Cftc ^^opular Science iSctos 



AND 



BOSTON JOURNAL OF CHEMISTRY. 



Volume XXII. 



BOSTON, SEPTEMBER, 1888. 



Number 9. 



CONTENTS. 



Familiar Science. — The AVotulera of Spectrum Analj'sis. 129 



A Few Hours in tlie Glasgow E.\bibition 129 



Kent's Cavern : its Wonderful Story of Prehistoric Man . . 130 



Soap-Bubbles 131 



Chemistry 132 



Scientific Brevities 133 



Pbactical Chemistry AND the Arts. — Tanning 133 



An Electrical-Current Meter 133 



A New Lecture Apparatus for Demonstration of Reflec- 

 tion and Kefraction 133 



An Easy Metliod of Finding the Specific Gravity of Liquids, 1;J3 



The Stolen Secret of making Citric Acid 134 



Verifying Graduated Glass Tubes 134 



An Experiment to illustrate Quantivalence 134 



Laboratory Notes 134 



Home, Farm, AND Garden. — The Chemistry of a Match.. 135 



The Edelweiss 135 



Hops. 



135 



A "lioastof Rubbish " 136 



What the Cow gives us 136 



Horticultural Hints 1.36 



Editorial. — A Curious Experiment 137 



An Immense Bowlder 138 



Fermentation 138 



To ascertain the Distance to the Moon 139 



Meteorology for July, 1888 138 



Astronomical Phenomena for September, 1888 139 



How Birds Learn to Sing ]4(» 



Optical Illusions 140 



Questions and Answers 140 



Literary Notes 140 



Medicine and Pharmacy. — Illustrations of Antiseptic 



Surgery 141 



Successful Modern Dentistry 141 



Kiihnia .-18 a Medicine 142 



Monthly Summary of Medical Progress 143 



The Sightseer's Headache 143 



Some Answers in Physiology 144 



Medical Memoranda 144 



PURLI8UEK8* COLUMN." 144 



iFamiltar Sctente. 



THE WONDERS OF SPECTRUM ANALYSIS. 



The solar spectrum, as shown in the rain- 

 I)OW or dewdrop, has always been a familiar 

 object to mankind ; but it is only within the last 

 quarter of a eenturj- that the marvellous facts 

 written in the rays of light from the sun and 

 stars have been revealed to us. Two German 

 scientists, Bunsen and Kirchoff, first carefull3- 

 investigated the phenomena of the spectra of 

 the light proceeding from various luminous 

 bodies ; and their labors, with those of others 

 following in their footsteps, have opened up a 

 field of investigation which is apparently limit- 

 less. 



It would require too much space to give a 

 complete description of the theory and methods 

 of spectrum analysis : we can only glance at 

 the results obtained. We maj' briefly sa}-, 

 however, that, when a ray of light is passed 

 throngli one or more glass prisms, it is sepa- 

 rated into its constituent parts, or spread out 

 into a broad ribbon containing numerous 

 bright or dark lines, which indicate the 

 presence of different elements, as well as 

 man}- other facts concerning the condition in 

 which they exist. 



One of the most useful applications of the 



spectroscope is to the analj'sis of different 

 substances. The chemist would be unable to 

 detect with his reagents the presence of small 

 quantities of certain elements ; but let him 

 bring the substance into the flame of a lamp, 

 and glance through his spectroscope, and in a 

 moment their presence or absence is indisput- 

 ably proved. A ten-thousandth part of a 

 grain of sodium can be easily detected bj' this 

 means ; and simply- clapping the hands near 

 the flame will give off enough of this omni- 

 present element to cause its characteristic yel- 

 low line to appear at once in the spectroscope. 

 We have b}- this means proved the presence 

 of the rare element lithium, in the blood of a 

 person who had been drinking a mineral water 

 containing a trace of its salts. 



Not onl}- does spectrum analysis show us 

 the presence of familiar elements, but some- 

 times lines are observed indicating the presence 

 of those pi'eviously unknown. CiEsium, ru- 

 bidium, indium, gallium, thallium, and sev- 

 eral others were thus discovered, although 

 present in such small quantities that no ordi- 

 narj' reagent could have detected them. 



