Show peaking CRYSTALS OlE Latest MARVEL I tt O p. p aw CN o aw ow a uT ALI wear tZ Kr O MCI olM 0 O VY 2 It G re e i D j. 1 IN r CUP I tt If Jr 1111 fJ 0 1 t MAKING l THE SEED SEMI CRYSTALS 0 1 ft the recent convention in Wa Washington hington of th International C Communications n n Council there was shown a marvel of Am American cal ng nulty that the ultra-modern ultra burglars burglar s n i to overlook On One of r the exhibits of mm Council consisted ed of a devi device e cables nables bleS any anyone one to open a safe without ut ng gItt lt or knowing the combination With 1 of Rochelle salts and a sound amplifier the noiseless isei ss falling of the tumblers i Is m mag- mag g. g many mariy many times dines s. s hello helle h ll salt crystals it was explained twist sh shape pe when agitated setting up an electro electro- force r e. e When connected with the safe eafe h he vibration of the tha falling tumblers rs is throw the salt into spasms The Th whis- whis moan of complaint Is magnified hu in m th the am- am d to another crystal and bea be- be a veritable shriek of agony e of Df the most unique inventions at at least ne he scientists scientist's standpoint standpoInt-is is the wonderful effect of Rochelle crystals In th these se a veritable new gold mine h has s been opened to all experimenters What these crystals will all do fairly staggers on ones one's s 's imagination im g n. n Think of a simple salt crystal that will actually talk that c can n be a telephone receiver a transmitter combined that will give as S m much ch as volts when sq squeezed with two fingers finger that will sing when current is supplied to tl it iti And the best part is every one c can n make his own crystals and perform these experiments without h having ving to buy this century electrical wonder a full fall d de description de- de of of which i is gi given en in Science and Invention Ith Invention 1 tion by A. A McL l Electricity discovered by J. J And P. P Curie is the na name 1 given to a crystal source of electricity In this c case se electric charges of different different different differ differ- ent signs are Elre lib liberated rat d on different surfaces of a cr crystal st l when mech mechanical stresses stress s or Vibrations vibration's are impressed impress d on certain of its parts The word won is derived from the Greek signifying signifying signifying signify signify- ing to press hence press pressure re electricity Not every crystal is electrically active Nature grows crystals crystal whether mineral or or- or 4 J ganic ganie in 32 differing class classes s of f structure of ure-of ure of these just 20 classes offer the ner necessary sary condition condi ondi- condition tion for ele electric activity And nd this Uti condition condition condition condi condi- tion is asymmetry symmetry of structure or of f molecular arrangement While a 11 very large fi number t ber of crystals crystals crystals crys crys- have hav the electric property only c comparatively few exhibit the phenomenon to a a. a sufficiently h in interesting interesting interesting in- in degree to warrant mention of it at this time Among mineral crystals crystale qu quartz and to tourmaline tourmaline rm- rm line are arc the best known having the asymmetric etric structure the structure the molecules consisting of or regular regula bricks brick are staggered int into a skew symmetry or spiral structure In the case of the organic crystals crystals crystals crys crys- the molecules themselves are asymmetric that is to say they do not comprise regular bricks They have in fact little skew symmetries symmetrIes symme symmetries symme- symme tries of th their ir own Both the mineral and md the organic organic organic or or- ganic crystal exhibit their respective asymmetries tries as right or left-handed left skew structures This t i is revealed in th their ir power to rotate the plane lan o DI of polarization of polarized light in corresponding right or left directions Scientists are more interested in the organic organic organic or or- ganic crystal since this type comprising as it d does doe's es th the asymmetric carbon molecule has ha's proved to be m more re susceptible of large electric ef ef- ef- ef Examples of active organic crystals are ares s sugar gar camphor tartaric acid etc A crystal which is is very active pi electrical electrical zo-electrical- Jy i is r rotary t ry sodium potassium rat or Rochelle S salt lt Recently Ain American ric n chemists h investigated t d th the poss possibility of d developing v l pi g P. P electric zo r c-r crystal rf s state laIt la It was soon found that c crystals atals of f Roch Rochelle salt would give good results result's if pr prepared pared in a special ap i l manner Briefly fly increased etti efficiency i ncy is brought about b ut utby by the following conditions condition 1 Selection of particular r habit of bf growth 2 Desiccation Preserving b by exhausting the moisture re 3 Development of the crystal into a o com composite m- m polar structure 4 Application of static compression 5 Use f bf electric poles normal t to U. U each h oth other t 6 Application of torque Roch Rochelle lle bIt Bait crystals are grown fro from nuclei 1 or seeds seeds of definite form These ai ate are obtained by selection from cr crystal st l cr spontaneously spontaneous spontaneous- ly grown in ih a supersaturated d solution of f ih the s salt lt The solution should be made u Up of 6 parts Rochelle Ro Ro- R Rochelle chelle salts to parts of f wa water r. r The density ty of the solution n at 50 d deg g. g C. C is and acid il the n nuclei l i from which h large crystals are gt grown wn are r planted plant ed in the m mother her liquor when the t temperature has dropped to 38 deg C. C The crystal l gr grows ws lap rapidly as the temperature bf th the liquor r f falls falle to that of its surroundings Th The seeds ate re selected t d so that th they y are practically square shaped the the d-the the seed for this purpose mu must t lie Ho w with h Its Us principal or optic axis in a horizontal plane When a k crystal is grown very ery rapidly rapidly-ae r rapidly as by bythe bythe bythe the method d described it It temperature gradient d develops vel ps a composite structure termed by min min- mineralogist rat gilSt the hour ih Important Uil fibs use is made of this structure and its d development ve is fully encouraged It Is found th that t if th the c crystal t when grown to the tha desired size ft from m 30 to grams and wb when n thoroughly thoroughly- desi desiccated or r dried develops n new w and stronger electric pol poles s on tm its surface Th The vertical walls wall surrounding g the principal axis f form m one pole while white the two horizontal nial or r bb basal l pt planes pianos n s. s t together ge her form th the other p pole l serve as electrodes when applied t to ih the crystal Since compression gre greatly Uy il improves proves th the electric eff effect ct in these crystals an appliance p called the |