ited on iron instead of a leaf or flower, the iron 

 robs the water of some of the atoms of oxygen, 

 and lets the hydrogen go free. This union of iron 

 with the oxygen of the water forms the thin film 

 of rust, or red oxide of iron, observable on iron that 

 ha? been exposed to dew or rain. 



In other ways also water may be decomposed, 

 and its oxygen or hydrogen enter into the composi- 

 tion of other substances. So the dew-drop we ad- 

 mire to-day may continue to be water in the form 

 of vapor, or liquid, or solid ice, or snow, for thou- 

 sands of ages ; or it may be decomposed in a few 

 hours, and cease to be water in any of its forms. 

 Xor can we tell how long the dew-drop has been 

 water. It might have been water in some form for 

 ages, or it might have been created by the decom- 

 position of some other substance a few hours ago. 

 Coal-gas, which is used to light the streets, contains 

 hydrogen, which in burning unites with the oxygen 

 of the air to form water, which passes away as in- 

 visible vapor. The watery vapor, therefore, which 

 has been condensed to form the dew-drop, may 

 liave been produced during the night by the burn- 

 ing of the gas in the streets. The cool dew-drop 

 might be born of the burning flame. Its atoms 

 might have been sleeping for ages, hundreds of 

 yards below the present surface of the earth, in the 

 coal-bed composed of the vegetation of some forest 

 of the ancient world. Or they might have entered 



into the formation of some limestone rock on which 

 the beds of coal rested, or the more ancient granite 

 rock, still lower down in the earth. There each 

 tiny atom might have done its best for ages to up- 

 hold the mighty mountain above it, till, rent by 

 earthquakes or melted by internal fires, and poured 

 forth from the crater of some volcano, it was again 

 brought under the influences of sun and air, of heat 

 and light, and moisture and frost, and subjected 

 to physical and chemical changes, till it came to 

 sparkle in the morning dewdrop. 



But, whatever wondrous transformations the dew- 

 drop may have passed through, we know that it 

 existed even when there was no cooling dew, nor 

 thirsty flowers, nor forests, nor fields, nor lofty 

 mountains, nor pleasant valleys, nor rolling rivers, 

 nor widespread ocean, nor solid land ; when the 

 earth and all it now contains was vapor. " The 

 earth was without form and void." During ages 

 longer than we can count, this great mass of vapor 

 cooled down till some parts became solid; some 

 still remain fluid, and others gaseous, as the air 

 that surrounds the globe. From a shapeless mass 

 of vapor it has been slowly transformed into the 

 beautiful world it is to-day, where flowers bloom, 

 and birds sing, and children play. During all 

 those long ages each atom in the dew-drop has 

 existed somewhere in some form. Each atom of 

 hydrogen or oxygen or each molecule of water has 

 done its duty and served some useful purpose. So 

 it will continue to do in the countless ages to come. 

 It will never be destroyed nor lost. It will be use- 

 ful or beautiful somewhere for ever. 



How many questions must be asked and an- 

 swered, how much and how varied information 

 must be obtained, before we can understand the 

 history and mystery of a dew-drop! The tiniest 

 object in nature may suggest inquiries which may 

 lead us into delightful paths in the broad fields of 

 knowledge. A flower, a grain of sand, the com- 

 monest pebble you can pick up in the road, have 

 each a wonderful story to unfold to those who take 

 the pains to inquire and learn. So with this drop 

 of dew. If we would follow out all the inquiries 

 it suggests, we should have to study those same laws 

 of nature that made the dew-drop round and the 

 earth a sphere, and control the motions of planets 

 and stars. We must learn how the dew-drop dif- 

 fers from a rain-drop, or the hailstone or snow- 

 flake, or from cloud and fog and mist, into all of 

 which it may be transformed. It is one form of 

 water. Water has compressibility, specific gravity, 

 and other physical and chemical qualities which 

 enable it to perform very important uses in the life 

 of animals and plants, and in the formation of 

 wells in the earth. On the surface of the earth 

 water occurs as lakes, streams, rivers, and the great 

 ocean. .So we should have to learn the influences 

 of the ocean, lakes, and rivers on the climate of 

 the globe, and their uses to man; and watersheds 

 and hydraulic engines would demand attention. 