But still more wonderful are the facts made 

 known to us when we turn the spectroscope 

 towards the celestial bodies. Everj- ray of 

 light reaching us from the sun bears a message 

 which, with the aid of the spectroscope, we can 

 read as easily as we can read the words on 

 those minute photographs which are only 

 visible through a microscope. The characters 

 of man}- ancient inscriptions arc still undeci- 

 phered ; but the story told by the little dark 

 lines crossing the solar spectrum is perfectlj" 

 familiar to us, although only a few chapters of 

 it have as yet been interpreted. We know 

 that iron, sodium, platinum, and man}- other 

 elements, are present in the sun in the state of 

 vapor; and it has been well said, that if the 

 word " iron " tippeared on tlie disk of llie sun, 

 the proof of its presence would be much less 

 perfect than is that furnished by the lines which 

 it causes to appear in the solar spectrum. 



The spectrum of fixed stars, comets,, ncbuhx;, 

 variable stars, etc.-, all give us an immense 

 amount of information concerning them. We 

 may judge of the temperature of the stars, and 

 calculate the speed at which they are moving 

 toward or from the earth. It tells us that 

 comets are, in part at least, gaseous bodies, 

 and distinguishes between those nebute which 

 are simply distant clusters of separate stars, 

 and those which are masses of glowing gas not 

 yet cooled down to the litpiid or solid state. 

 It told us that the wonderful star which for a 

 few weeks in 1866 blazed out so brightly in 

 the constellation of the Northern Crown, was 

 enveloped in a mass of glowing hydrogen gas. 



and shows us, that, in the sun's atmosphere, 

 there exist substances unknown to us on the 

 earth, which may prove to be the component 

 parts of some of our so-called elements, disas- 

 sociated under the intense heat there prevail- 

 ing. 



The spectroscope shows the presence of 

 more or less moisture in the upper air, with 

 the accompanying probability of rain or fair 

 weather ; it shows the presence of the constitu- 

 ents of blood in solution, besides many other 

 organic substances ; and finally, the spectrum 

 of the light from certain rare metals glowing 

 in a vacuum under the influence of an electric 

 current, proves their compound nature, al- 

 though, to the coarser chemical and physical 

 tests, the}- are simple elements incapable of 

 subdivision. 



Although we have only mentioned a small 

 part of the results attained by this marvellous 

 analysis of light, we have shown its immense 

 scientific importance, and indicated what it 

 may reveal in the future. Hardly a day passes 

 but some new development is brought forward ; 

 and it seems probable, that, if we ever reach a 

 knowledge of the actual nature and constitu- 

 tion of matter, it will be by the aid of the 

 subtile and immaterial rays of light, which, as 

 they flash through infinite space, seem to bear 

 with them, some of the profoundest secrets of 

 the universe. 



[Original in Popular Science KeWH.'\ 



A FEW IIOUHS IN THE GLASGOW 

 EXHIBITION. 



BY K. B. CLAYPOLE. 



A FEW hours is by far too short a time to give 

 to an exhibition so large as the one now open at 

 Glasgow, and so full, moreover, of objects worthy 

 of study. Nevertheless, under good guidance, 

 and with the determination to pass those things 

 which are not especially distinctive of this exhibit, 

 a great deal may be done. Accordingly, on first 

 entering we resisted the temptations of the depart- 

 ment of fine arts, and turned our attention to the 

 chemical crystals, which attracted us greatly; and 

 we had to be reminded that though the exhibit 

 is exceptionally large, there is nothing in it par- 

 ticularly new. We coulJ therefore afford but a 

 passing glance at the yellow and red prussiate of 

 potash, the scarlet bichromate of soda, yellow 

 chromate of soda, soft white soda crystals, bichro- 

 mate of araraonium, and the mass of ten tons of 

 alum crystallized in the form of a hollow cylinder. 

 In the same way we hurried past soap and stearine 

 in every stage of manufacture, from crude and 

 refined oils and other raw materials to shapes 

 and forms demanded by modern civilization; the 

 prosaic nature of the display being relieved by fine 

 stearine statuary, landscapes in mottled soap, and 

 life-size busts of the Queen, members of the royal 

 family, Robert Burns, Sir Walter Scott, Dr. 

 Livingstone, President Garfield, and the Laocoon 



