‘ nes aan tare ent eee eri er wo 2 . @ flet c00 tg er nae Henne wee ary (Me ee nae yaaa BENE eee a wee , eran . a . sent . a ohm te re aed reer) Sana tree e Pa ae in Sate me We ev deatboe gat Ox Sr erararer racine Sorin) era ' veseee ' Vee tren ai te Peruri air ver ar ie ear Or rn fe ee ee oe oe. / oa ope alee et ae VYA-tw A Pr THE AMERICAN JOURNAL OF SCIENCE. Epiror: EDWARD S. DANA. ASSOCIATE EDITORS Proressorns GEORGE L. GOODALE, JOHN TROWBRIDGE, W. G. FARLOW anp WM. M. DAVIS, or Camsringe, Proressors ADDISON E. VERRILL, HORACE L. WELLS, L. V. PIRSSON anp H. E. GREGORY, or New Haven, Proressor HENRY S. WILLIAMS, or Irwaca, Proressor JOSEPH S. AMES, or Battimmore, Mr. J. S. DILLER, oF Wasuineton. FOURTH SERIES VOL. XXXI—[WHOLE NUMBER, CLXXXI.] WITH FOUR PLATES. NEW HAVEN, CONNECTICUT. iG etenlige 28101 BF ge . MEE iM agit 1) } : frets +3 are av CONTENTS TO VOLUME XXXI. Number 181. Page Arr. I.—Gravity Determinations at Sea; by L. A. Bauzr.- 1 II.—Stratigraphy of a Deep Well at Waverly, Ohio; by R. She LSU NSS EHTEL <2 pS a ee ree III.—Solid Solution in Minerals with Special Reference to Nephelite; by H. W. Foorr and W. M. Brapuny--.--- 25 IV.—Fossil Evidence of the Age of the Virginia Piedmont Slates; by T. L. Watsow and S. L. Powntt _--------- 33 V.—Native Gold from Gold Harbour, Queen Charlotte lisllewngls; @ loyr dies Lei, 1B), Cor/g IN eieced ee Ses cee ee 45 VI.—Natramblygonite, a New Mineral ; by W. T.Scaatiter 48 VII.—New Emission Theory of Light; by J. TRowsripecE. 51 VIII.—Origin and Peopling of the Deep Sea; by J. DNV WAGTISTSETINRCm Meee eee a armalner a anit 2 Ls SS ud rete A ee 55 IX.—Camels of the Harrison Beds, with Three New Species ; loge 15 18, ILO IS e eee ate ee ane eee Se ee 65 NVAIETANT EDN RM mRE ee 2 ke lh ase oo (Al SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Preparation of Metallic Radium, KE. EBLER: Reduc- tion of Oxide of Iron by Solid Carbon, CHARPy and BoNNEROT, 70.— Action of Light upon an Hlectrie Cell, H. Panason : Sterilization of Large Quantities of Water by Ultra-violet Rays, HreLBROoNNER and RECKLING- HAUSEN, 76.—Refrigeration by Mixtures of Liquids, J. Ductaux: The Relations between Chemical Constitution and Some Physical Properties, S. Suites: Positive Rays, W. Wien, 77.—Deflections by Electrostatic and Magnetic Fields of Radium B after Recoil from Radium, A. S. Russ, etc.: Energy Distribution of Diffraction Gratings, A. TRow- BRIDGE and R. W. Woop: Modification in Magnetic Fields of Lines of the Light emitted by the Hlectric Spark, G. A. Hrmsatece: Electric Motors, H. M. Hopart, 78. Geology and Natural History—Grundziige der Paldontologie, K. A. v. ZirreL, 78.—Notes on Ordovician Trilobites, 11, Ill and IV, P. HE. Ray- MOND: Preliminary List of the Fauna of the Allegheny and Conemaugh Series in Western Pennsylvania, P. E. RaymMonp: The British Carbonif- erous Orthotetine, I. THomas, 79.—Geological Excursion in the Grand Canyon District, D. W. Jounson: Aufbau des Gebirges in der Umgebung der Strassburger Hiitte an der Scesaplana, W. v. SEIDLITZ: Granites of the Southeastern Atlantic States, T. L. Watson: The Volcanic Rocks of Victoria, E. W. Skrats, 80.—Analcite Rocks, G. W. TyRRELL : Morganite, a Rose-colored Beryl, G. Kunz, 81.—Tables for the Determination of Minerals by Physical Properties : The Subantarctic Islands of New Zea- land ; British Nudibranchiate Mollusca, with Figures of the Species ; Part viii, Supplementary, 82.—Medusae of the World, A. G. Mayzr: An Introduction to Zoology, R. W. Heener, 83.—Animal Study: with Directions for Laboratory and Field Work, W. H. D. Murer: Methods of Attracting Birds, G. H. TRarton: Second Report on the Hymeniales of Connecticut, EH. A. Waite, 84. iv CONTENTS. Number 182. Page Arr. X.—Adjustment for the Plane Grating Similar to Rowland’s Method for the Concave Grating ; by C. Barus and M,(BAmugieeesse peso. lon). eee 85 XI.—Determination of the Hardness of Minerals, II; by bc Way A Gu ee ees ce ey 1g Ae Yee gen 96 XII.—Photographing Fossils by Reflected Light ; by L. D. Buntang Johan NG itches ae 99 XIII.—Synthesis of the Paleogeography of North America ; ; by -E. Swass 222.3. Sees ee ee 101 XIV.—Estimation of Silver by Electro-Deposition from an Ammoniacal Solution of the Oxalate; by F. A. Gooca and Jo PS Winisnr 2k ee) See ee eee a eS ne 109 XV.—Notes on the Armored Dinosauria; by G. R. WiELAND 112 ie Manne Gneissoid Structure in the Cortlandt Series ; Dy Guts ROG WR hg peter ones ay etn ane es Men 125 XVII.—Thaumasite from Beaver County, Utah; by B. S. Bouriur and- W.."PAScHAmiEME 2205 eee ten eer e 131 XVIII.—Nomenclature of the Lower Paleozoic Rocks of New) York. byiH. PCusnine 2-95. 952- = 2 eee 135 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Determination of Copper as Sulphate, Rrcoura : New Method for Determining Boiling Points and Vapor Pressures, SMITH and Menzies, 146.— Reactions of Nascent Hydrogen in the Dry Condition, Vournassos: Synthetic Sapphire, Verneutnt, 147.—Influence of Tem- perature on the Compressibility of Metals, E. GRUNEISEN : Ionization of the Atmosphere due to Radio-active Matter, A. S. Eve: Thomson Effect, P. Cermak: Velocity Measurement of Rontgen Rays, E. Marx, 148. Geology—Osteology of Pteranodon, G. F. Eaton, 148.—The Age of Mam- mals, H. F. Osporn, 150. —Tertiary Faunal Horizons in the Wind River Basin, Wyoming, with Descriptions of New Eocene Mammals, W. GRANGER, 151.—Geological Survey of New Jersey, Annual Report of the State Geologist, H. B. Ktmuet, 182. Astronomy—Transactions of the Astronomical Observatory of Yale Uni- versity, 152.—Determination of the Solar Parallax from photographs of Eros, 153.—Les Déterminations des Longitudes et l’Histoire des Chro- nométres, J. Mascart: Project for the Reform of the Calendar, C. A. Hesse, 154. Miscellaneous Scientific Intelligence—Report ot the Secretary of the Smith- sonian Institution, 155.—Report of the Librarian of Congress and Report of the Superintendent of the Library Buildings and Grounds : Academic and Industrial Efficiency, M. L. Cooxes, 156. CONTENTS. Vv Number 183. Page Art. XIX.—Transmission of Light through Transparent Inactive Crystal Plates, with Special Reference to Observations in Convergent Polarized Light ; by F. E. WitiGht? 3... 2a9e See See Se ere Eee aera 157 XX.—Separation and Estimation of Barium Associated with Calcium and Magnesium, by the Action of Acetyl Chlo- ride in Acetone Upon the Mixed Chlorides ; by F. A. Gooner andeCr NisBOWNTON 6-2 5-5 so ce one secs =n 212 XXI.—Feldspar Aggregate Occurring in Nelson Co., Vir- Pinay Me WetORNTON,, Iie J o22 2 epen yee aie ee 218 XXII.—History of the Coconut Palm in America; by O. F. (CO CHE o e eee, ee e XXIII.—New Mink from the Shell Heaps of Maine ; by F. booming: 2o5 see ange i aie ie eee reset Mena epee 2247 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Mesothorium, W. MarckwaLp, 230.—Combustion of Hydrocarbons, W. A. Bonn: Supposed Chemical Distinction between Orthoclase and Microcline, VARNADSKY and REvouTsKY, 231.—Preparation of Argon, G. CLaupE: Die Stellung der neueren Physik zur mechanischen Naturanschauung, M. Puanck: History of the Cavendish Laboratory, 1871-1910, 232.—The Principles and Methods of Geometrical Optics, J. P. C. SouTHALL, 233.—Chemische Krystallographie, P. Groru, 2384. Geology and Natural History.—United States Geological Survey, 234.—Pub- lications of the U. S. Geological Survey, 235.—Bureau of Mines, J. A. Hotmes : Florida State Geological Survey, 236.—The Badland Formations of the Black Hills Region, C. C. O’Harra: West Virginia Geological Sur- vey, I. ©. WurtE: New Zealand Geological Survey, 237.—Geological Survey of Western Australia, 238.—Palzontological Contributions to the Geology of Western Australia, 239.—Report of the Vermont State Geolo- gist for 1909-1910, G. H. Perkins: Contribution to the Geologic History of the Floridian Plateau, T. W. VAUGHAN: Recent Discoveries Bearing on the Antiquity of Man in Hurope, G. G. MacCurpy, 240.—Fossil Faunas of St. Helen’s Breccias, H. S. Wintiams, 241.—Palzontologia Universalis, 242.—Botanische Tropenreise, Indo-Malayische Vegetationsbilder und Reiseskizzen, G. HABERLANDT: Plant Anatomy, W.C. Strvens: A. Text- Book of Botany and Pharmacognosy, H. Krammrr, 243.—Biology, general and medical, J. McFaruanp, 244. Miscellaneous Scientific Intelligence—Carnegie Institution of Washington _ Year-Book, No, 9, 1910, 244.—Publications of the Carnegie Institution, 245.—Annual Report of the Board of Regents of the Smithsonian Institu- tion, 246.—Publications of the Allegheny Observatory of the University of Pittsburgh, F. Scauesincer: Bref och Skrifvelser af och till Carl von Linné; Seismological Society of America, 247.—Das Hlectrokardiogramm des gesunden und kranken Menschen, F. Kraus und G. Niconar: Plane Trigonometry, E. R. RopBins : Shop Problems in Mathematics: Ostwald’s Klassiker der Exakten Wissenschaften, 248. Obituary—Sir FRANcIs Gatton; Dr. M. WitnELM Mrynr, 248. yi CONTENTS. ' Number 184. Page Art. XXIV.—Ionization of Different Gases by the Alpha Particles from Polonium and the Relative Amounts of Energy Required to Produce an Ion; by T. 8. Taytor 249 XXV.—Heat Generated by Radio-active Substances ; by W. DUANE 2. 502. 23 ie XXVI.—Contributions to the Geology of New Hampshire, IV. Geology of Tripyramid Mountain; by L: V. IPTRSSON ANG Vint. INFO er chai CL een ee 269 XXVII.—Note on a Method in Teaching Optical Mineralogy; by FW... McN Are Se ne em XXVIII.—New Paleozoic Insects from the Vicinity of Mazon Creek, Illinois ; by A. HanpirrscH---- .------- 297 XXIX.—Results of a Preliminary Study of the so-called Kenai Blora of Alaskac iby Aviioumcnemeee es. == anes 327 SCIENTIFIC INTELLIGENCE: Chemistry and Physics—Use of Calcium Carbide for the Determination of Moisture, Masson : Action of Water upon Phosphorus Pentoxide, BaLa- REFF, 351.—Fractional Crystallization of Argon, F. Fiscurer and VY. FROBOXKSE: Qualitative Chemical Analysis, BASKERVILLE and CURTMAN : Die Verwertung des Luftstickstofts, J. ZenNEcK, 332.—Allen’s Commercial Organic Analysis: Absorption Spectra of Solutions, H. C. Jonrs and W. W. Strone, 333. Geology and Mineralogy—Thirty-fourth Annual Report Department of . Geology and Natural Resources, Indiana, 333.—West Virginia Geological Survey, Vol. 5, Forestry Wood Industries, A. B. Brooxs : Geological Sur- vey of Tennessee; Atlas Phographique des Formes du Relief Terrestre, 334.—Illinois Oil Fields in 1910: Physical Notes on Meteor Crater, Ari- zona, 335.—Minéralogie de la France et de ses Colonies: Practical Min- eralcogy Simplified for Mining Students, Miners and Prospectors, J. P. Rowe: Calcites of New York, H. P. Wurttock: Minéraux des Pegmatites des Environs d’Antsirabé a Madagascar, L. Duparc, 337.—Production of Phosphate Rock in Florida during 1910: North Carolina Geological and Economic Survey, 338.—Note on the parietal crest of Centrosaurus apertus ’ and a proposed new name for Stereocephalus tutus, L. M. Lames, 339. Miscellaneous Scientific Intelligence—Carnegie Foundation for the Advance- ment of Teaching, 339.—Text-Book of General Bacteriology, EH. O. JoRDAN: Catalogue of the Lepidoptera Phalenz in the British Museum, G, F. . Hampson, 340. es Obituary—H. P. Bowpircu : J. H. van’t Horr: J. W. BrUaL, 340. CONTENTS. vil Number 185. Page Arr. XXX.—Melting Points of Minerals in the Light of Recent Investigations on the Gas Thermometer; by A. DLeeWaveandpits by SOSMAN 25202. seen 2S s'Le oss ae 2 341 XXXI.—Separation of Cerium by Potassium Permanganate ; ange imtebe bn OUST Se ete 2(2 7. cle oe can wien Se 350 XXXII.—New Paleozoic Insects from the Vicinity of Mazon Creek, lilimois:;by A. HANDIIRSCH 525)... 22-2 22.2254 358 XXXIII.—New Family of Reptiles from the Permian of INewnMexicaGiby S) Wee WiILLISTON, 2222 55).222 205508 378 XX XIV.—New Elasmobranchs from Solenhofen in the Car- negie Museum ; by C. R. Hastwan. (With Plates I-III) 399 XXXV.—Contributions to the Geology of New Hampshire, No. V ; Petrography of Tripyramid Mountain ; by L. V. IPATESSIORN regener cs cls Soe ee a | 405 XXXVII—Geologic and Petrographic Notes on the Region about Caicara, Venezuela; by T. A. BeNDRAT..------- 443 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Researches on Polonium, Mdme. Currie and A. DEBIERNE, 453.—Introduction to General Chemistry, J. T. Sropparp: Die Beziehungen zwischen Farbe und Konstitution bei organischen Verbin- dungen, H. Lay, 454.—Rays of Positive Electricity, J. J. Thomson, 455.— Focal Isolation of Long Heat-Waves, RuBprns and Woop, 456.—A Method of Calibrating Fine Capillary Tubes, T. R. Merron, 457.—An Intro- duction to Thermodynamics for Engineering Students, Jonn Mints, 468. Geology and Mineralogy—Denudation and Hrosion in the Southern Appa- lachian Region, L. C. Giunn, 458.—Preliminary Notes on the ‘‘ Chazy” Formation in the Vicinity of Ottawa, P. E. Raymonp, 459.—Die Fauna der Spiti-Schiefer des Himalaya, ihr geologisches Alter und ihre Weltstellung, VY. Unuic: Beitrage zur Geologie der Baren-Insel, Spitzbergens und des K6nig-Karl-Landes: Historical-Stratigraphical Review of the Silurian of Sweden, Jon. Cor. Mopere, 460.—Geologisch-petrographische Studien in der Patagonischen Cordillera, P. D. QuENSEL, 461.—Ueber einigige Japan- ische Vulkane, I. FRIEDLAENDER: Geological Survey of Ohio, 462.—Ele- ments of Geology, BLACKWELDER and BarRows: A Remarkable Crystal of Beryl, G. F. Kunz: The Mineralogy of Arizona, F. N. Guiip, 463.—Notes on a recent find of Zincite Crystals, A. H. Puriures, 464. Miscellaneous Scientific Intelligence—National Academy of Sciences, 465.— Bulletin of the Seismological Society of America, 466.—Commercial Geography, E. V. Ropinson, 467. Obituary—S. F. Emmons, 467: S. Catvin: J. M. Van BeMMELEN: Mrs. EK. H. Ricnarps: HE. E. Hows, 468. Vili _ CONTENTS. Number 186. ; . Page Art. XXXVIII.—Podokesaurus holyokensis, a New Dino- saur from the Triassic of the Connecticut Valley ; by M. Parson, (With Plate GV.) e222 22k 469 XXXIX.—Minerals Associated with Diamonds and Carbon- ados in the State of Bahia, Brazil ; by J. C. Branner.. 480 XL.—An Engelhardtia from the American Eocene; by E.. W.. BER By ee RE Re oo geet en 8 cha 491 XLI.—Use of Sodium Paratungstate in the Determination of Carbon Dioxide in Carbonates and Nitrogen Pent- oxide in Nitrates ; by F. A. Goocu and 8. B. Kuzirian 497 XLII.—Influence of Pressure on the Melting Points of Certain Metals; by J. Jonnsron and L. H. Apams ..-- 501 XLIII.—A New Occurrence of Pearceite; by F. B. Van Horniand Cx WicCoom a2 5. caer cee ae XLIV.—Mollugo verticillata L.; by T. Horm .--.---.---- 525 XLV.—Composition and Crystallization of Parisite and Occurrence in the Granite-Pegmatites at Quincy, Mass., - U.S. A,, etc., by C. Panacue and C, H. Warren ----- 538 XLVI.—Notes on the Absence of a Soil Bed at the Base of the Pennsylvanian of Southern Ohio ; by J. E. Hype __ 557 ' XLVII—A New Jolly Balance; by E. H. Kraus -----.--- 561 XLVIII.—Independence of the Coronas of the Thickness of the Woe Waiver, siloyg, @. gly AS seat eee eee 564 SCIENTIFIC INTELLIGENCE. Chemistry and Physics.—Radium Contents of some Uranium Minerals, MarckwaLp and RvussELL, 566.—Determination of Cane Sugar in the ~ presence of other Sugars, A. Jottes: Action of Sulphur Dioxide upon Ammonia, EPpHRam and ProrRowskt, 567.—Quantitative Chemical Analy- sis of Mixtures, H. FRIEDENTHAL: Metallic Coloring in Birds and Insects, A. A. MicHELson, 568.—Isolation of an Ion, a Precision Meas- urement of its Charge, and the correction of Stokes Law, R. A. MILLIKAN, 5970.—Homogeneous Rontgen Radiation from Vapors, J. C. CHAPMAN, 571.—Lehrbuch der Kristallphysik, W. Voter, 572.—Electrical Nature of Matter and Radioactivity, H. C. Jones, 573. Geology and Mineralogy.—Illinois State Geological Survey: New Zealand Geological Survey, 573.—Geological Survey of Western Australia: Geo- logical Survey of Canada, 574.—Mineral Production in the United States in 1909, 575.—Production of Gems and Precious Stones in 1909 : Production of Bauxite in 1909: Origin of the Thermal Waters in the Yellowstone National Park, 576.—Tables for the Determination of Minerals, H. H. Kraus and W. F. Hunt: Striiverite, R. C. WELxs, 577. Miscellaneous Scientific Intelligence.—Bulletin of the Bureau of Standards : Prehistoric Period in South Africa, J. P..Jonunson, 578.—Field Museum of Natural History : Astronomical and Astrophysical Society of America, 580.—Harvard College Observatory : Cincinnati Observatory: Princeton University Observatory: R. Comitato Talassografico Italiano, 581.—Con- gress of the Applications of Electricity : Congress of Applied Chemistry : Anthropological Society : University of Bologna, 582. Obituary.—SAMUEL H. ScuppER; M. Epovarp Dupont: THomMas RUPERT Jones ; J. Bosscwa, 582. InDEx TO VOLUME XXXII, 583. > 7 ‘f VOL. XXXI. JANUARY, 1911. Established by BENJAMIN SILLIMAN in 1818. HT AMERICAN JOURNAL OF SCIENCE. Epiror: EDWARD S. DANA. — \ ASSOCIATE EDITORS Proressors GEORGE L. GOODALE, JOHN TROWBRIDGE, W. G. FARLOW ann WM: M. DAVIS,: or CampBrince, Proressorns ADDISON EB. VERRILL, HORACE L. WELLS, L. V. PIRSSON anp H. E. GREGORY, or New Haven, Proressor HENRY S. WILLIAMS, or Irwaca, Proressorn JOSEPH S. AMES, oF Bartimmore, Mr. J. S. DILLER, or Wasuinerton. FOURTH SERIES VOL. XXXI—[WHOLE NUMBER, CLXXXIJ]_ No. 181—JANUARY, 1911.9" : NEW HAVEN, CONNECTICUT. dL Oalsk THE TUTTLE, MOREHOUSE & TAYLOR ©O., PRINTERS, 123 TEMPLE STREET. Published monthly. Six dollars per year, in advance. $6.40 to countries in the either by money orders, Postal Union ; $6.25 to Canada. Remittances should be made registered letters, or bank checks (preferably on New York banks). food B ol IMPORTANT TO MINERATLOGISTS. I have the pleasure to inform my numerous patrons that I have just secured:a collection of remarkable old finds from exhausted localities, which was collected by a well-known mineralogist. This collection represents some of the finest crystallized minerals from well-known American localities some of which are not at present procurable. This collection will be placed on sale by January 15th. Full details of special list sent on request. I can safely state that no dealer has ever had at one time as many Zincites crystallized as there are in my present stock, at prices which will tempt any: collector not having these remarkable rare crystals ; also a good stock of all the well known Franklin Furnace minerals. COPPER AND SILVER FROM LAKE SUPERIOR. I have just received a large lot of excellent crystallized Silver and also Copper, Calcite enclosing Copper, Psilomelane, etc., in large and small sizes at very reasonable prices. COLORADO MINERALS. Recent additions to my already large stock of Colorado Minerals include the following: Native Tellurium, Sylvanite, Calaverite, Gold Pseudomorph, Smoky Quartz Crystals, Amazonite Crystals, Topaz, Aquamarine, Calciovol- borthite, Crystallized Carnotite, Pyrite, Rhodochrosite, Fluorite. CALIFORNIA MINERALS. In addition to my already large stock of California Tourmalines, I have made special connections with one of the large mining concerns for all their specimens and I have just received as fine an assortment as ever was found, all ranges of quality and color, at reasonable prices. Tam making special efforts in my gem department to supply Gem collec- tors with rare stones in all sizes, shapes and colors. I have also added considerably to my stock of Reconstructed Gems and have the following to offer :. Rubies, sapphires, blue, yellow, pink and white ; in all sizes and shapes of the best quality. If you are interested in anything in Mineralogy send for my special lists or request me to send you a ship- ment for your selection, prepaid. Do not fail to send your name for my mailing list, mentioning AMERICAN JouRNAL OF SCIENCE. A. H. PETEREIT, 81—83 Fulton Street, New York City. 4 DS Oto) AMERICAN JOURNAL OF SCIENCE [FOURTH SERIES. ] Arr. I. — On Gravity Determinations at Sea;* by L. A. BaveEr. A etven mass changes its weight when transported over the Earth’s surface. How shall we determine these alterations ? It cannot be done with a balance; for a mass in one scale pan held in equilibrium by a set of weights in the other pan will remain in equilibrium all over the Earth, since the Earth’s gravitational force within our limits of measurement acts alike on all substances. The variations in gravity are composed of three parts: one called the ‘normal part,” varying simply with latitude; another the “anomaly,” a more or less irregularly distributed part, and the third part dependent upon altitude of station above sea-level. We might replace the beam of our balance by a pivoted magnetized steel bar or needle. Suppose we were to start out _ from Washington, where the magnetic dip is about 70°5°, with the beam made to le horizontal by suspending a suitable weight on its south end; we have thus balanced the earth’s gravitational force by the vertical component of the Earth’s magnetic force. Were we now to proceed with this balance to some distant point, the beam might no longer be truly hori- zontal but make instead an angle with the horizon, the magni- tude of which would depend upon the relation at that point between the earth’s magnetic and its gravitational force. Knowing the value of the vertical magnetic component, it is then possible to determine, within certain limits, from the inclination of the beam how much the suspended mass has i Presented before the Philosophical Society of Washington, November 5, 0. Am. Jour. Sci.