 Then, water occurs in the form of rivers and lakes 

 underground, where it is an active agent in caus- 

 ing earthquakes and forming caves. It reappears 

 as springs which are sometimes fresh, sometimes 

 salt. Some springs contain large quantities of 

 mineral matter; some are cold, some are hot. In- 

 termittent springs, geysers, artesian wells, would 

 form subjects of inquiry. A whole chapter is 

 required even to indicate the various subjects of 

 study in many different sciences that must be 

 pursued, and a lifetime may be spent in acquiring 

 the knowledge that is necessary to enable us to 

 understand the history and mystery of a dew-drop, 

 —* — 



The famous pear-tree planted in 1630 by Gov. 

 Endicott at Dan vers, Mass., having reached the age 

 of over two hundred and fifty years, died recently. 



[Special correspondence of The Popular Science Newe.'i 

 PARIS LETTEE. 



Studies and experiments concerning infectious 

 diseases are always very numerous, and Professor 

 Pasteur has opened new ways to medicine, and most 

 of the results obtained in the new field are of real 

 importance. Concerning the rabic virus, M. Gal- 

 tier of Paris has made some interesting experi- 

 ments on the resistance of this virus to desiccation 

 and to cadaveric putrefaction. The point is one 

 of importance, as it is very useful to know how 

 long dried or putrefied rabic virus remains danger- 

 ous. Dried virus loses its virulence in a pretty short 

 time, according to M. Galtier's experiments; the 

 minimum being four days, when the rabic matter 

 forms only a thin layer. Hence the conclusion 

 that clothes contaminated with rabic virus cease to 

 offer any danger when they have been allowed to 

 dry during five or six days. M. Galtier considers 

 also that it is quite useless to taboo the pastures in 

 which rabid animals have been, during a month or 

 two, as is often done, and believes that an inter- 

 diction of four or five days is enough. It is not 

 enough, however, for contamicated waters, as the 

 virus remains virulent a much longer time in water 

 than when dried. 



M. Galtier showed, a year ago, that the medulla 

 oblongata of a rabid dog, buried fifteen days, 

 keeps all its virulence; new experiments have 

 demonstrated the fact that the virulence is not 

 abated in the corpses of rabid animals, even 

 after thirty and forty-five days' inhumation, when 

 the venom centres are putrid and diffluent. This 

 fact is an important one also, since, even after 

 five or six weeks, it can be positively ascertained 

 whether a suspected animal was rabid or not. 



Although the opinion of physicians and physi- 

 ologists often varies as concerns the toxic effects of 

 copper salts, it is generally considered that the use 

 of copper vessels in culinary operations is detrimen- 

 tal to health, and nickel has been much praised as 

 a substitute for copper. MM. Laborde and Kiche, 

 after many physiological experiments, have come 

 to the conclusion that nickel salts must be absorbed 

 in considerable quantity before becoming obnox- 

 ious, and that the use of nickel vessels in culinary 

 or pharmaceutical operations is without the slight- 

 est danger to health. 



Recent experiments on the effects in the human 

 body of the new French balls (Lebel gun) have 

 shown many interesting facts. The ball of the 

 Lebel gun is a small one (8 millimeters diameter, 

 instead of 11), which travels faster than those for- 

 merly used (570 meters per second, instead of 450), 

 and is clad in a dress of maille-chort [German-sil- 

 ver], which gives it a greater hardness. It pro- 

 duces much smaller wounds, and these are more 

 limited than with the other balls ; bones are not so 

 much shattered; and the fact that' the ball does 

 not (up to the distance of 1,200 meters) remain in 

 the body, renders the treatment much easier. The 

 Lebel ball may be considered as a humanitarian 

 and philanthropic instrument, in a large measure. 



Tuberculosis is being studied with much zeal 

 in all parts of the scientific world, and many new 

 methods of treatment are being experimented, of 

 which most are based on the antiseptic principles. 

 Tannin, hydrofluoric acid, iodoform, aniline, have 

 been successively praised and more or less aban- 

 doned. Now M. Halter proposes hot-air inhala- 

 tions once or twice a day, lasting a quarter or 

 half an hour. The temperature of the air, which 

 must be quite dry, must be between 248° and 

 374° F. , so that the heat of the iutrapulmonary air 