—FourtH Series, Vou. XXXI, No. 181.—January, 1911. 2 L. A. Bauer—Gravity Determinations at Sea. altered its weight, or in turn find the change in gravitational force. We have in fact such an instrument as here described, viz., the dip circle used in determining the total magnetic force by Lloyd’ s method, one operation consisting of measuring the angle of dip of a suspended magnetic needle having a load on one end. Observations made thus on the ‘ Galilee” in the Pacific Ocean, covering a range in latitude from about 59° North to 42° South, showed that the variation in weight of the load over a large range in latitude might be taken into account. With such a dip circle, the latitude variation of gravity could just about be detected ; however, for smaller gravity variations the instrument would not be sensitive enough, both because of its construction and our inability to determine the magnetic force with sufficient precision. The method most commonly in use on land for determining the value of the linear acceleration of gravity, g, is by pendu- lum observations. But this method has not been found feasi- ble on board ship. If, then, it is desired to extend a gravity survey so as to include the oceans as well as the land, other experimental means than swinging pendulums must be devised. The method thus far used to disclose gravity anomalies at sea is that known as the “boiling point, mercurial barometer method.” The principle here is to measure the counterbalane- ing effect of the elastic pressure of a vapor on a column of mer- cur y, once by reading the height of the mercurial column, the counterbalancing vapor being the atmosphere ; next, by measur- ing the atmospheric pressure prevailing at the time by deter- mining the temperature ot the boiling point of pure water. Since the boiling point, other things being equal, depends solely upon the atmospheric pressure, it will not vary as we pass over the earth as long as the pressure is the same; how- ever, the height of the mercurial column, under the same con- ditions, changes with variationsin gravity. Hence the gray- ity anomaly is found by a direct comparison of the atmospheric pressure determined from the boilmg point with that read off on the mercurial barometer. Prior to the boiling-point method for measuring the prevailing atmospheric pressure inde- pendently of gravitational force, the use of the aneroid was proposed ; however, the latter instrument is found too variable and uncertain in its indications to possess the required sensi- tiveness. Guillaume in 1894 was led to suggest the use of boiling point thermometers in place of the aneroid, but Mohn* has the credit of having made the first practical use of the method, * Mohn, H.: Das Hypsometer als Luftdruckmesser und seine Anwendung zur Bestimmung der Schwerekorrektion. Christiania, Skr. Vid. Selsk. Math.-naturw. K1. I, 1899, No. 2 (1-69). L. A. Bauer—Gravity Determinations at Sea. 3 in determining between 1896 and 1898 the gravity correction to observed barometric heights at various stations of the Mete- orological Service in Norway. It was Mohn’s suecess which led Helmert and Hecker to consider this method for ocean gravity observations. Hecker, working under the direction of Helmert, has thus far made three expeditions, chiefly at the expense of the Inter- national Geodetic Association,—the first in 1901, in the Atlan- tic from Hamburg to Rio de Janeiro and return to Lisbon ; next in 1904, a eruise extending over the Indian and Pacific Oceans, and finally in 1909 in the Black Sea. All of his work was executed in a most painstaking manner and a very elabo- rate instrumental outfit was used; the observations were made only on good-sized steamers of 5000 tons and upward. In his Black Sea eruise, of which the results have just appeared, the Russian cruiser “ Pruth,” of 5500 registered tonnage, was put at his disposal; his instrumental outfit consisted of six boiling point apparatuses, each provided with a thermometer and two sets of photographically registering barometers, one set having five mercurial barometers and the other four, or nine specially constructed barometers in all. The thermometers were read with a telescope magnifying twenty times, so that to the observer 0°001° appeared of the length 0-4". The nine photo-baro- grams were independently read by two assistants and correc- tions for various sources of error were applied. Hecker also devised instruments for photographically recording the ship’s motions, with the aid of which further corrections were deter- mined. Finally, an elaborate adjustment by the method of least squares was made of the outstanding differences between the atmospheric pressure, A, derived from the boiling point work, and that, 6, resulting from the barometric readings referred to standard temperature and normal gravity for lati- tude 45°; there were thus determined further corrections, as explained later in this paper. The 1901 work was published in 1903, that of 1904 in 1908, and that of 1909 in 1910. In Hecker’s last publication are given, in addition to the Black Sea results, the revised results of the work done in 1901 and 1904, so that the previous publi- cations are superseded by this latest one. The revisions were made necessary by the correction pointed out by Baron Kétvos due to course and speed of vessel. Hecker’s work in the Black Sea was done partly for the very purpose of testing whether his methods were of sufficient accuracy to detect this theoretical correction; he reaches an affirmative conclusion and, accordingly, revises his previous reductions. He now also. excludes, in the least-square adjustments, observations in ports 4 L. A. Bauer—Gravity Determinations at Sea. made on vessel at anchor; his present results for Ag differ at times from the previously published ones by 0°15°™, Suggestions have been received from various sources that it would be highly desirable to include, if possible, gravity work on the “Carnegie.” At the request of President Woodward, I consulted in 1905 Professor Helmert, Director of the Geo- detic Institute at Potsdam, as to the possibility of attempting the boiling-point method on the “Galilee,” which had just been chartered for magnetic work in the Pacific Ocean. As the result of Hecker’s experiences on vessels exceeding the ton- nage of the “Galilee” by eight times and more, Helmert did not feel warranted in advising the undertaking of similar work on our vessel; he thought it best under all circumstances to await the conclusion of Hecker’s labors. No attempt was accordingly made on the ‘ Galilee.” However, on the “Carnegie” it was decided to include determinations of the temperature of the boiling point of water in the regular routine work aboard, the prime purpose being to obtain data for controlling the corrections of our ane- roids. The instrumental equipment was in accordance with this aim; it consisted merely of two boiling apparatuses of the pattern described and figured in the British Antarctic Manual of 1901, p. 94, two specially constructed thermometers by Green, of Brooklyn, N. Y., graduated into one-hundredths of a degree centigrade from 97°6° to 107-7°, the length of one degree being about 40 millimeters, and one Green mercurial marine barometer. In all 106 determinations of the boiling point were secured on the First Cruise, between Sept. 1909 and Feb. 1910, four of which had to be rejected because of manifest errors, leaving 102 values and representing 75 differ- ent points. While a few observations were made at the very beginning of the cruise, by Mr. J. P. Ault, the navigating officer, the work did not begin regularly until the vessel left Falmouth on November 6, 1909, but thereafter to Madeira, thence to parallel 20° North and return to Brooklyn via Ber- muda, the observations were made almost daily by Dr. C. C. Craft, and that too at times under very trying conditions of weather. A week’s series or more was obtained at each of the ports,—Brooklyn, Falmouth, Funchal (Madeira), and Hamilton (Bermuda). The two boiling-point thermometers were read visually, with the aid of a hand lens, to the nearest 0:001° by estimation of a tenth of a space 0°4"" long; and the mercurial barometer was read directly by vernier to 0-01 inch and by estimation to 0-005 inch or less. The pumping of the barometer, which is of the ordinary marine type, amounted at times under the severe conditions of sea encountered on the return trips to as much as LI. A. Bauer—Gravity Determinations at Sea. 5 5™™; several settings were made, and both the low and high readings were recorded. To reduce the pumping, Hecker had introduced a special capillary tube in about the middle part of his barometer, and, since his observations were made on large steamers, the pumping of his barometer was generally less than 075". A eareful scrutiny of our observations has encouraged me in the belief that it may be worth while to attempt also gravity work on the “ Carnegie,” which in her various cruises will have opportunity of getting data in regions not yet coy- ered, and will also at times cut across Hecker’s trips. Atten- tion is accordingly being given to the question of refining the instrumental appliances and simplifying the method of reduc- tions. As the best preparation it was thought well to review carefully Hecker’s work in order that full advantage might be taken of his experiences in this pioneer work, as also to determine what were the various sources of error and their rela- tive importance. (Cf. Bestimmung der Schwerkraft auf dem Schwarzen Meere, etc., Berlin, 1910.) Hecker’s Ocean Gravity Observations. Let us begin with the formule used, and the theoretical treatment applied to the observations. Let A=atmospheric pressure deduced from the temperature of the boiling point of pure water with the aid of tables, as for example Wiebe’s, given in the “ Landolt—Boérn- stein Tabellen” for 1905 ; £=the simultaneously observed atmospheric pressure with a mercurial barometer, reduced to standard temper- ature, to sea-level and to normal gravity for latitude, p=4o° ; thenis @= A— Binmms. mercury. (1) Were there no errors of whatever kind attaching to A or B, then 8 would be the gravity anomaly sought. To convert into ems. of the acceleration of gravity, g, we must multiply equation (1) by the approximate factor, 980/760 = 1:29, hence Ag = 1:29 (A — B) in ems. per second. (2) The reduction of & to normal gravity is made with the aid of Helmert’s formula of 1901* : ¢ = ( — 0002644 cos 26 + 0:000007 cos’ 26) B. (3) The coefficient of the second term was adopted by Helmert from the theoretical investigations of Wiechert and Darwin; * See note next page. 6 L. A. Bauer—Gravity Determinations at Sea, however, the first coefficient, 0:002644, he deduced empirically* from a least-square discussion of nearly one-fourth of the available pendulum observations, selecting undisturbed coast and inland stations. This first coetticient gives for the ellip- ticity of the earth, 1/2983; the value adopted in the Smithsonian Meteorological Tables, 1907, is 0°002662 as obtained by Professor Harkness in his work “The Solar Parallax and its Related Constants, Washington, 1901.” For B = 760, for example, the first corrective term for a point on the equator would be, —2-0095™™"s for Helmert’s formula and —2-0231°™S for the Smithsonian Tables; the second term for 6 = 760™™ and the equator amounts to +0:0053, so that the total correction, according to Helmert, would be —2°0042"™"*. For the poles, the corrections would be, +2°0095 and +2°0231™™s. In order, therefore, to detect by ocean observations the difference between the two formule, it would be necessary to secure an accuracy of about 0:01™ mercury or 0:015"™ acceleration or about 1/100,000 part of g. This matter is mentioned here since one of the conclusions drawn by Hecker from his ocean observations is that they accord with Helmert’s formula, But A and & are subject to various sources of error, partly due to instrumental causes and observational errors and partly due to motion of the vessel. Of the disturbances caused by the vessel there are two which may readily be disposed of. First that due to tbe possible attractive effect of the mass of the vessel, since this even for a 100,000 ton vessel would only be on the order of 1/1,000,000 of g, is negligible; second, that due to the course and speed of the vessel. Only the motion in longitude counts—for a vessel sailing east along a certain par allel the instruments aboard are being transpor ‘ted around the axis of rotation of the Earth faster than is a fixed point in the same parallel and the force of gravity aboard is accord- ingly diminished and the mercury in the barometer made to stand correspondingly higher than it would were the vessel not moving. For a vessel sailing west, the effect is reversed. So that if at a certain point on the earth gravity is measured aboard a moving vehicle, once when moving eastwardly and next moving westwardly at the same rate of speed, the values of g at the two times would differ by twice an error, the exact amount of which may be computed from the following formula : *Helmert, F. R. Der normale Theil der Schwerkraft im Meeresniveau. Sitzber. Akad. Wiss., Berlin, xiv, 1901. There is a misprint in Hecker’s publication of 1908; at top of. table, p. 226, Helmert’s coefficient is given as 0:00244 instead of 0°002644. ih al LI. A. Bauer—Gravity Determinations at Sea. 7 Let c’ = correction to an observed mercurial barometric height on account of speed and course of moving vessel, C= velocity of a point in the equator = 4:65 x 10° em. / see. y= “ * ship along a parallel of latitude. FR = earth’s mean radius — 6°38 X 10° em. then is Fa UOON AO rime. sane tec Ly Eau vind — 980 Bi s' 6=0'0146 cos’ ¢ inmm.mereury (4) — for vessel going east. + for vessel going west. To get the correction in ems. g, multiply the tabular quan- tities by 1:29. For a oe sailing east, for example, along the equator at. the rate of 7 degrees or 420 knots a day, the atmospheric pressure sheerved on board with a mercurial bar- ometer would have to be diminished by 0°:1™™. On the other hand, for the same vessel going west at the same speed, the barometer reading would have to be increased Oy Wee Lie the first case g would be too low by 0°15°" and im the second too high by the same amount, or the resulting error, if not taken into accouat between the two occasions, would be 0:30 or 1/3300 part of g—a respectable quantity. "On the aver age, Hecker’s corrections for the vessels on which he made his observations was about + 007°" in g; for the “ Carnegie ” the correction would usualiy be less than + 9°03. Since the cor- rection is a perfectly definite one and can readily be coniputed, it is worth while applying. But there are more troublesome sources of disturbance arising from a moving vessel not so readily disposed of as the preceding one—arising from the actual motions of the vessel, such as rolling and yawing, vibration due to machinery, and worst of all, pitching and accompanying vertical motions. Hecker, as above stated, undertook to determine these sources of error instrumentally with the aid of devices recording the ship’s motions. He then determined the reducing coefficients for each effect by a least-square adjustment of all the observa- tions made on any one cruise. The manner of mounting, as compared with those of the barometers, as well as an examina- tion of the results of Hecker’s laborious least-square adjust- ments, leads one to question the effectiveness of his devices for the elimination of the ship’s effects. Next are the errors due to purely instrumental causes, such as changes in the corrections of the thermometers with which the boiling point of pure water is determined, furthermore the relation of the zero of the boiling-point atmospheric pressure to that of the mereury barometer, and the variations in this relation, etc., ete. 8 L. A. Bauer—Gravity Determinations at Sea. Hecker’s final observation equation is of the following form : d B B+k,+a ae +bp+er+ds+e(t—t,) +h,=0. (5) I have substituted 8 for his quantity (Therm. —. Bar. — com- puted gravity reduction to 45° — correction due to speed and course of vessel); it is the same as the quantity in equation (1) after having had the correction ¢’ applied to B. k,, = relation of the two zeros above + constant part of other corrections. ad B ag bee correction to reduce the observations of boiling Me poimt and readings of barometer to same moment of time for any one set. bp = correction due to pumping, p, of barometer. cr = 6 “« © rolling of vessel. ds — ce oe 66 pitching oe 66 e(t—t,) = ue «“ “ time changes in instruments supposed to progress linearly. k, = constant which enters into the equation only for deep sea observations, say for depths beginning with about 2000 meters. There are thus in Hecker’s complete equation seven unknowns, kn, a, 6, c, d, e, and &,, which he determines by the method of least squares. Substituting next in each observation equation, of which there is one for each station, the derived values of the unknowns, a residual quantity, v, is obtained, supposed to be the gravity anomaly sought. To get a clear understanding as to the assumption implied in his formula, let us suppose first that all the corrective terms in (5) except k, and #,, by a suitable scheme of observation and in a calm sea, reduce to negligible quantities, then we have for a shallow water station, s, 8, = — = constant, (6) and for a deep water station, d, Ba= —k, — k, = constant, (7) or 8, — Bag =k, = constant. (8) The same result (8) is obtained if we suppose, in passing from s to d, the corrective terms for each station were the same in magnitude and sign. But the difference @s—d, under the conditions supposed, when multiplied by 1-29 (see equation 2) should be the difference in Ag at the two points, ’ which of course would not, in general, be a constant. In other L. A. Bauer —Gravity Determinations at Sea. 9 words f is composed of two distinct quantities, one, Ay, repre- senting the gravity anomaly and the other the various sources of error, 2, “and so we have: Ag mag. Ag Oe > 09 oe (9) Comparing this equation with Hecker’s (5), it must be evi- dent that his corrective terms include the effects of the very quantities—the Ag’s—to be determined. Since he applies the method of least squares to his equation, Hecker must asswme that during a cruise the local gravit y anomalies, 1.¢., the Ag’s, partake of the nature of accidental errors—that they either balance out in the long run or oscillate about a mean constant value, which enters into the constant terms of (5). But is not the proving whether such distributions of gravity anomalies exist, or do not exist, the very purpose of gravity surveys ¢ Furthermore, since Hecker adjusts each cruise by itself, then by the theory of least squares alone, the sum of his residuals or outstanding gravity anomalies must reduce to zero, or prac- tically so, because of the presence of the constaut terms in (5); hence his average computed § tor the cruise must be ¢heoreti- cally equal to his average observed 8, or in other words, the average gravity anomaly of @ whole cruise would be zero. It must be evident then that as Hecker derives his unknowns they are not true values but are affected by the gravity anomalies over the areas for which the adjustment is made. They might be different, for example, for a cruise from New York to Liverpool than for one from Hamburg to Rio de Janeiro, even - though all conditions remained precisely the same except that of difference in route followed. Manifestly then Hecker’s method of adjustment is open to grave objections and it is a question as to how much of his resulting conclusions may not already be contained in his fundamental assumptions. Let us hope that the variations in the gravity anomalies at sea about an average value will be found to be of asufficiently accidental nature to vitiate Hecker’s main conclusions! Strictly speaking, the values of the unknowns entering into equation (5) can only be derived from stations where “there exist accurate gravity observations from which the anomaly Ag can be derived. This means, however, restriction to shore and harbor observation, but these are the very observations which above all Hecker has been unable to reduce satisfactorily 10. LL. A. Bauer—Gravity Determinations at Sea. and hence either omits entirely in his final tables or brackets as doubtful. In the first place the coefficients, 6, c and d, can of course only be found from observation on a moving vessel. How poorly the Ag’s from the harbor observations agree, in general, with those resulting from shore pendulum observations when the former are computed with the values of the unknowns obtained from the observations on the moving vessel, is shown by a table which Hecker gives on p. 159 of his 1910 publica- tion. The differences amount at times to 1/6000 part of g. Hecker believes that the trouble arises chiefly from the fact that observations on a vessel moving and on one at rest are not comparable and, hence, require separate treatment, the difference arising chiefly from the dynamic conditions which enter in on the moving vessel. While he is undoubtedly in the main correct, still he does not appear to see that the un- knowns as he derives them are not strictly instrumental or ship constants, but depend, as has been shown above, upon the area (extent and geographic position) from which they are derived. In any case, beyond revealing the discrepancies, he does not make known any attempt at a satisfactory reduction of the harbor observations. This is doubly unfortunate, first, because the harbor observations ought to furnish the best criteria pos- sible of the absolute accuracy and possibilities of his method of observation, and secondly, since the connection of ocean results with land stations is correspondingly diminished in strength. Every series of observations made by Hecker on shore or in port has been investigated, and not a single case of satisfactory reduction or adjustment was found. On his first eruise in 1901, in the Atlantic Ocean, from Hamburg to Rio de Janeiro and return to Lisbon, he made shore boiling-point observations at Rio de Janeiro and Lisbon at precisely the same places where he swung his pendulums. There was thus afforded a fine opportunity to test his boiling-point method and the behavior of his instrumental appliances. But he makes no attempt at such a comparison. Instead, he merely adjusts the series of shore observations at Rio de Janeiro o, Aug. 24—-Sept. 11, 1901, by itself and similarly the series at Lisbon, Oct. 12-17, 1901, again by itself. His observation equation is the same as (5) above with the omission of the terms involving J, ¢, d, and &,, which apply only to observations at sea. While his adjustment improves the ¢ndividual day’s results at each of the two stations, it leaves unaltered the actual mean gravity anomaly observed at each station—in brief, he does not adjust Rio de Janeiro and Lisbon together, and the labor of his painstaking adjust- ments is practically. for naught. Hence, if we take the quantities, as derived from Hecker’s adjustments (or from the L. A. Bauer—Gravity Determinations at Sea. 11 direct observations), we may see what the extent of énstru- mental changes may be during even such a brief interval as six weeks, during which, thermometers are subjected to fre- quent and protr acted boiling. The mean Ag results for Rio de Janeiro—Lisbon derived from each of four barometers—two eye-reading ones and two photographically recording ones— differ from the pendulum value by —0-105 to +0: 200°", thus exhibiting a range of 0°3. Even the two visual barometers give results from shore observations differing by 0-1 and this in spite of Hecker’s laborious method of observation. The mean result here considered for any one barometer depended on 24 boiling point determinations and 8 barometric readings times the number of days, or for Rio de Janeiro, 360 B. Pts and 120 readings of each barometer and for Lisbon 216 B. Pts and 72 readings of each barometer ! Hecker made no shore observations by the B. P, method on any of his subsequent cruises, but he made a number in harbors on board vessels at anchor. These also exhibit most marked changes in but a few days, the effects of which if likewise experienced at sea, as must undoubtedly be the case, would exceed in impor tance the corrective terms in equation (5) due to motions of ship. Jn his Black Sea work, Hecker had repeated trouble with his thermometers so as to be obliged to discard some series entirely. The thermometers were made by Fuess of Steglitz of Jena borosilicate glass 59 III. Looking over Hecker’s scheme of observations, the suspicion is awakened that he ‘‘ boiled” too often and too protractedly —a fact he himself began to suspect in his later work. What accuracy was supposed to be gained by excessive observing was lost in resulting instability of his thermometers. he corrections jor Hecker’s thermom- eters were never re-determined after they had once been fur- nished by the German Pha ysihalische Reichsanstalt. Though some of the thermometers had been in use on the three cruises of 1901, 1904 and 1909, practically the same table of thermo- metric corrections is employed throughout. Three of them were provided with zero points but the zeros were never re-determined. Zhe corrections for the various barometers on a standard barometer for various barometric heights were never determined, or it so, they were not used, the observer supposing that all instrumental changes—both of thermometers and of barometers—would fully be taken account of by a con- stant term (#,, equation 5) and by a term, ¢ (¢—7,), progressing linearly with the elapsed time. Let it ‘be remembered that these two quantities #, and e were not derived from observa- tions at stations where Ag was known from pendulum work, but from the discussion of ocean observations for which a fictitious distribution of gravity anomalies had to be assumed in order that a least-square adjustment could be made. 12 L. A. Bauer—Gravity Determinations at Sea. The first point to be made, therefore, on the instrumental side is, that in order to secure desired accuracy in gravity determinations from boiling-point observations, it is essential that a method of observing be adopted which will protect, as nearly as possible, the instruments from changes of whatever kind, and next that the boiling-point thermometers be provided with zero points, the variations of which may be determined in the field with melting ice once a week or as often as may be found necessary. The next point is that the method of observations be such that they can be quickly reduced and that too in such a perfectly definite manner as to admit of no ques- tion with respect to the logical method of reduction to be employed. Hecker, as shown aboye, did not lay sufficient stress upon these vital points. It is believed that equally good, if not indeed superior results, can be obtained with less equipment than used by Hecker, using a simpler method of observation as well as of reduction. Hecker’s cumbersome adjustments at times appear to have caused much needless labor. See, for example, his Black Sea adjustments, where he has attempted to derive his many unknowns from an insufh- cient range of conditions. Another very important point introducing a source of error not considered by Hecker is with regard to the possible errors in the vapor tension tables used to convert boiling-point tem- peratures into corresponding atmospheric pressure. The latest of these tables are those of Wiebe’s given in Landolt-Born- stein’s “Physikaliseh-Chemische Tabellen” for 1905. The most recent observations appear to be those of Holborn and Henning. For the purpose of gravity work, it is essential to be able to obtain accurately the atmospheric pressure for a com- paratively limited range extending below and above 100° C.; the observations on which the tables are based were made at larger intervals and the interpolation is accordingly somewhat uncertain. It is quite possible that the atmospheric pressure as taken from the tables may be out by -05 to 0:1", which corresponds to 0-065 to 0°135™ in g. When dealing with only differential results, as we are in our case, the tabular errors are somewhat eliminated, though not wholly. Zhe problem of most accurate vapor-tension tables for water between 99° and 101° is here called to the attention of physicists. Hechers Gravity Results. From the explanatory statements on p. 150 of his 1910 pub- lication, it is seen that Hecker uses a different plane of refer- ence for the gravity anomalies, the Ag’s, over each ocean, and that the planes refer strictly only to the parts of the respective oceans traversed. No direct comparison can in consequence be made in passing from one ocean to another and il L. A. Bauer— Gravity Determinations at Sea. 18 even for the same ocean, eg., the Atlantic, it would not be possible to compare directly gravity anomalies between New York and Hamburg, with Hecker’s between Hamburg, Rio de Janeiro and Lisbon. He does not explain completely how he actually connected ocean results with pendulum stations; for example, how he. distributed the correction from one land station to another. Why he did not refer his Atlantic Ocean results likewise to his pendulum stations, e.g., at Rio de Janeiro and Lisbon, he does not say. All this confusion has come about because of Hecker’s method of adjustment, as already explained, whereby he discards the shore and port boiling-point observations ab inztio and gets his unknown coefficients from a least-square adjustment of ocean observations. Having done that, he finds that the port observations computed with these coefficients give results not only very discordant among themselves but also with the pendulum observations. He then has the difficult problem of connecting his ocean results with land pendulum stations by means of more or less discordant port and shallow water stations. Tables I and II were drawn up from the figures in Hecker’s 1910 publication ; a plus sign means that g at the place in ques- tion is greater than it would be did the local disturbing cause not exist, and a minus sign means, of course, the reverse. It must be recalled that the tabulated Ay’s are those as derived from Hecker’s adjustments ; if we may assume them correct, a mere glance shows at once that the disturbances in g are, in general, larger over the oceans than usually observed on land. Table I would show that the difference in Ag for two oceanic points may reach 0-4 and even 0°67. TaBLE I.—THE AVERAGE, THE MAXIMUM, AND THE MINIMUM VALUES OF GRAVITY DISTURBANCES AS SHOWN BY H&rCKER’S OCEAN OBSERVATIONS. (Revised figures 1910.) > |oA Ag Route = 168 A |AO|Average |Maxi’um| Mini’um) Range em em em em Hamburg—Rio de Janeiro-___- 1901} 47 | +0-048 | +0:172 | —0:095 | 0-267 Rio de Janeiro—Lisbon ___.__-_ 1901) 35 56 | +0°142 } —0-123 | 0°265 Spain—Suez—Colombo ----.--- 1904) 33 83 | +0°289 | —0°106 | 0°395 Colombo—Sydney -. .____....|1904/ 28 61 | +0°214 | —0-106 | 0°320 Sydney—Honolulu—San Fran- CISCO. =: eee a ee ELS 1904| 41 106 | +0°393 | —0°273 | 0°666 San Francisco—Honolulu—Yo- kohamla SS Sueeaee ese ee 1904) 33 54 | +0°310 | —0-067 | 0°377 Black Sea (Odessa—Batum) ____/1909) 15 31 | +0:079 | —0-052 | 0:131 Entire Work, 1901—1909___. 232 | +0:066 | +0°393 | —0-273 | 0-666 14 L. A. Bauer—Gravity Determinations at Sea. TasLe II.—Some Larce Gravity Distursances Saown By Hecker’s OBSERVATIONS, 1901-1909. mate riser figures 1910.) Cruise \Ye’r| Ag Lat. Long. | Depth Region | em m ° ( | | + 0°172|35° 02’ N) 11°56’ W)| 3600 |Deep sea. ge a ee a )ig01/4 1488 36 S| 34 58 W| 40 [Nea Pernambuco. ; | — 095/11 44 N) 26 59 W) 5600 |Deep sea. ( \— 12311 35 S) 86 49 W) 3200 |Deep 2D) AnD 100 km. or Rio de Janeiro— J 4901 + 123) 6 238 S} 38 20 W) 5000 of move from Bra- Lisbon } |+ °142| 2 15 N| 29 38 Ww! 2000 « \ zilian coast. L + 123) 1 04 N| 30 08 W) 2400 |Near St. Paul. {| + 289/48 34 N) 9 30 E) 200 |Med. Sea, N. of Corsica. | (+ °23512 34 N) 55 45 E) 3400 |Near Socotra. + °214/35 49 N|129 64 E) 5400 |Steep gradient. | + °346/33 49 S/151 54 HE} 200 Bt D f + °393/384 17 S172 07 HE) . 150 |Near N. point N. Zealand. So even i 24 Wig0dl ms pe6di8 20 S178 27? E) 2700 |Tonga Plateau. {| + 161/27 15 S177 40? E| 2700 iN | | — ‘196/23 12 S174 47 E) 8000 |Tonga Deep. | — 273/22 07 S|174 13 | 6500 ui — °245)17 09 S171 42 H 8500 re L + 26821 17 Nj157 50 KE) 20 |Roadstead of Honolulu. San Franciseco— ; 1904) + *310/21 18 N\157 387 E). 70 |Near Oahu. Yokohama + °304/21 17 N\158 17 | 1700 . | + ‘079/44 51 N| 82 46 E) 150 |Shallow water. BLISS ae i 1909)” -052/43 36 NI 35 50 El 2200 ‘Deep water. Table III gives a comparison between Hecker’s 1908 and 1910 values of Ag for certain characteristic points in the Pacific Ocean selected by Prof. J. F. Hayford in his paper before the meeting of the International Geodetic Association of 1909.* The last two columns are the differences between Hecker’s values of g and those computed by Hayford with the aid of his new method; I have myself added the 1910 figures. TasLeE III.—ComMpariIson OF SOME OcEAN GRAVITY ANOMALIES OBSERVED BY HECKER IN THE PACIFIC OCEAN WITH THOSE RESULTING FROM HAYFORD’S COMPUTATIONS. Depth | Hecker’s Ag | Ee Se iS Name of Station in Lat. Long. : Hayford Fe ec Niners 1908 | 1910 | 1908 | 1910 1/Between Honolulu and San cm cm em em Francisco, at sea -_-.___- 5100 |28° 10’ N|146° 35’ W|—0-001 —0-010) + 0.003) —0-006 2\Tonga Plateau, at sea-__---- 2700 |28 20 S\178 27 W)+ 215) + -264)+ -207/+ -256 3/Tonga Plateau, at sea______ 2700 27 15 S177 40 W/+ -135)+ +161)+ -124/+ +150 4\Tonga Deep, at sea ------_- 6500 |22 07 S174 13 W/— -271)— -273)— -181/— -183 5/Tonga Deep, at sea -. ___- 8500 17 09 S171 42 W\— -248/— -245/— -162)— -159 6|Near Hawaiian Islands, atsea) 4000 |22 50 N\160 23 W\+ 034)+ -062)+ -023)+ -051 7|Near Oahu, at sea _ ___---- 1700 21 17 Njl58 17 W/+ -278)+ -304)+ -203)+ -234 Mean with regard to sign ___ | +0020) +.0-038) +.0:031) + 0-049 Mean without regard to sign 0-168; 0:188| 0:129) 07148 *Hayford, J. F. The Effect of Topography and Isostatic Compensation upon the Intensity of Gravity. Cf. Report of the Int. Geod. Association for 1909, published in 1910, pp. 365-389. L. A. Bauer—Gravity Determinations at Sea. 15 In the first place it is seen that Hecker’s mean Ag for the seven points here considered is larger for the 1910 figures than for the 1908 ones—whether the mean is taken with or without regard to sign. Next, the differences on Hayford are in every instance larger quantitatively for the 1910 figures than for the original ones of 1908 except for No. 5. Furthermore the difference, Hecker-Hayford for station No. 2, viz., +0°207 for 1908 and +-256 for 1910, is greater than any residual thus far shown upon Hayford’s computed g’s. For 56 pendulum stations in the United States Hayford’s computed values differed from the observed ones, on the average, by less than 0:02, the maximum difference being 0°094, this occur- ring at Seattle, known to be locally disturbed. Here are the differences for some very disturbed pendulum stations : TasLeE IV.—Some VERY DistuRBED LAND STATIONS. Height Station above Latitude | Longitude! g,-g. sea level m | cm lslom@lmllhn = 22.0 a Seaesensogee 6 21°18’ N |157° 52’ W, +0:0838 Mauna Kea (voleano) -_-.---. 3981 19 49 N |155 29 W) + 184 Hachinohe (Japan)____---.--- 21 40 31 N |141 30 EH) + ‘111 St. Georges, Bermuda-------- 2 32 21 N | 64 40 W| + -019 Jamestown, St. Helena_---- -- 10 15 58 S| 5 44 W) + -059 Sorvaagen, Norway _____----- 19 67 54 N | 13 02 E) + 147 Kala-i-Chumb, Turkestan ---- 1345 Bem Ne 0m Gm Ep 052 Gornergrat, Switzerland _----- 3016 45 59 N| 7 46 EH + -050 St. Maurice, Switzerland ___-- 419 46 13 N! 7 00 E| + -004 It will be noted that only in the case of two very remark- able stations—the voleano Mauna Kea and Sorvaagen, Norway, Hayford’s computed g, differs from the observed g, by more than 0-11 and in both of these cases the differences are less than 0-2. But Hecker’s revised figures of 1910 give five out of seven residuals over 0-1 and two above 0°2. Whether Hay- ford’s method fails for such deep sea stations as here considered or whether we have thus afforded an indication of the absolute error of Hecker’s values, it is not for me to say. It is curious, however, that Hecker’s supposedly most correct values (those for 1910) accentuate the differences on Hayford. Other detailed examinations made have not revealed any superiority of the 1910 method of adjustment over the pre- vious one. The difficulty with some of the port observations, e.g., at San Francisco, was found to be chiefly due to énstru- mental changes (change in thermometer corrections). If the port observations are omitted, as Hecker desires, then the mean difference in Ay between his two computations without regard 16 LZ. A. Bauer—Gravity Determinations at Sea. to sign is 0:°022™. The individual differences occasionally amount to 015°". He finally s says: “All conclusions drawn in the previous publications remain unaltered.” These main conclusions are : “The acceleration of gravity over the oceans traversed is approximately normal and conforms with Helmert’s gravity formula of 1901. Pratt’s hypothesis of isostatic adjustment of the masses of the earth’s crust is thus, except for local anoma- lies, found to hold true generally. It can be regarded hence as proved that the lesser density of the water of the oceans is compensated for by the increased density of the masses below the ocean bottoms.” My contention is that this conclusion was already practically embodied in Hecker’s method of adjustment. The conclusion may be true, but it can not be considered as proved by his mode of attack. Since no attempt was made to test whether another formula for normal gravity might not still better con- form with the observations, ‘the statement at the close of the first sentence does not seem warranted. Observations on Hecker’s Ocean Gravity Work. 1. No wholly satisfactory measure of the absolute accuracy of the existing ocean gravity results can be secured by a mere perusal of the publications. If an independent examination is made and such checks applied as are possible, and when all sources of error are considered, it will not be surprising if it be found that many of the most recently published results are in error by an amount approximating to 01°, or about 1/10,000 part of g. In view of the pioneer nature of the work, it would have been desirable to have repeated observations, under dif- ferent conditions, over all regions previously traversed. 2. One of the chief sources of error is to be ascribed to in- constancy of the corrections of the boiling-point thermometers caused by their continued and protracted use; the error thus arising may at times transcend in importance all other ones, an error in the temperature of 0:01° C. corresponding to about 0°35 in g. Insuflicient attention was paid to purely instru- mental changes and corrections. Thus, for example, correc- tions for the boiling-point thermometers of the Atlantic Ocean work of 1901 were used practically unaltered throughout the subsequent cruises of 1904 and 1909—after having once been supplied by the Physikalische Reichsanstalt, the corrections were never again redetermined. No separate examination of the barometers by comparison with standard barometers appears ever to have been made. The belief that such purely instru- mental changes would be fully taken account of im the adjust- DOr val Bauer—Gravity Determinations at Sea. 17 ment is shown to be fallacious. A source of error also not considered is that due to possible imperfections of the vapor tension tables. 3. Insufticient evidence has been given to prove that, in the reduction of the observations, it is best to omit those made on board vessels at anchor. A method of adjustment which must assume practically what is to be proved, and which necessitates the rejection of data secured under supposedly the best conditions, weakening thereby the connecting link between the ocean results and the shore pendulum stations, can hardly be regarded as the best possible one. Instead some logical method of observation and of adjustment must be striven for, which will take advantage to the fullest possible extent of the shore and harbor results. 4, The problem of obtaining sufficiently reliable ocean grav- ity results still awaits solution. Method to be Tried on the “ Carnegie.” The method it is proposed to try on the “ Carnegie,” begin- ning, if possible, at Cape Town in about April of 1911, is practically the same as that employed in the magnetic work. At all ports visited there will be both shore and harbor observations, especially at those places where g has been observed with pendulums and where accordingly the anomaly Ag is known, thus permitting a logical determination of purely instrumental constants. Our provisional equation of condition for such stations will be of the followimg form, @ having the same significance as in equation (1) above : p— 9% —h + a(t-t,) + b(B-B,). (10) k=k,+ k’, = constant part (%,) of the relation between the zero otf the thermometer and the zero of the barometer plus the constant part k’, of the errors of the vapor tension tables. It is hoped also by zero point determinations of the thermom- eters and by comparisons of barometers with port stand- ards wherever there are such, to determine #, independently of &’, and thus gradually get some idea of the various errors. a (¢—t,) is to represent the change in instrumental constants with elapsed time from some mean epoch, ¢,; it may later be found necessary to introduce a quadratic term, a’ (t—2,)*, but it is believed that, with proper care of instruments and with sufficiently frequent zero determinations of the thermometers, this term may be avoided. b(L-—8,) is to take account of the variations not included in the time term, but dependent upon barometric height or upon Am. Jour. Sci.—Fourts Series, Vou. XX XI, No. 181.—January, 1911. 2 18 LZ. A. Bauer—Gravity Determinations at Sea. boiling point; we may possibly find that this term can be taken account of by the special observations for %, as mentioned above. Hecker’s term a = is to be eliminated partly by method of observation and partly by refinement of instrumental appliances. The three terms, bp +cr+ds of his equation (No. 5), supposed to represent the effects of the ship’s motions, we shall endeavor to make negligible as far as possible or reduce to one term, dp, partly by the manner and place of mounting and by construction of the barometers, and partly by the scheme of combination of the observations, so as to introduce varied conditions of motions of vessel. It is thus hoped to avoid any need of a laborious and time-consumizg adjustment of the ocean results, thereby enabling the observer to make as nearly a complete reduction of his observations aboard as may be possible, the determination of the effects from instrumental causes disclosed by the shore and harbor observations being left to the office computer. The various sources of instrumental error—thermometer and barometer—are at present being further examined. It is possible that the temperature of the boiling point will be deter- mined both with mercurial thermometers of special construe- tion and with electrical resistance thermometers. The chief difficulty now appears to be in the sufficient refinement of the barometric work. The hope is entertained, however, that the great importance of getting values of g within the accuracy demanded by geodosists—about 0:02 or 0:03°°—will lead some one to discover a method so superior as to eliminate the boiling point-barometer method altogether for ocean gravity work. R.S. Bassler—Deep Well at Wuverly, Ohio. 19 Art. Il.—The Stratigraphy of a Deep Well at Waverly, Ohio ;* by R. 8S. Bassiur. Some months ago, in the course of routine work at the National Museum, the writer had occasion to identify a num- ber of characteristic Eden fossils from a set of photographs sent for determination by Mr. Peru Hutt, of Waverly, Ohio. The occurrence of this fauna at Waverly, in a region of Missis- sipian strata more than 60 miles from the nearest outcrops of the Eden formation, led to a correspondence with Mr. Hutt, in which it was learned that the originals of the photographs had been obtained from a deep well drilled for oil at that place. Mr. Hutt had carefully saved enough samples from all of the material resulting from the boring to prepare two very detailed logs, which he was kind enough to forward for study. He is to be commended for his zeal in the matter, for, without his eare, the following determinations, which are believed to be of some interest, concerning the underground stratigraphy could not have been made with any degree of accuracy. The notes resulting from the study of the two series of sam- ples were discussed with Dr. E. O. Ulrich at the time, and then set aside for future reference. Later the subject was mentioned by Dr. Ulrich to Professor Schuchert, who, in turn, deemed the section of sufficient importance to request a short article upon it for this Journal. The well was drilled to a depth of 3,320 feet. The upper 1,100 feet were cased, so that the samples from this portion were little mixed and afforded an accurate idea of the various formations penetrated. The lower 2,220 feet, however, were left open, and the samples from this part required more careful study. Still, this latter portion was not difficult to decipher, since the predominating foreign material in the lowest samples was the blue limestone and shale of the Cincinnati group, which had fallen from above, and which, on account of litho- logic characters totally different from those of the white mag- nesian limestone and sandstone of the lower formations, could easily be eliminated. Instead of giving a detailed description of each of the many samples, the results of the study are arranged below in the form of a geologic section. Drilling commenced at a point 100 feet below the top of the sandstone quarries of the town, and the first 35 feet of the well passed through the lower por- tion of this sandstone. Then in descending order came the black Ohio shale, the limestones and sandstones of Devonian and Silurian ages, a good representation of the various Cincin- * Published by permission of the Secretary of the Smithsonian Institution. 20 R.S. Bassler— Deep Well at Waverly, Ohio. ‘natian formations, a fair thickness of Trenton, Lowville, and Stones River, typical Saint Peter sandstone, and, finally, about 300 feet of rocks assigned to the Canadian. The various thick- nesses given must be considered as only approximate, mainly because they were calculated from two distinct logs. For some reason the samples had been arranged in two sets, one measuring from the top to a depth of 2,020 feet, and the other from the bottom to a height of 2.200 feet. The two overlapping por- tions were correlated with little difficulty, because this part of the section was the most fossiliferous. The base of the well is of particular interest and will be discussed later. Geologic Section at Waverly, Ohio. Thickness in feet. Depth. Mississippian: (b) Fine grained, drab ‘‘ Waverly ” sand- stone exposed in hills of town above mouthviok well: p:2 44; ae te as ee same OO) Similar standstone forming lower part of Waverly, series yess pease ee 35 0- 35 (a) Bituminous, fissile, black Ohio shale-. 450 35— 485 Devonian and Silurian: Mainly white, fine-grained sandstone with traces of white limestone. This material is so ground up by the drill that the limestone which it may have contained in some quantity has been mainly pulverized and washed away. The sandy material is evidently mostly from the Obio Silurian formations. At the base of this portion are the red and brown calcareous sandstones of Clinton ager? 227 22a ae eee eres 415 485— 900 Cincinnatian: (c) Blue shale with a few fragments of blue limestone. Fossils scarce, small portions of only Dalmanella jugosa being seen, but the strata are evidently of Richmond and Maysville age, with probably the Upper Eden shales rep- ; ReseNbe eee. oe oe 1065 900-1965 (b) Blue shales containing rather numer- ous Middle Eden fossils. ‘The species identified are: Rafinesquina alternata (Eden variety), Plectambonites seri- ceus, Dalmanella multisecta, Trematis millepunctata, Pholidops cincinnati- ensis, Callopora sigillarioides, Clima- cograptus typicalis, Byssonychia vera, Protowarthia cancellatu, Ceratopsis R.S. Bassler—Deep Well at Waverly, Ohio. 21 Thickness in feet. Depth. chaumbersi, Bythocypris cylindrica, Trinucleus concentricus, Calymene cal- licephala, Proetus? spurlocki, and Nereidavus varians. From this point to the bottom of the well, blue shale fragments holding this fauna were en- countered, but, eliminating them, the remaining formations were, for the main part, clearly represented in the SACOLOS arse ban Sear = ye ee 55 1965-2020 (a) Unfossiliferous blue and greenish shale associated with the blue shale holding the overlying Middle Eden fauna. This portion probably represents the Lower Eden and Utica divisions... -- 80 2020-2100 Mohawkian: Trenton formation. Blue clay and shale, with a few frag- ments of blue limestone. Zygospira recurvirostris, Trinucleus concentricus, and a species each of Khinidictya and Callopora, known elsewhere from the Lower Trenton, were noted. At the base of this formation a small amount of glauconitic grains were present in the*sanmples ey wae keen heh oe 125 2100-2225 Lowville and Stones River formations. Each of these formations is probably represented, but their lithology is so similar that no distinction could be made in the samples, which consisted mainly of white, clayey, and dove un- fossiliferous limestone with blue argil- laceous limestone at the bottom __-.- 600 2225-2825 St. Peter sandstone. White, saccharoidal sandstone ---- -- 175 2825-3000 Canadian. This portion naturally contained the greatest mixture of materials, but after excluding all the rock formations of the overlying beds, a few fragments of white dolomitic limestone remained. These are quite similar to the Cana- dian rocks of the Appalachians, and for that reason and the absence of chert, which is more characteristic of the Ozarkian, as well as the stratigraphic position, the correlation was made as above. .At the very base of the well a few small fragments of an igneous rock were detectedinn - 98222 2225... 320 3000-3320 92 Rk. 8. Bassler—Deep Well at Waverly, Ohio. This section presents no new facts regarding the rocks younger than the Trenton, for between Waverly and Cincin- nati, about 80 miles west, the same strata have been studied along numerous surface outcrops. The earlier Mohawkian formations are not exposed until central Kentucky, over 100 miles distant, is reached, while the Saint Peter sandstone and Canadian limestone are not known at all by surface outcrops in the Ohio valley. The section of strata penetrated by a deep well at Oxford, Ohio, is of interest in this connection. A detailed description of the log of this well was given by Joseph F. James in vol- ume X of the Journal of the Cincinnati Society of Natural History, but for present purposes only the general section determined by him is of interest. Arranged in the same form as the one given aboye, this section, with the formations as identified by James, but with the correlations of the present day inserted in brackets by the present writer, is as follows : Geologic Section, Deep Well at Oxford, Ohio. Thickness in feet. Cincinnati group: Blue limestone and shale [Richmond and Maysville]-- 360 Blue shale |[Maysvallevand ident] S25 ee = oe ae oer 380 Dark limestone! | @remt om) = eS cae eon seen ae Trenton group: White limestone with magnesia [Lowville and Stones River | 2 oes eee e)e ep ere Ce ae ee BO os Calciferous sandrock: White, arenaceous limestone [Saint Peter] ._--.------- 40 Unfortunately this well did not go deep enough to show the strata underlying the Saint Peter sandstone, nor did certain deep wells bored at Cincinnati pass beyond this formation. These Cincinnati wells showed the same stratigraphy and essen- tially the same thickness as in the Oxford well, so that the latter can be taken as typical for the region of. the Cincinnati axis. Comparing the Oxford and Waverly sections, the follow- ing conclusions may be drawn: (1) From observations on both sides of the Cincinnati axis, the Maysville and Richmond divisions of the Cincinnatian do not vary enough in thickness to suggest marked decrease of deposition across the apex of the axis. The Utica is seldom more than a few feet thick at Cincinnati. In northern Ohio it has become greatly thickened, as shown in the gas wells; it has likewise attained a considerable thickness in the Appala- chians. The increased thickness of the Cincinnatian as a whole a R. 8. Bassler—Deep Well at Waverly, Ohio. 23 in the Waverly well is thus probably due to the presence of greater deposits of Utica shale. (2) The same eastward increase in thickness may be stated for the Trenton rocks with less doubt. At Cincinnati the lower 50 feet of the Trenton are exposed with the thin Utica shale resting upon its eroded surface. Proceeding southeast along the Ohio River, this thickness increases to over 100 feet, in a distance of 30 miles, by the addition of higher beds of the formation. The occurrence of 125 feet of Trenton strata at Waverly, 80 miles east, is therefore in line with the idea that the Trenton and the Utica are alike in having a minimum thickness along the Cincinnati axis. These same facts, among others, have convinced several of the students of Cincinnati geology that this axis did not pass along a northeast-southwest line 25 or 30 miles east of Cincinnati, as commonly believed, but close to the city itself. Allowing for a certain amount of error in determination, the Stones River—Lowville sequence is practically the same in cach section. At any rate, both the Stones River and Low- ville are among the most widespread Ordovician formations, extending from Oanada to Alabama, and from New York to the central Mississippi Valley. Both the Oxford and Waverly wells are interesting, therefore, in indicating the presence of both formations in the northern part of the Ohio Valley, where they have no surface outcrops. The presence of such a typical fauna of Middle Eden species, a hundred or more miles from the shores of the sea of the time, is evidence for the shallowness of the early Paleozoic continen- tal seas. Deep wells elsewhere have furnished abundant proof of this same fact, and the one at Waverly simply furnished an additional well-established example. This Eden fauna is well known in New York, in the Cincinnati uplift,and in the Appa- lachians, and not being pelagic, it could not have had such a eeeereipe had deep seas intervened between these several shore ines. The occurrence of glauconitic material in the samples from the base of the Trenton is likewise noteworthy in indicating the unconformity between this formation and the underlying Lowville strata. Detailed studies of the early Paleozoic rocks have shown glauconite to be a common ingredient of the basal sediments of several overlapping formations. Perhaps the most interesting fact brought out by this well is the presence of a few fragments of igneous rock at its very bottom. The importance of this occurrence was suggested at once by Doctor Ulrich, for the area about Waverly is on the northward extension of the uplift which he has named the Car- ter axis. The igneous nature of these fragments was verified 24 RR. S. Bassler—Deep Well at Waverly, Ohio. by Dr. George P. Merrill, who determined them as peridotites which had become altered into serpentine. That the presence of this igneous rock is to be considered as indicating that the well passed through the base of the Paleozoic cannot be posi- tively determined from the facts at hand, as the material may possibly have been derived as a bowlder from above. However the facts so far as known are highly significant, and it may be tentatively suggested that the Canadian rocks rest upon pre- Cambrian. Whether this area was a part of an axis of uplift, such as the Carter axis, or was included in a broad southern extension of the Laurentian shield during Cambrian and Ozark- ian time, cannot be decided with the present evidence. U.S. National Museum, Washington, D. C. eX, ee ee eee ee ee Foote and Bradley—Solid Solution in Minerals. 25 Arr. IL.—On Solid Solution in Minerals with Special Reference to Nephelite; by H. W. Foorm and W. M. BRADLEY. Ir is a fact well known to mineralogists that there are certain minerals to which no satisfactory chemical formule can be assigned which agree with the results of analysis. The reason for this in many eases, particularly where the mineral is rare and little investigated, is probably that the material is impure, containing included foreign matter, or else the analysis is incorrect. There appear to be cases, however, where the material has been so carefully selected that foreign matter could not be present except in traces, and where analyses have been made with the greatest care and still the formula cannot be definitely assigned. A case of this kind is that of the mineral nephelite, to which the formule NaAISiO, and Na,A1,Si,O,, besides others more complicated have been given. An examination of several good analyses of this mineral will show that the analytical data do not support any one formula, but that there are considerable variations from it which are greater than can be accounted for by the ordinary errors of analysis. In general the composition of a mineral as obtained in analysis varies from the composition of the ideal pure com- pound for two reasons, aside from errors of analysis. Either there is (a) isomorphous replacement of one element or radical by another, or (>) there are mechanical impurities present. Where there is merely isomorphous replacement, the formula of the pure compound can be derived from the analysis by the ordinary methods of caleulation, which need not be considered here. The presence of mechanical impurities can usually be determined by other means, for instance, by the use of heavy solutions or by microscopic examination. We wish to call attention to another influence which must probably be taken into account in cases like that of nephelite. It appears to us necessary to assume that in certain cases a substance on crystal- lyzing forms a solid homogeneous solution with foreign matter which cannot be assumed to be isomorphous with any constit- uent, and which is not to be regarded as a mechanical mixture. It can be compared to the solution of salt in water, in which the salt takes on the appearance and form of the water without taking any part in the formula of the water. A case of this kind in minerals would not be a mechanical: admixture of the foreign substance, comparable to the suspension of a solid in water, but would form a homogeneous mass with the rest of 26 Foote and Bradley—Solid Solution in Minerals. the mineral comparable to the salt solution. If such an impurity were present in appreciable amount, it is obvious that the formula of the pure compound could not be caleulated correctly from the analysis. This type of solid solution must be clearly distinguished from isomorphous replacement, which is also commonly considered as solid solution. In the latter case, the formula of the compound can be derived directly from the analysis, as previously mentioned. Before considering the application of these statements to nephelite, we wish to mention a simple case of solid solution which is known in artificial crystals. It has been shown by Roozeboom* that when ammonium chloride crystallizes from a solution containing ferric chloride, the crystals deposited are colored and may contain as much as seven per cent of ferric chloride. Here there can be no question of isomorphous replacement, and on the other hand the ferric chloride is not mechanically enclosed by the ammonium chloride. The latter point is proved partly by the fact that the crystals appear pertectly homogeneous, and it is proved much more definitely by the fact that the solubility of such erystals varies with their composition. If a mechanical mixture were present, the solu- bility would not vary with the composition of the mixed crystals, but there would be a definite solubility at a given tempera- ture independent of the composition. The colored crystals are to be regarded as one homogeneous phase in which the ferric chloride is held in solid solution by the ammonium chloride. Similar occurrences have been noted in artificial minerals with a good deal of probability. Day and Shepherdt have observed an artificial calcium metasilicate crystallizing with tridymite which differs slightly in optical properties from the pure silicate. The variation appears to be due to the presence of silica taken up in solid solution by the metasilicate. The same metasilicate is also capable apparently of absorbing a considerable amount of the orthosilicate and still appear homogeneous. Again, Shepherd and Rankin{ have shown that artificial corundum may take up a limited amount of sillimanite (or silica) in solid solution and also a small quantity of calcium oxide. We believe such cases also exist in certain minerals such as nephelite. Several years ago, the late Prof. S. L. Penfield suggested to one of us (Bradley) that the reason for the variation in the composition of nephelite might be due to the presence of mechanical impurities and that if material of undoubted purity * Zeitschr. f. phys. Chem., x, 145, 1892. + This Journal (4), xxii, 265, 1906. {This Journal (4), xxviii, 293, 1909. Foote and Bradley—Solid Solution in Minerals. 27 could be obtained so far as mechanical admixture was con- cerned an analysis would show the correct formula of the mineral. A sample of nephelite from Eikaholmen, Norway, was chosen for analysis and freed from other minerals by use of acetylene tetrabromide. The sample used in analysis floated when the specific gravity of the liquid was 2°638 and sank when it was lowered to 2°632, so that variation in the density of the mineral was not more than -006. The resulting nephel- ite contained a minute amount of albite which was insoluble * in hydrochloric acid, but the quantity was so small thatit could be neglected. The material obtained was, we believe, as pure as it is possible to obtain nephelite by mechanical means, since observations under the microscope showed the sample to be of excellent quality and practically homogeneous. Two complete analyses and two other partial ones were made on this material with the greatest care (by Bradley). Only brief mention seems necessary of the methods employed im the chemical analysis. Silica was determined in the usual way, after dissolving the mineral in hydrochloric acid and by testing its purity traces of alumina were recovered. Alumina was precipitated as hydroxide and this was dissolved, repre- cipitated and weighed in the usual manner. The small per- centage of iron was determined volumetrically with potassium permanganate. A Smith’s fusion was made for the alkalies. The results in detail with the ratios obtained are given below. Taste I, Analyses of Nephelite (Bradley). Nephelite from Hikaholmen, Norway. perc 2 3 4 Average Ratio SiO, 44:59 44:31 44:37 44°59 44-46 -736 = 2:93 BOR asso yn on 02 es ola Wari t 185 Wie 824 anes ier O: 96 “96 ‘96 sons 96 :006 ay KEOe (562) 5:62 . 155% 15:59. 5-61. -060 BIG) Sy NO SiG Onn 1631 Gia W606, 16-325 263 tae” H,O emt cae ap asa cae 101:43 100-60 100-29 100:84 The above analyses were not published at the time they were made, as the formula derived from them was complex, and the results could not be regarded as establishing the formula. * Taken from anal. I. 28 Foote and Bradley—Solid Solution in Minerals. The composition of nephelite was further investigated the following year by Morozewicz,* who also gives an excellent review of the literature on the subject. The author gives analyses of six different nephelites which were apparently made with the greatest care on carefully purified material. By his method of analysis, he was able to free his material from even a trace of albite. The results and the ratios derived are given below. Taste II. Analyses of Nephelite (Morozewicz). i II Tit Nephelite (Elezolite) from Mariupol. Nephelite (Elolite) from Mariupol. Porphyritic Crystals. Coarse and granular. Ratio Ratio SiO, occas oes RSTO Mere Sem 43-46 TO. 61. ane 10 { 22 Oa oe 07 f Ae EAR O ae oes 33°12 ‘ AON eet ee 32°82 ; Re es bas) (200 Maney a ors} 100 CAO ye ieeee 0°49 CaQ a2 ee 0°31 EO yee 5°69 0799) 1) AS O Pee ee 5°55 0°99 NaI O's eee 15°91 Nia: Oe see 16°12 EE OS 0°74 AU Ress Meare 0°89 100°18 99:97 IV ; Vv Nephelite (Eleolite) Mariupol. Nephelite (Elzeolite) from Miask. Reddish Crystals. Ratio Ratio SiOmes ee 43°55 SlOve sg. eee 42°71 : 9) sap . PHO, sone st 0 t ar OP ab 0-04 } gue INCOM eat 32°96 Poa Ni OhGuu at a: 33°83 He Oe 0°66 t 100 ss tel) hy. Mena G A Bee CaO Sere ee 0°25 } CaOiee ser 0°32 KP Ope oi 6°09 100 TE OL se 5°86 1:00 Manan bee 16-00 J NaiOne ns 16-46 YO ee ee ae 0°33 EO Peeires 0°18 MgO Be ae trace Impurities -. 0°06 99°86 99°86 * Bull. Acad. Sciences Cracovie, 958, 1907. Foote and Bradley—Solid Solution in Mineratls. 29 VI VII Nephelite from Vesuvius, Nephelite from Vesuvius. Different specimen from VI, Ratio Ratio Ste aes 49°53 SiOn so) ae 4334 Ona eae 0-01 ; Serle TON - Neen at aie ALO Cee ae 33:92 AO yee 33°75 Pome We ple? pots ray. 1200 CaQ pas Sr. 1b9'7) CaQ ie tees 2°20 | is pe 0:07 | MeOus. 5. 0:24 | 9 5 iFe(O ue ela! eps @enn lc ik Omen cl. Aevinig 08 Na,O meee Sate 15°12 | INEEOR See: 15°66 J EI Oye eepre ses 0°13 HORS ee 30 0528 Impurities... 0°24 100711 100'26 We consider the seven analyses given above to be the best which have been made on nephelite. A considerable number of other analyses have been made, however, and we give below a summary of the ratios obtained from the analyses given in Dana’s Mineralogy, page 425. The numbers are the same as in the Mineralogy. Tasxe III. Ratios obtained from Analyses of Nephelite given in Dana’s Mineralogy. SiO, Al,O; etc. Na,O etc. No. 1. OM 1:00 1:00 4 Oe 9°95 (45 “99 OF BOUT o6 1:00 4, 2-29 ss *95 5. 2°20 sf “91 6. 2°24 a 1°04 7. 2°18 ‘6 1°02 8. 2°24 ce 101 9, 2°31 ‘s 97 10. 2°60 “ 1°16 11. 2°24. << 1°05 UR, 2°06 oY °94. 13. 9°14 6G *93 14, 2°29 < “97 15, 2°19 Se “98 The summary of the ratios obtained in the seven analyses first given is as follows: 30 Foote and Bradley—Solid Solution in Minerals. Taste IV. Summary of Ratios from Analyses by Bradley and Morozewicz. No. SiO, Al.O; ete. Na.O ete. It 2°93 1:00 0:98 TT: Zroili ef 0°99 1606 2°21 ee 0°99 Ve 2°21 fs 1:00 ais Pa as 1:00 VI. 2-11 cs 1:02 VIL. 2°15 re 1:03 - In this table the ratio of Na,O: Al,O, is as nearly 1:1 as could be desired. There can be no question that soda and alumina are present in this proportion. The ratio for silica varies from 2°11 to 2°23, and this variation is greater than can be accounted for either froin errors of analysis, or from the presence of impurities. For imstance, analysis No. I contains more than two per cent excess of silica if the ratios were to be the same as in No. VI. There is no case known, we believe, where silica can be considered as replacing isomorphously either alumina or soda, and if it did in this case, the ratio between these two would not be simple. The same general conclusion as regards composition may be drawn from the ratios derived from older analyses given in Table III, though many of the analyses are probably not as good as the more recent ones. Morozewicz* has shown that the nephelites may be con- sidered as consisting of two series of compounds, a normal series and a basic one. The normal series should be repre- sented by the formula K,Na,Al,4.Si,43Oin410, in Which n=8, 9, 10, and 11, and the basic series by the formula K,Na,,Al,,O,,. By this series of variable formule, the variation in composition can be expressed. This method of representing the com- position is open to the serious objection that a chemical com- pound, so far as we know, does not vary in type. Isomorphous replacement, for instance, varies the composition, but the type of compound remains the same. If nephelite be considered a solid solution, the case becomes very different. A solution may be defined as a homogeneous mixture of substances which cannot be separated by mechani- cal means and whose composition varies continuously within certain limits. This definition distinguishes a solution from a suspension on the one hand and from a chemical compound on the other. It characterizes a solution of a salt in water, and a solid solution of ferric chloride in ammonium chloride and we * Loc. cit. —— Foote and Bradley—Solid Solution in Minerals. 31 can see no reason why nephelite should not be treated in the same class. This method of considering the composition of nephelite has the advantage of being much more simple than using a series of complicated formule, and it appears to us to agree with the facts. It need hardly be said that a chemical formula could be assigned to any solution but a different one would have to be used for each change in concentration of the solution, just as Moroscewiez uses a different formula for each nephelite. From what has been said, we think it fair to consider that nephelite as it occurs in nature is not a pure compound but a solid solution analogous to the solid solution of ferric chloride in ammonium chloride. It then becomes of interest to con- sider the probable formula of the pure compound which forms the basis of nephelite. This appears to be the orthosilicate NaAIlSiO,. This formula is supported in two ways: (1) Nephe- lite has the same crystalline form as eucryptite LiA1ISiO, and kaliophilite K AISiO, which are in the same group, making it very probable that the type of formula is the same in all three eases. (2) Artificial nephelites have been prepared by Doel- ter* which have the same general characteristics as natural nephelite and vary in composition from the formula NaAISiO, to compounds containing potash and an excess of silica corre- sponding to the mineral. Perhaps the point should be emphasized that nothing what- ever is known about the actual condition of the dissolved silica, whether it is present as dissolved albite or silica or leucite or in any other form, just as very little is known about the condition of dissolved substances in liquids as to whether they are combined with the solvent. It is certain, however, that the dissolved silica does not have the properties of either ordinary quartz or albite, since it is soluble in hydrochloric acid. In the same way, the properties of a dissolved salt are entirely different from the properties of the solid. The excess of silica which can be taken up by nephelite to form a saturated solution can apparently be determined from the data given by Morozewicz and ourselves. Where albite is found intimately mixed with nephelite it is evident that the nephelite must be saturated with silica and the excess of the latter has formed albite. In this case, therefore, the nephelite should have a constant ratio of silica to alumina, and these nephelites should contain the maximum amount of silica that ean be taken up. The influence of temperature in determining the composition of the saturated solution can apparently be neglected. In our * Zeitschr, f. Kryst., ix, 321, 1884. 32 Foote and Bradley—Solid Solution in Minerals. own specimen, albite was associated with the nephelite, and Morozewicz states that albite was present in the specimens con- taining the nephelites of analyses II and III and microcline- microperthite, which would have a similar effect, in analysis IV. The ratio for silica in these four cases is 2°23, 2°21, 2°21 and 2°21, which is as nearly constant as could be desired. In analysis V, where the ratio for silica is only 2°12, the mineral is stated to be exceptionally pure, with biotite crystals on the outside. In VI or VII, where the ratios are 2°11 and 2-15, sanidine was present which might have the effect of albite, tending to raise the ratio to the saturation point, but in just these two cases (from Vesuvius) the nephelite appears to be a later growth on the sanidine and not intimately mixed with it. In these cases, then, where albite or its equivalent was not formed with nephelite, the ratio of silica to alumina shows that the nephelite has not taken up the maximum amount of silica. The most basic rock containing nephelite with which we are acquainted is an iolite described by Hackman.* This rock contains essentially pyroxene and nephelite with smaller amounts of titanite, apatite and ivaarite. There is no albite, quartz or feldspar present. The nephelite in this rock had the following composition and ratios: Ratio si0, BOO 2 ps wee ee 43°98 O13 Al,O, a AY Aa 34°93 1°00 CaO pea laa ties ee 0.36 INaiOR: Sacre ee 16 mf 0°94 K,O Eres Das eae Sh Meta 3°83 99°86 Here, again, the silica is below what we may call the “saturation ratio” of 2°21. It would be of considerable interest if nephelites could be found which closely approximated the formula NaAISiO,,. From what has been said above, such an occurrence could only be expected where crystallization had taken place from a magma so deficient in silica that albite did not form. In conclusion, the authors consider that the arguments advanced in the present article may be applicable to other minerals. Work has already been begun on the mineral pyrrhotite with the hope that similar deductions may be applied to this mineral. Chemical and Mineralogical Laboratories of the Sheffield Scientific School of Yale University. New Haven, Conn., October, 1910. * Bull. de la Commis. Geol. de Finlande, 1900, p. 9. Watson and Powell— Age of Virginia Piedmont Slates. 33 Arr. [V.—Fossil Evidence of the Age of the Virginia Piedmont Slates; by Tuomas L. Warson and 8. L. Pow tu. CoNTENTS: Introduction. Virginia Piedmont Province. Slate areas of the crystalline region. Quantico slate belt. Fossils. Arvonia slate belt. Introduction. Recent detailed field study of the slate areas in the crystal- line (Piedmont) region of Virginia by the State Geological Survey has resulted in much important information bearing on the lithologice characters, structural and age relations of the rocks, and on the sulphide ore-bodies (veins) associated with the slates of the northeastern belt. Of especial interest are: (1) discovery of fossils in the easternmost one of the slate areas ; (2) recognition of voleano-sedimentary beds intimately associ- ated with the slates in several of the areas; and (3) evidence of - the age relations of a part at least of the sulphide veins in the northeastern portion of the crystalline region, which hitherto have been assumed to be pre-Cambrian. The present paper treats only of the discovery of fossils in the Quantico slate belt, with a brief statement of its strati- graphic position, and of that of the other slate belts in the Vir- ginia crystalline region. Discussion of the age relations of the sulphide veins and of the volcano-sedimentary beds associated with the slates will be treated in another paper, now in pre- paration. Virginia Piedmont Province. The Virginia Piedmont province (crystalline area) lies be- tween the Coastal Plain and the Appalachian Mountains. It extends from the Blue Ridge eastward to the western margin of the Coastal Plain, and it widens southward (map, fig. 1). Its width increases from 40 miles in the northern portion along the Potomac River to nearly 175 miles along the Virginia— Carolina boundary. The rocks of this region are the oldest in the state, and, excepting the areas of Triassic rocks, they are all erystalline. They comprise both igneous and sedimentary masses, in many places so altered from metamorphism, chiefly pressure and recrystallization, that their original character is indistinguishable. The region is made up of a complex of schists, gneisses, and granites, with which are associated some slates, quartzites and Am. JOUR. Sct.—FourtH SERIES, VOL, XX XI, No. 181.—January, 1911. >) Aa ee “a S ~ aS = Sn ae aoa a Se STS “ol -= S y i eN fyatnoa” oss 5 iG oe i S er, ae S | & \ r=
S
~
I's
V,
Age of
Cc SS
| ajeos azewixosddy
SS
aS ‘ “ (S09 puoypag pue yssayWy)-41aq UspmoUs
> aN INP VSS : (09 ajewaqyy) “3184 3uoWs| NVINEWWS
aN ‘ ; p . A
QR BIpUENA TVG 7 Neue Lode, f (sop SERED) pue Jainbney) -}aq UopUaIe\\
nN é (seg e1uerjAsq}0ds
= f Z pue “paojyers “wWeIj|!AA e2Ul4d) HEGoruenh B | i. oquo
Ss : /. ; (sop euueAn|4 pue Wweysulyong) “}ieq eluoniy
~ QN3931
>
>
18 -118°52
The values of 27, remembering that a centimeter scale was
used, are again surprisingly good. The shift is computed by
the above equation. It may be eliminated in the mean of the
two methods. The lens Z’ may be more easily and firmly
fixed than Z.
7. Collimator Method.—The objection to the above single-
lens methods is the fact that the whole spectrum is not in
sharp focus at once. Their advantage is the simplicity of the
means employed. If a lens at LZ’ and at Z are used together,
the former as a collimator (achromatic) and with a focal dis-
tanee of about 50°, and the latter (focal distance to be large,
say 150°") as the objective of a telescope, all the above diffi-
culties disappear and the magnification may be made even
excessively large. The whole spectrum is brilliantly in focus
at once and the corrections for the shift of lines due to the
plates of the grating vanish. Both methods for stationary and
rotating gratings give identical results. The adjustments are
easy and certain, for with sunlight (or lamplight in the dark)
the image of the slit may be reflected back from the plate of
the ovating on the plane of the slit itself, while at the same
time the transmitted image may be equally sharply adjusted
on the focal plane of the eye-piece. It is, therefore, merely
necessary to place the plane of spectra horizontal. Clearly a’
and @” are all infinite.
92 OC. Barus and M. Barus—Plane Grating Similar to
In this method the slide Sand D are clamped at the focal
distance apart, so that flame, ete., slit, collimator lens and grat-
ing move together. The grating may or may not be revoluble
with the lens Z on the axis a.
8. Data for the Collimator Method.—The following data
chosen at random may be discussed. The results were obtained
at different times and under different conditions. The grating
nominally contained about 15,050 lines per inch. The efticient
rod length ab was R=169'4™. Hence if 1/C=15,050~x
3937 X 338°8, the wave-length A = C-2x.
Grating Lines Qa! 2a cs
Stationary es eee DD. 118°30 118'19
Rotate eso .. -eae D, 118-08 118719
Stationary) suse e ese D, 118:27 118716
Rotate eles ae D 118-05 118°16
Rowland’s value of D, is 58°92X10-°™; the mean of the
two values of 2x just stated will give 58° 8710-2, The dif-
ference may be due either to the assumed grating space, or to
the value of # inserted, neither of which were reliable abso-
lutely to much within 1 per cent.
Curious enough an apparent shift effect remains in the
values of 2x for stationary and rotating grating, as if the colli-
mation were imperfect. The reason for this is not clear,
though it must in any case be eliminated in the mean result.
Possibly the friction involved in the simultaneous motion of
three slides is not negligible and may leave the system under
slight strain equivalent to a small lateral shift of the slit.
9. Discussion.—The chief discrepancy is the difference of
values for 2v in the single lens system (for D,, 118-7 and
118'5°", respectively) as compared with a double lens system
(for D,, 118-2°") amounting to *2 to ‘4 per cent. For any
given method this difference is consistently maintained. It
does not, therefore, seem to be mere chance. The detailed
investigation, which must be omitted here,* made it clear that
the effect of focusing is without influence on the diffraction
angle and much within the limits of observation. It is, there-
fore, probable that the residual discrepancy in the three
methods is referable to a lateral motion of the slit itself due to
insufficient symmetry of the slides AA and BL in the above
adjustment. This agrees, moreover, with the residual shift
observed in the case of parallel rays in § 8.
10. Reflecting Grating—The adjustment of the plane grat-
ing if cut on specular metal is nearly identical to the above,
except that the collimator is fixed as a whole in front of the
grating, either to the slide carrying the standard of the grating,
B, or else quite in front of the cross slide AA, fig. 5 above,
* See Proc, Am. Phil. Soc., 1. ¢.
Rowland’s Method for the Concave Grating. nos
so as to give clearance for the to and fro motion of the rail, /2.
This admits of measurement of w on both sides of the slit, so
that 2v, the distance apart of the two symmetrical positions for
a given spectrum line, is again observed.
11. Rowland’s Concave Grating.—For the case of the con-
cave grating, the accurate adjustment for symmetrical meas-
urement on both sides of the slit is not feasible, because the
slit and eye-piece would have to pass through each other. It
is possible, however, to find conjugate foci at different distances »
from the grating in the normal position, which approximately
answer the purposes of measurement. Rowland’s equation
(cosz/p — 1/ &) cost + (cos 6/p’ — 1/p') cos 6 = 0
where p and p’ are the conjugate focal distances for angles of
incidence and deviation ¢ and @, may for 0 = 0 be written
1 lpm aligeecs
a CIO ~ Th CIs Say FI
where p, is the normal distance of the eyepiece, so that
1 1 2
If in figure 6, the slit S is put at p’ > & from the grating
G (normal position), the image is at Hat the end of p, from
G, where p, < H p. But this excess need not be so large as to inter-
fere with adequately sharp focusing.
The following table gives an example, in which the difference
of p, and p,’ in the normal position is even over 1 foot, an
excessive amount, as the distance necessary for clearance need
not be more than a few inches. The grating has 14436 lines
to the inch and a radius about R = 191.
TABLE II.
Conjugate foci of the concave grating. R=191°™, 14436 lines to inch,
5683 lines to em. D= ‘000,176.
po=166™,. p=198™, p—po=32™. 1/p.—1/R= 000788. 6=0, sin
i=A/D.
Fraunhofer
ae p Po cos t Diff. (p/cos i)? Lines a
em. em.
0° 166°0 166:0 0 27500 B 99° 59!
5 165°3 165°3 0) 27500 C 91° 54!
10 163°2 163°5 c=) 93} 27400 D 19° 34’
15 159°6 160°3 — "7 27300 EH 17° 26°
! 20 154°7 156°0 —1°3 97100 Ji 16° 02’
25 148°5 150°4 —1°9 26800 G 14° 10’
30 140:9 143'7 —2°8 26500
35 132°2 136°0 --3°8 26000
40 122°3 12771 —4'8 25500
94 CO. Barus and M. Barus—Plane Grating Similar to
The greater part of the visible spectrum is thus contained
between 7 = 15° and ¢ = 20°. It follows that the excess of
Po CoS 7 — p lies between 7 and 13"". Hence the eye-piece
may be placed at a mean position corresponding to 10™™" and
give very good definition of the whole spectrum without
refocusing, as I found by actual trial. Within 1™ the focus
is sharp enough for most practical purposes. If the distances
po and p,’ are selected so that eye-piece and slit just clear each
other the definition is quite sharp.
The diffraction equation is not modified and if 2a corre-
sponds to the positions + ¢ and — ¢ for the same spectrum line,
De (D/f) Phos
It is, therefore, not necessary to touch the eye-piece, and this
is contributory to accuracy.
Fic. 6.
If Rowland’s equation is differentiated relatively to p and p’
—dp = (—* / dp, , where the dp,’/p,’ factor is constant.
Po COS 7%
Hence — dp varies as (p/cos 2)’, given in the table. If further-
more a comparison is made between dp, and dp this equation
reduces to
a/dp,/dp = |(R—p,)(i—cos 7) |/F# cos z
which becomes unity either for 7=0 or for p, = (Rowland’s
case).
12. Summary.—By using two slides symmetrically normal
to each other and observing on both sides of the point of
—————
Rowlands Method for the Concave Grating. 95
interference, it is shown that many of the errors are elimi-
nated by the symmetrical adjustments in question. The slide
carrying the grating may be provided with a focusing lens in
front or again behind it, if the means are at hand for actuat-
ing the slit which is not shar ply in focus on the plane of the
eye-piece carried by a second slide throughout the spectrum at
a given time. It is thus best to use both lenses conjointly,
the latter as a collimator and the former as an objective of the
telescope in connection with the eye-piece. It is shown that a
centimeter scale parallel to the eye-piece slide with a vernier
reading to millimeters is sufficient to measure the wave lengths
of light to few Angstrom units, while the wave lengths are
throughout strictly proportional to the displacements along
the scale. The errorsof the three available methods and their
counterparts are discussed in detail. The method is applica-
ble both to the transparent and the reflecting grating.
It is furthermore shown that in case of Rowland’s concave
grating observation may be made symmetrically on both sides
of the slit, or for reasonable clearance of slit and eye-piece
passing across each other, although one conjugate focal dis-
tance is now not quite the projection of the other.
Brown University, Providence, R. I.
% HH. Z. Kip—Determination of the Hardness of Minerals.
Arr. XI.— Determination of the Hardness of Minerals, IT ;
by H. Z. Kier.
In the issue of this Journal for July, 1907, an article by the
writer on the subject of mineral hardness appeared, whose
threefold object was outlined as follows: 1. To invite general
acceptance of a single definition of hardness. 2. To establish
theoretically in conformity with the definition the best method
of investigation. 38. To put this method in practice by means
of suitable apparatus and adequate mathematical calculation.
Inasmuch as it is my present purpose to act as my own critic
as well as to publish the results obtained in carrying out the
investigations indicated above under 3, it will be found excuse-
able, perhaps, if I depart from the general practice of contribu-
tors to the extent of speaking in the first person instead of the
third.*
In regard to the formula for determining hardness, estab-
lished in my previous paper, H=~/a’+y’, I may say that no
mineralogist or physicist who has favored me with his opinion
has taken exception to this equation. Indeed so long as the
generally accepted definition of hardness prevails (resistance to
abrasion) this is, and ean be, the only adequate formula.
If in what follows I appear to view my own results with
some scepticism, I wish it to be understood that this is not the
result of a lack of faith in the method employed, but merely
an acknowledgment of the difficulty of dealing accurately
with molecular forces by mechanical means, such means, at
least, as I have had at my disposal.
The apparatus employed was described in its general prin-
ciples in my previous paper. As actually constructed it dif-
fered from the description given in two points only. —_—__.
Arr. XIX.—The Transmission of Light through Transparent
Inactive Crystal Plates, with Special Reference to Observa-
tions in Convergent Polarized Light; by Frep. EvcEnr
Wricu'.
Introduction.
Tue problem of the refraction and reflection of light on
inactive, transparent crystal plates has long attracted the atten-
tion of physicists and crystallographers, and has proved a
fruitful field of investigation from the standpoints both of
theory and of applied physical optics. The general problem
was first successfully attacked in 1835 by F. Neumann’ in Ger-
many and by J. MacCullagh’ in Ireland, Neumann using
strictly analytic methods; MacCullagh, on the other hand,
inclining rather to geometric methods and attaining thereby
greater simplicity in his treatment of the whole. Both Neu-
mann and MacOullagh showed keen mathematical insight and
judgment in overcoming the inherent difficulties of this prob-
lem; their work, moreover, was remarkably thorough and
comprehensive, and has served as the foundation on which all
subsequent investigations have been based. Their general
conclusions have remained intact and valid to the present day,
even though their methods of calculation have been superseded
by simpler and more effective methods and their fundamental
assumptions have been modified to some extent and expressed
in terms more nearly in accord with modern views on the
nature of light. ,
1 Theoretische Untersuchungen der Gesetze, nach welchen das Licht an
der Grenze zweier vollkommen durchsichtiger Medien reflektiert und gebro-
chen wird, Berliner Akad. Abh. 1835, Math. Abt. p. 1-160; also Poggen-
dorf’s Annalen. xlii, 1-37, 1837.
? Phil. Mag. (3), viii, 103, 18385; x, 42,1837; On the Laws of Crystalline
Reflexion and Refraction, Trans. Roy. Irish Acad. xviii, p. 31, 1887; Col-
lected Works, 1880.
Am. JouR. Sci.—FourtH SrrRizs, Vout. XX XI, No. 183.—Marcz, 1911.
12
158) FE. Wright—Transmission of Light through
Besides the papers by Neumann and MacOullagh, the most
important contributions to this subject have been made by D.
Brewster’ (1819), A. Seebeck’ (1831), A. Cauchy® (1836), C. G.
Stokes* (1852), J. Grailich® (1855), A. Cornu’ (1867), G. Kireh-
hoff’ (1876), H. A. Lorentz* (1877), F. Kohlrausch’ (1878), R.
T. Glazebrook” (1882), Th. Liebisch” (1885), J. Danker" (1885),
J. Conroy” (1886), C. Spurge™ (1886), J. Norrenberg”’ (1888),
Lord Rayleigh” (1888), P. Drude’ (1889), C. Pulfrich* (1890),
A. Potier’® (1891), W. Voigt” (1896), C. Viola” (1899), A. Ost-
hoff” (1905), P. Kaemmerer* (1905), F. Pockels™ (1906).
In all these investigations, interest has centered in the
reflected rather than in the refracted waves. The phenoniena,
however, resulting from the transmission of light through
crystal plates are of great importance in practical microscopic
diagnosis and merit detailed consideration, from the standpoint
both of general theory and of observation. The present inves-
tigation was undertaken primarily to determine the influence
1Phil, Trans., 1819, p. 145.
BS Pogg. Ann., xxi, 290, 1831; xxii, 126, 1831; xxxviii, 276, 1836; x1, 462,
1837.
3Compt. Rend., ii, 364, 1836.
4On the composition and resolution of streams of polarized light, etc.,
Cambridge Trans. ix, 399; Phil. Mag. (4), ii, 316, 1852.
®'Wien Sitzungsber. (II), xi, 817, 1853; xii, 280, 1854; xv, 311, 1855;
xix, 226, 1856; Denkschr. Math. Nat. K1 ix, 57, 1805; xi, 41, 1856; Pogg,
Ann. xcviii, 205, 1856.
® Recherches sur la reflexion cristalline. Thése fac. Science. Paris, 1867;
Ann, Chim. Phys. (4), xi, 1867.
1 Uber die reflexion u. Brechung des Lichtes an der Grenze krystalliner
Mittel., Abh. Berliner Akad., 1876.
8Uber die Theorie der Reflexion u. Refraction d. Lichtes, Schlémilch’s
Zeitschr. xxii, 1, 1877.
9Wied. Ann., iv, 1, 1878.
10On the Refraction of plane polarized Light at the Surface of a uniaxial
Crystal. Phil. Trans. clxxiii, 595, 1882.
1Uber Totalreflexion an doppeltbrechenden Krystalien. Neues Jahrb.
i, 245, 1885 ; ii, 47, 1886 ; Lehrb. d. Physik. Kryst., 1891.
12 Neues Jahrbuch, Beil. Bd. iv. 241, 1885.
13 Proc. Roy. Soc., xl, 173, 1886.
4 Proc. Roy. Soc., xli, 468, 1886; xlii, 242, 1887.
15 Uber Totalreflexion an doppeltbrechenden Krystallen. Wied. Ann., xxxiv,
843, 1888. :
16 Phil, Mag. (5), xxvi, 241, 1888.
“Wied. Ann., xxxvi, 532, 865, 1889; xxxviii, 265, 1889. Physik. d.
Aethers, 1894. Lehrbuch d. Optik (2d edition), 1906.
18 Das Totalreflectometer, 1890.
19 Sur la principe du Retour des rayons et de la Reflexion cristalline, Journ.
de Phys. (2), x, 349, 1891.
*0Compend. d. theoret. Phys. ii, 622, 1896.
1 Zeitschr. Kryst., xxxi, 40, 1899; xxxvi, 245, 1902.
22 Uber die Reflexion u. Brechung des Lichtes an Zwillingsebenen volkom-
men durchsichtiger inaktiver, einachsiger Krystalle. Neues Jahrb., Beil.
Bd. xx, 1, 1905.
23 Uber die Reflexion und Brechung des Lichtes an inactiver, durchsichti-
gen Krystallplatten, Erster Teil. Neues Jahrb., Beil. Bd. xx, 159, 1905.
24 Lehrbuch d. Kristalloptik, 1906.
Transparent Inactive Crystal Plates. 159
of certain factors which underlie the methods for the measure-
ment of the optic axial angles, especially the method of Pro-
fessor Becke’ and the writer’s modification*® of the same.°
These methods are based on the degree of curvature of the
dark hyperbolas or zero isogyres of the interference figure and
depend, therefore, on the polarization directions of waves
transmitted along ‘different paths. In microscopic work, the
influence of the boundary surfaces, not only of the crystal
plate, but also of the intervening glass plates, on these waves
enters the problem and tends to render it more complicated.
In the following pages the general mathematical treatment of
the problem of ‘ight transmission through transparent inactive
erystal plates is given in. Part 1 and ‘several important and
apparently new yelations are deduced which simplify the
presentation materially. In Part 2 results of calculation are
checked by series of observations with apparatus specially
designed for the purpose.
The results of the investigation show that the methods pro-
posed by Professor Becke and by the writer are approximate
methods only; both furnish results of about the same order of
accuracy, the one advantage of the writer’s method being that
of slightly greater simplicity. They show, furthermore, that
a theoretically correct method is not attainable because of
many factors, each of only slight intluence, which enter the
problem and complicate the relations seriously.
Part 1.’— Theoretical.
The Boundary Conditions.’
Light waves, in passing through a erystal plate, encounter
peculiar conditions, both on entering the plate and emerging
from it. At the limiting surfaces of the plate, the crystalline
material ends abruptly and the system of forces which result
from the erystal strueture are suddenly cut off from further
action. On emerging from the plate the light waves pass from
the influence of these forces to that of an entirely different
1 Tschermak’s Mitteil., xxiv, 35, 1905; xxviii, 290, 1909.
This Journal (4), xxiv, 332-338, 1907; Tschermak’s Mitteil., xxvii,
293, 1908.
*In the course of this investigation the writer has corresponded frequently
with Professor Becke and is indebted to him for several suggestions and for
his open consideration of the points in question.
“In the preparation of this section the following books and papers have
been consulted especially: Drude, Lehrbuch d. Optik; also Drude in Win-
kelmann’s Handbuch d. Physik; Liebisch, Lehrbuch d. Kristalloptik ;
Pockels’s Lehrbuch d. Kristalloptik ; and P. Kaemmerer, Uber die Reflexion
u. Brechung des Lichtes an inaktiver, durchsichtigen Kristallplatten, Neues
Jahrb., Beil. Bd. xx, 159, 1905.
5 The subject of boundary conditions is thoroughly treated by P. Drude in
Winkelmann’s Handbuch der Physik, vi, 1169, 1906; also in Drude’s Physik
d. Aethers, 511, 1894.
160 FL E. Wright—Transmission of Light through
system, but this passage from the one set of conditions to the
second, although very rapid, is a continuous process, since,
physically speaking, there are no discontinuities in nature. On
the one side of the surface the light waves are entirely within
the influence of the crystal forces; on the other, within that of
the second medium; at the boundary surface, the transition
from the one sphere of influence to the second is accomplished.
There the two sets of forces meet and the result is a continuous
passage of the one set to the second, so far as their influence
on external forces is concerned. Whatever theory or hypothe-
sis of light is adopted to explain the phenomena, this contin-
uity must be taken into account. In the electromagnetic
theory of light a “ boundary’ surface between two substances
of dielectric constants e, and e, must be considered an inhomo-
geneous surface in which the dielectric constant passes contin-
uously though very rapidly from the value e, to e, in the
direction of the normal to the surface.” The general equations
of the electromagnetic theory are valid even in this film:
4r , Ow NA _ ou Ow 47, Ow dou
Gn” Foy! Gee? oom be) del ice) a co
Gy * 10a. soy! 2 ee Ok ios ate ~ meno i umnro ne
In these equations of Maxwell, u, v, and w are the compo-
nents after the a’, y’, 2’ axes of the magnetic force (the 2’
axis being normal to the surface and the ~’ axis in the plane of
incidence); X, Y, Z the components of the electric force;
Jx's Jy Juy the components of the electric density in electro-
static units ; Ss, ., Sy, S,, the components of the magnetic current,
and ¢ a constant, expressing the ratio between the electrostatic
and electromagnetic units. The components of the electric
and magnetic currents, 7., Jy, J, and s,., sy, 8, are finite quanti-
ties. The right hand side of the equations with differential
quotients must therefore also be finite, even when the thickness
of the film approaches 0, and the components of the electric
and magnetic forces parallel with the boundary surface must
_ be continuous on passage through the boundary surface. This
condition is realized mathematically by stating that on either
side of an infinitely thin film the two forces are equal.
(@),. = @),6°(%), =(@), (C2 =o, 1), = eee)
These conditions are perfectly general and must always be
fulfilled at boundary surfaces.
'P. Drude in Winkelmann’s Handbuch der Physik, vi, 1169-1170, 1906.
Transparent Inactive Crystal Plates. 161
Boundary Conditions Applied to Transparent Inactive Crystal
Plates.
A erystal is distinguished electromagnetically from an iso-
tropic body by the variation of its specific inductive capacity
with the direction. If «€,, €,, «,, be the three principal dielec-
tric constants of a crystal and mw the magnetic permeability,
= |, as is practically the case in all known dielectrics, then the
general differential equations, referred to any codrdinate sys-
tem, for the electromagnetic field in a crystal, are:
Dea a0) es 20S
e en ot + €, ot ar 13 a) ay Bev
| Ox era ot) _ 9 Jw (4)
= —— Sih de = = _ —=
ec 1 ot ap or ot 4 €o3 Ot dz! Ox! Y]
Mv OX en Ov OZ Oo Ou
Cc («: at E50 ot + €,, =]
Ty Ghee Vo
Lau _9¥_ 9% 180 _ 9% 9X 1dw_ dX OY
aero cnon mon) O20. ue OF Oy’ 1 Oz!
In these equations, €),—=€xn (').
If the magnetic force be taken as light vector, the compo-
nents X, Y, Z, of the electric force can be eliminated from (4)
and (5) by differentiating equations (5) with respect to ¢:
Ohh 6 (ey 9 ear 1 . A ee 9 @);
Goin Oe NOt) MeOu Not) 6 Ot Onl ob) m2) \ an) 2
Idi 2 0 /oX do /dY (6)
e Ot a) cal ae
IX IY OZ
and substituting the values from equations (4) which
Ot? dt? dt
are linear functions of these quantities. If, for abbreviation, the
right hand side of the equations (4) be made equal respect-
: OX JY OZ :
ively to &, 7, & then Dt? on? oe Can be expressed as linear
functions of &, », €, thus:
‘A simple proof of this relation is given in Drude, Lehrbuch der Optik,
294, 1906.
1620 FL EB. Wright—Transmission of Light through
Oxia dl
on = Cc (4,,€+4,,9+4,,0)
Vesa
Ot = Cc (4,,€ + 49 + Aa6) (7)
Amel
Ot a Cc (45, + G9 +4,,)
in which the so-called polarization constants @,,...,a,,...,
@,,. + . 5 aresimple determinate functions of ¢,...,6,..
€,--., and ¢’ and for which the relations a, = dy, hold
true just as €,, == €,. These equations indicate that a function
of the second degree is possible whose partial differential
quotients with respect to & 7», ¢, are equal, respectively, to
aX oY 97
ot? dt? Ot”
2cG = 4,6 +4,,4' +4,,0 + 20,6 + 2a,,CE+2a,,€) = constant. (8)
From energy considerations it is evident that this equation (8)
must represent an ellipsoid; and if, in it, the constant be
2¢G=1, the equation is then that of a triaxial ellipsoid referred
to a coérdinate system of any position. This ellipsoid is the
“index ellipsoid” of MacCullagh, or “ellipsoid of elasticity ”
of Kirchhoff, or the “indicatrix”’ of Fletcher. The codrdi-
nate axes can be brought to coincide with the principal
ellipsoidal axes by use of the usual transformation equations :
This function is
ap + Bp", +p’, = 0.
2,2 22 2,2 ae
OP POG, Vegan =a
2,42 PLP) taza =:
OT OTS Ci 9 =e
2 r 2 a : 42 a
a le OOP +e 9,1; ap, Ws (9)
wT Dp, ar br, DP, 3 CT, Dp, = 4,,
WPT, + OG. + OPI, = %
in which 7, Py Doo Yrs Yoo Yon And 7,, 7,, 7,, ave the direction
cosines between the new coordinate axes #, y, 2, and the w’, v’, 2’
of the old system respectively. Referred to the principal
ellipsoidal axes equation (9) becomes a*&’+6'n’+c*O* = 1, in
which a, 6, c, are the principal light velocities of the erystal.
The symmetry axes of this index ellipsoid are the reciprocals
of a, 6, ¢, or directly the principal refractive indices of the
crystal. In geometric problems of reflection and refraction,
the index ellipsoid and the index surface derived from it are
specially useful.
Transparent Inactive Crystal Plates. 163
On substituting the values of Bae ae Ze of equation (7)
in (6) we obtain a system of partial differential equations :
ae = = (Qe Gant 2.56) — 5 (14,8 + 529 + Ua06)
oe 3s = (Gygé + Gag + 4.6) — S (4,,€+@,.9+4,,6) (10)
ce = iu (a,,€+4,.n+4,€) — ee (4,,E + U9 + 4,06)
which are free from the components of the electric force and
of the electric current. 5:
Equations (4) and (5) are of general validity and obtain
therefore, even at the boundary surface of a crystal plate." alt
is apparent from the last equation of (5) that, as (X),= (X),,
(Y),=(Y), at the boundary, (3 i) = in or (w),=(w), for
periodic vibrations. The boundary conditions for a crystal
plate may therefore be written :
(0, = Hy =v (= oe (FE) = (Ge),
(ar), (5),
of which only four are independent. The last equation of
the set may accordingly be discarded. The fourth equation
a) = (Fe) can be expanded by means of (7) and (4) and
becomes for the general case of two adjoining crystal plates :
Pee) io aa, (2 Se
tu 50) — 5p +4,,(55— 5a T ys aay) =
, fow — ov’ Bay (Oi an os fou why
a le a oa) + a aCe Ox! ) +a da a (12)
These boundary equations, together with equation (8), are
of general validity for transparent, inactive plates, and form
the basis on which all detailed work rests.
The partial differential equations (10) representing the move-
ment of the magnetic vector are satisfied by the components
u, v, w of the vibration of a plane polarized, advancing wave
of constant amplitude. This vibration is defined by the usual
equations of the general form :
164 FL EL Wright—Transmission of Light through
U / /
“= Al cos aC Siw)
T q
if / '
v = Am cos all (« = ee (13)
T q
t J /
w = An cos p(e—-S ts)
T q
in which A is the amplitude of the vibration or magnetic
force; 7, m, n, the direction cosines of the line of vibration 7,
which in this case is that of the magnetic light vector and also
the polarization direction; T, the period of vibration; A, #, v
the direction cosines of the normal N of the wave propagated
with the velocity g. To simplify these equations, let the
boundary surface of the plate be the a’, y’ plane, fig. 1; the
AE
plane of incidence, the «’ 2’ plane; the angle between the
normal of the advancing wave N, and the 2’ axis, 7, the positive
direction of z’ being on the crystal side of the boundary
surface; let also the polarization azimuth yw be the angle
between the plane of incidence (the «’z’ plane) and the plane
of polarization (the angle Kz, fig. 1) counting from the 2’ axis
in the direction of the +7’ axis and passing beyond this axis
if necessary. In this case,
= cos 7
|
oS
_
== sin i
t= —cosrcosy, m=siny, n= sin? cos y.
and the equations (13) reduce to
Transparent Inactive Crystal Plates. 165
a x’ sin 7 +2! cos }
u= — A cosy cosr cos — —-
i qY
, 2 a'sin 7 + 2’ cos7r
Qs A sin y cos a(t — (14)
i q
: Qn a’ sin r + 2’ cosr
2o= Acosysinr cos —(t —
T q
For 2’ = 0 it is evident from the boundary conditions,
(wv), =(w),, (v), = (v), of equations (11) and (14), that for all pos-
sible reflected or refracted waves at the limiting surface, T, the
period of vibration (color) remains constant (T, = T,); also
oF By BS = fs , which is the sine law of wave normals; while
# =O signifies that all wave normals lie in the plane of
incidence.
By means of equations (14), the general differential equations
(10) can be solved and the fundamental formulas obtained for
the refraction, reflection, and polarization of light waves in
erystals. Thus from equations (4) and (14)
ow ow
é Syme: sin yw cos 7
Ou Ow
ee acme ping. ha COSY
dv ou , :
= gi Dy! = K sin wy sin 7.
W herein
9 i D) i I SI “4 I a
eS es sin sp (¢— CaS eas o*)
T.g T qd
From these expressions, we find:
p ;
)
Oz! (2,, 5 a Ayo) a Aes é) =
| a cos 7 (—a@,, Sin ¥ Cos 7 —a,, cos y +4a,, sin y sin 7’)
)
Ox’ (a,,€ oF a, ate Ass é) =
Cae : ; A
ee sin 7 (— @,, sin y cos 7 — @,, Cos + Q,, Sin W sin 7)
}
Oz! (4, g — a). SUE a,, é) =
C ; : ;
ae cos r (— a@,, sin y cosr — @,, COS Y + @,, Sin y sin 7)
166 FF. EB. Wright—Transmission of Light through
4)
°
Ox" (4, 3 ai; 4 tr Ms é) ==
—; sin 7 (— @,, sin y cos 7 — a,, cos y + @,, sin y sin 7)
Wherein
Cay all ie Qa (+ a! sin 7 + 2’ cos 7
T de q
similarly from (14)
Ou
>A atari Cosh tan Ns 3
ov ‘ ;
oF = C sin y
ow é
cava ae C cos wy sin 7
Substituting the values from these last two sets of equations
in (10), we obtain the two equations
1 4 “ 4
—cos Ye Phe sin y cos 7—a@,, cos W+a,, Sin ysin”) and
; sin r 4 : F |
sin y= Fe (—a,, sin Y cos r—a,, cos Y+@,, Sin y sin 7) — |
cos 7 6 ;
(—a,, sin Wy cosr—a@,, cosy+a,, sin y sin 7)
2
which, on rearrangement, become
(a) cos y (¢’—a,,)=sin wp (a,, cos r—a,, sin 7) (15)
(0) cosy (a,, cos r—a,, sin 7) =
sin y (¢°—a,, sin’r7—a,, cos’r+ 2a,, sin 7 cos 7)
By division of 15 (a) by 15 (6) an expression results which is
free from y;
(7’—4a,,)(¢°—4,, cos’*”r—a,, sin’*r +2a,, sin r cos 7)= (16)
(@,, COS 7—a,, Sin 7)”
and which reduces to’
[4, 1 a 20,19 ui a (4s, —k'/ig’r | [Go ar (Go —k*)tg’r| — (16a)
; (@,,— A, .9 ry(1 +t9*r)
if & be substituted for the constant value = which, by reason
of the sine law of refraction, is equal, for all possible waves, to
es where g, is the velocity of light in the isotropic medium
enveloping the crystal and 7 the angle of incidence. By means
of this standard formula, which can be derived in different .
1G. Kirchhoff, Uber die Reflexion und Brechung an der’ Grenze Krist.
Medien, Berliner Akad. Abh., 1876.—Th. Liebisch, Neues Jahrbuch, II, 191,
1885.
Transparent Inactive Crystal Plates. 167
ways, the angle of refraction or reflection of any light waves
in the erystal can be calculated.
From 15 (a), the following equation is readily derived :
t/a
gw= q 22
@,, COS T—A,, SIN 7
which may be written
(°—a,,)tg’r—4a,,
(@y.— Ayal 1) 4/1 tg" age r (17)
wherein & = 2 as in (16). From (17) the azimuth of the
plane of polarization can be determined, provided 7 be known.
Equation (16) is biquadratic and indicates that in a er ystal
there are four possible waves, of equal significance,—-two
reflected and two refracted waves,—which must be taken into
account in the general boundary conditions for the erystal.
The general equations (11), (12) and (14) for the magnetic
light vector on passage through the boundary between two
inactive, transparent crystal plates may therefore be written :'
gv
4 4
> A, cos 7, cos y, = > A’, cos 7’, cos wy’, (from (w),=(u),)
4
> A, sin y, = > A’, sin W’, (from (¢),=(),) (18)
4
= A, sin 7, cos y, = > A’, sin 7’, cos y’, (from (w),=(w),)
eH Me »# Men
4 A, sin 7,
>
(sin ¥. (@,, COS 7,—G,, SIN 7) +a,, COS Y,) =
ATS Sim en .
—*—__*(sin y',(#’,, cos7,—@’,, sin 7",) +.a',, cos ’x)
(tm (=) =(3),)
In the last equation of this set both sides of the equation
sin TAS sin 7’,
have been multiplied by the equality —— ee
k k
In the first three equations, the factors of the amplitudes,
A,..A,, are the direction cosines, J, m, nm, of the line of
vibration 7 with the axes 2’, y’, 2’; if the factors of the
amplitudes in the fourth equation be indicated by p, the
equations can be written in the abbreviated form,”
1G. Kirchhoff, Ges. Abhandlungen,. 367-370, 1882.
2A. Potier, Journ, Phys. (2), x, 300, 1891. P. Kaemmerer, N. J., Beil.
Bd. xx, 174, 190
1
4
>
1
168) FE. Wright—Transmission of Light through
S4.,= 5 4107
1 1
4 4
Ayn, = ¥ Alm!
> erga > ok (18a)
4 4
SA, = > Ain,
at 1
4 4
LAAs A’ p's
1 1
In case the crystal plate is surrounded by an isotropic
medium, these general equations become simpler; the index
ellipsoid for the isotropic medium is a sphere and its coeffi-
cients are @’,,—= @',,= @,,.—=q, anda’,,=a,,=a',,=0. For the
passage of light from the isotropic medium to the crystal plate,
there are, in general, one incident wave (I), one reflected wave
(Rt) and two refracted waves, W,, W, (fig. 2); the boundary
equations are, then,
Fig. 2.
I R
Wu; ~W,
D, cos 0, cos r, + D, cos 0, cos 7, = (E cos e—R cos p) cos 7
D, sin 0, +D, sin 0, = E sine+Rsinp
D, cos 0, sin7,+D, cos 0, sin 7, = (E cos «+R cos p) sin 7
sin 7,,. :
iD), 7 *[sin 0, (a,, cos 7,—a@,, sin7,)+4,, cos 0,]+
1
D SU 5 ; 3 ;
. 7p [sin 0,(a,, cos 7,—a@,, sin 7,) +a,, cos 0,|= (19)
2
(E sin e—R sin p) sin @ cos 7
wherein, for the incident wave (1), the reflected wave (R), the
faster refracted wave W, and the slower refracted wave W.,,
respectively, E, R, D,, D,, are the amplitudes; «¢, p, 6,, 6,, the
polarization azimuths; g,, g,, @,, d,, the normal velocities of
the wave; 7, 7—17, 7,, 7,, the angles of the wave normals with
Transparent Inactive Crystal Plates. 169
z'. In these equations 2, E, ¢, g, of the incident wave are
known ; also by calculation (equations (16) and (17)), 7,, 7, and
05:05 of the refracted waves; and 7, g, of the reflected wave;
unknowns are R, p of the reflected wave and DD, ot the
refracted waves W, Woe
In abbreviated form, corresponding to (18a), these equations
may be written :'
D/, +DJ, = (E cos e—R cos p) cos 7
Dm, +D,m, = E sin e+R cos p
Dy», +D,n, = (E cos e+ Ros p) sin z
Dp, +D,p, = (E sin e—R sin p) siné cost (19)
At the second boundary surface where the two refracted
waves emerge from the crystal plate into the isotropic medium,
two sets of boundary equations obtain, one for each refracted
wave, W,and W,. At this surface, there are for each incident
wave, W, and W.,, two reflected waves and one refracted wave
as indicated in fig. 2.
For the refracted wave W, the boundry conditions reduce to
D, cos 6, cos 7,+R’, cos p’, cos 7’, +R”, cos p", cos 7”, =
IDINCos) 0) cos) 7
‘ PW Ie 1 View ee Ti whe.
D, sin 6, +R’, sin p’, +R’, sin p”, ee
: D’ sin 0’.
Heaps aes ! if yak ,! Tse WS a 7 ae
D, cos 8, sin7, +R’, cos p’, sin 7’, +R’, cos p sine =
D’, cos 8’, sin ¢. (20)
SUD PAT os :
D, 7 | sin 8, (4,, cos 7,-a,, Sin 7,) +4,, Cos 3, | +
1
R’, sin 7!
1 =o ’ ‘ / = ! 2 I
ese | sin p, (@,, cos? —a@,, sin r,)+-a,, Cosi p,) +
1
R”, sin 7”
1 1 is etd : a7 Picante te
apn [sin p’, (a,, cos 7”,—-a,, sin 7”,) +a,, cos r’,) =
1
D’, sin 0’, cos @ sin 7.
wherein, for the incident wave W, the faster reflected wave
W.,, the slower reflected wave W,,, and the refracted wave WwW";
respectively, D,, R’, R”, D’, aie the amplitudes; 6,, p’,, p”, 0;
the polarization azimuths ; PT Pte a the inclination of the
wave normals with 2’; and I Gs Fy Yo the wave normal
velocities.
Similarly, for the slower refracted wave W, the boundary
equations are
D, cos 6, cos 7, +R’, cos p’, cos 7’, + R”, cos p”, cos 7”
De cos ‘yy cos 7
D, sin 6, +I’, sin p’, +R", sin p’, Ett eu)
D', sin 6’,
1P,. Kaemmerer, Neues Jahrb., Beil. Bd. xx, 176, 1905.
170 EL EL Wright—Transmission of Light through
D, cos 6, sin 7, +R’, cos p’, sin 2, +R”, cos p, sin 7”) = (21)
cos p, sin 7”, = IDE veos! a sin 2
Sankey ple ; .
De (sin 8, (4,, COS 7,—a,, Sin 7,)+4a,, cos oy) +
Vs ;
R 5 sin ae J, Sey 1 as 1 f ,
—2___—+*| sin p, (@,, cos 7’,—@,, Sin 7”) + @,, COBip’, | 4.
Yu
p sibel : ” ay wv beet)
R’, oR sin p”,(a,, cos 7”,—a,,sin 7”,)+ a,, Cos p”,. | =
2
D’, sin 0’, cos @ sin @.
-
/
These equations (19), (20), (21), agree with the fundamental
equations of Neuman, MacCullagh and Kirchhoff derived from
the mechanical theory of light. They are, however, exceed-
ingly complicated, and in their solution certain auxiliary geo-
metric and analytic relations are used which simplify and
facilitate the practical calculations considerably. The most
important of these aids are the index surface introduced by
MacCullagh ('), Potier’s (7) generalization of the Neumann-
MacCullagh relation, and the conception of the uniradial azi-
muth as given by MacOullagh(*) and Neumann.(‘)
The Newman-Mae Cullagh-Potier relation.
The index surface, whose radii vectors are proportional to
the reciprocal wave normal velocities or directly to the refrac-
tive indices for the direction of propagation, is best adapted to
Fig. 3.
present graphically the relations between refracted and re-
flected waves. Itis derived from the index ellipsoid in the same
manner that the ray surface is derived from Fresnel’s ellip-
soid. The index surface (1) of a crystal is the reciprocal of its
ray surface (2), just as the index ellipsoid (I) is the reciprocal
1J. MacCullagh, Trans. Roy. Irish Acad., xvii, 252, 1833.
* Jour. Phys. (2), x, 349, 1891.
3 Trans. Roy. Irish Acad., xviii, 31, 1837.
4 Berliner Akad. Abh., Math. Abt. 144, 1835; Pogg. Ann., xlii, 9, 1837.
Transparent Inactive Crystal Plates. 171
of Fresnel’s ellipsoid (Ff). Each point S of the ray surface (2)
defines a ray direction; the normal OQ to the tangent plane
SQ through § of the ray surface is then the radius vector of
the normal tu the wave producing the ray, 8. (Fig. 3.) The
extension of this wave normal vector to its reciprocal length
ON determines a point N on the index surface. The two points
N and § are said to be corresponding points, and the plane
NOS is normal to the polarization direction.
Similarly, a point p of the index ellipsoid (I) is the corre-
sponding point P of Fresnel’s ellipsoid (F), (fig. 4), if its radius
vector coincides in direction with the normal op’ to the tan-
gent plane Pp’ through P and is equal in length to the recip-
rocal of the normal Op’=g. The radius vector, OP repre-
sents a ray of velocity s (fig. 4) while the radius vector Op = Lis
g
the reciprocal of the corresponding wave normal velocity g. The
normal to the plane Pop is then the polar- rey,
ization direction. By obtaining the codr- a tk
dinates of such corresponding points on the
two ellipsoids (F) and (1), Potier discovered
a simple relation between the expressions
l,m, n, p, of equations (18a) which has
proved of great value in the solution of B
problems of reflection and refraction.
For the sake of simplicity, let the equa-
tion of Fresnel’s ellipsoid and the index
ellipsoid be referred to the principal axes;
Fresnel’s ellipsoid is then represented by
Fa eto; the index ellipsoid by
(22)
MWe w+ yy +e 2=1 (23)
If the codrdinates of a point P on Fresnel’s ellipsoid be 2°,
y°,, 2°, then the equation of the tangent planes through P is:
5 (ok ile or WOE ey) oe
(x x 1 Gas ats y yY Aa)ye, + (2 & (Fn )e =
The equations of the normal to this plane are
az Yy @
2) = e = eo (24)
By definition, the point p is common both to the normal and
the index surface and its codrdinates, 2,, y,, 2,, are readily
found by means of (22), (23), and (24), to be:
1720 EF. EB. Wright—Transmission of Light through
2 =O, ©
Oa ]xe, oy]y®, ; d2 2°,
Similarly it can be shown that
Fee) AS) Bll, OL ay ful (25a)
(ae) aie ees
This reciprocal relation of polar quadries obtains for all posi-
tions of the codrdinate system, as can be readily proved by
adopting general coérdinates in the above equations.’
oe 4 i :
In case two pairs of corresponding points be taken, p, P,
and p, P,, then, in general codrdinates, 2
gi! aie, p(s) f= (5
PO Out! a, ? D3 dy! y', FS aioe Ba
,/0 = f=(— = (2
27 Oa’ com > Y= ahh ? ona ai
The general form of 21=a,,v"+a,,y" + ,,2” +2a,,y'2' + 2a,,2'x'
+2a,,x'y'=1 is that of a homogeneous equation of the second
degree, from which it follows that
! ol , ol Tr ol Tg oelt . t ! ib pot
x, Ox’ ae Oy’ tia PE gt gy Y gH yg? 24 +
A +Yy'2',) ar a, (2,2", +2 @ ,) ar A, (2',Y'o ae wy’)
ol aol TREN Sos
=0(57) pee ay),* ee x) i
tat PET ae eRe SAW cee Bell's 8K) fF aati r lO
Ce YY -+e 2 ee FY DY , +22 He (26)
Fig, 5.
Y!
Pp
S
ao
3
!
».¢
K
1MacCullagh, Geometrical Propositions applied to the wave theory of
light, Trans. Roy. Irish Acad., xvi, pt. 2, 67; also xvii (1833); Coll. Works,
p. 20-22, 1880.
Transparent Inactive Crystal Plates. 173
To apply this relation, discovered by Potier, between two
pairs of corresponding points on the two ellipsoids (F) and (1),
it is necessary to obtain the codrdinates of the points. In the
stereographie projection (fig. 5), let y and P be the projections
of the two corresponding points p and P, Ky’ the wave front,
x'z’ the plane of incidence, N the wave normal, 7 the angle of
inclination of N with 2’, the azimuth of the plane of polari-
zation, and s the angle pOP (O being the center of the sphere).
The coordinates of p are then:
'—O Iyosd 1 G 7)
a Bee sin w, cos 7,
1
1
DOCS BY Coe (27)
1
' Ets ol ee :
z,=Op cos pz a sin y, sin 7,
1
and the codrdinates of P are
oe ees c Sal a feo
x'° =OP cos Pa' =OP (sin s, sin 7,—Ccos s, cos 7, sin y,)
y,=OP cos Py’=—OP cos s, cos y, (28)
z' =OP cos Pz’ =OP(sin s, cos 7,+¢os s, sin 7, sin y,)
Op" qs
But from fig. 4, OP= and equations (28) ean
cos POp' cos s,
be written:
x’ =9,(t7 s, sin 7, — cos 7, sin y,)
Y 49. COSY (28a)
2 =q,(tg7s, cos 7,+sin 7, sin y,)
In fig. 5, P is situated between N and p; in case P lies
beyond p, tg s, in (28a) changes sign and becomes negative.
If the sign + be placed before tg s,, therefore, all possible
relations are taken into account; for each particular case, the
proper sign must be determined.
On substituting these codrdinate values (27) (28a) in the
Potier relation (26) for two sets of corresponding points p,, P.,
P., P, of the waves W,,W, whose normals lie in the plane of
incidence az’, we obtain,
q : : : :
~ | sin y, cos 7, sin y, cos 7,—sin y, cos 7, tg s,sin7, +
1
cos , cos Y, +sin y, sin”, tg s, cos 7, +Sin y, sin”, sin W, sin 7, ]
q,
q,
[ sin y, cos7, Sin y, cosr,—sin y, cos 7, tg s, sin 7, +
cos Y, cos Y,+sin y, sin”, tgs, cos7r,+sin y, sin 7, sin y, sin 7, |
This equation may be rearranged to read
(7, —¢’,)[sin YW, sin YW, COS (7,—7,) + cos W, Cos v|— (29)
(g 1 tg $, Sin Word 2 tg s, Sin ,) sin (7,—7,)=0
Am. Jour. pets uEre SERIES, VoL. XX XI, No. 183.—Marcg, 1911.
1
174 FE. Wright—Transmission of Light through
This general relation of MacCullagh-Neumann-Potier exists
between any two of the four possible waves, W,, W,, W,, W,,
within a erystal plate for each of which the sine law
g, sin 7, q, Sin 7, qg, Sin 7,
SS Tc ae hg Sentara rh.
POT) Sete Mens Ses Nei) sin é
is valid. These values introduced into (29) give after division
by sin (7,—7,) the equation
sin (7,+7,)[sin y, sin y, cos (7,—7,)+cos y, cos y,]— (29a)
sin’ 7, tg s, sin y,—sin’ 7, tg s, sin y,=0
Six different equations of this general form are possible, as six
combinations of two can be obtained from the four different
waves.
Equation (29a) can be simplified by substituting for ty s, an
expression containing g,, 7,, ¥,, and three constants, @,,, d,.) Us.)
of the index ellipsoid. In fig. 4, the coordinates of P are
rope BIN oI
ah al (e (equation (25@)) and the length
d1\? BNE Ol\2
Oz
Accordingly
Op' q
PO '— a —— u
cos J) =COS S, OP Vy nie a O1L\? (30)
V (5.),+ (5;),+ (a)
The direction cosines of the radius vector OP are propor-
tional to the codrdinates of P and therefore from (29) and (29a)
ol
Cos baaae ee (=). _tg s, sin r,—cos 7, sin y,
COS Py) Tn ole ae —cos tp,
(33),
from which
(5 ) =(3,) —cas yy,
Oy), \dx/, tg s, sin r,—cos 7, sin y,
Similarly (81)
OLN | tg s, cos7r,+sin 7, sin y,
& a \e ,tg Ss, sin 7,—cos7 sin y,
On substituting these values from (31) in (30) we find
Lee. q%
Se I Le
/1+tg’s, (5) Vitis’ 8,
“/, tg 8, sin 7,—cos 7, sin y,
COs S$, =
Transparent Inactive Crystal Plates. 175
or tg s, sin 7, = ~(5) +cos 7, sin y,
AM),
ol / /
But (Fe) Oa Cb Yb A
which from (27)
il : : ;
= @ ( —d,, cosr,siny,—d,, cos ¥, + a@,, sm 7, sin )
1
7 1
Accordingly
2 S te oe 2
Fes (97, —4@,,)cos ”, sin ¥,—a,, cosy, +a,, sin 7, sin y, (*) (32)
1
q°, sin 7,
On eliminating tg s from (29a) by means of (32) we find
sin (r,+7,)[sin y, sin y, cos (7,—7,) + cos y, cos y,]+
sin 7, sin Wy,
q
sin 7, sin y,
q,
which on rearrangement becomes
[a,,—7',) cosr, sin y,—4,, sin 7, sin W,+a,, cos y,]+
(a,,— q,)° cos 7, sin W,—4,, Sin 7, Sin Y,+a,, cos y,]=0
1This expression was first derived by P. Kaemmerer (Neues Jahrb., Beil.
Bd. xx, 206, 1905), though by a method different from the above.
2From the equations (80) and (81) the following relations can also be
derived:
—cos P= It (5) = 1 —@i2 COS 7; SIN Y;—Aeo COS J, + G13 SiN 7 Sin a)
qi \dy/»
2
—a
or tg y= Osim 2aa Be (82a)
G12 COS 71 —Ao3 SIN 1}
an equation identical with (17).
— %
mee ae Vixntg s,
0z ; tg si cos7; +sin 7; sin yp,
Also
—@13 COS 7; SiN W;— 3 COS 1 +(As3—Q"1) SiN 71 Sin W, (32b)
@*1 Cos 1,
an expression for fg s, which is apparently novel. On equating (82) and
(320) we find
a 12 COS 7; —Ao3 SiN 1;
tg i= 5 a - D)
@?1— M11 COS’; —G33 Sin? 7; + 2ai3 SiN 7; COS 11 )
From (82a) and (32c), we have
(q?1 —@22)(q?1 — G11 COS? 71] — M35 Sin? 7; +2 a3 SiN 1; COS T;)
=(die COS 7; —Ag3 Sin 71)?
an expression free from wp and identical with (16). .
or tg =
176 FL EB. Wright—Transmission of Light through
cos 7, cosy, sin 7, cos w,+ cos 7, cos , sin 7, cos y, +
sin 7, sin W,
j [sin y,(a,, cos 7,—a,, sin 7,)+a@,, cos ,]+ (33)
q,
sin 7, sin ; f
ea a [sin w, (@,, CoS 7,—@,, Sin 7,)+a,, cos w,] = 0
To i
an equation, which, like 18¢, can be written in the abbreviated
form
Ln tln,+p,m,+p,m, = 0 (33a)
This equation is the general Potier relation’ and is applicable
to any two of the four possible waves within the crystal.
Uniradial azimuths.
At the boundary surface of a crystal plate with an envelop-
ing isotropic medium, an incident plane polarized, monochro-
matic light wave furnishes, in general, one reflected wave in the
isotropic medium and two refracted waves, W,, W,, within the
erystal. The directions and azimuths of the two refracted
waves are definitely fixed by equations (16) and (17) and a
rotation of the plane of polarization of the incident wave can
produce a change in the amplitudes only of the two refracted
waves. Fora certain value of the azimuth, the amplitude of
either W, or W, becomes zero, and but one refracted wave is
transmitted. Such azimuths, e,, of the plane of polarization
of the incident wave, for which only one refracted wave
results, are called uniradial azimuths, and were first inves-
tigated by MacOullagh* and Neumann.’ For D, = 0 in equa-
tion (19) we find
(a) (E cos e,—R cos p) cosz ==)
(6) Esin e, +R sin p == DN simso),
(c) (E cos «, +R cos p) sin 7. = D) cos 0, sin 7, |. (34)
(d) (E sin e,—R sin p) sin? cos? =
D, sinv «
1 1 = a
eee [sin 0,(@,, cos 7, —a,, sin 7,)+4a,, cos 0,]
L
The last equation of this set can be readily reduced by means
of (32) to the form
(d’) (EK sin e,—R sin p) sin 7 cos7 =
D, sin*’r,(cot 7, sin 0,—¢g s,)
By multiplying the first of these equations with sin ?, the third
with cos 7 and adding; also the second with cos 7 sin 2, and
adding to the fourth, we obtain
1 Potier, Jour. de Phys. (2), x, 352, 1891.
2Trans. Roy. Irish Acad., xviii, 31, 1837. Collected Works, p. 110, 1880.
2 Berliner Akad. Abh., Math. Abt. 144, 1835; Poge. Ann., xlii, 9, 1837.
Transparent Inactive Crystal Plates. diving
. (a) E cos «,(2 cos ¢ sin 7) = D, cos 0, sin (¢+7,)
(6) Esin «(2 cos¢sinz)=
D, (sin 0, sin 7 cos 7+sin’ 7 (cot 7, sin 0, —¢g s,)
On division of (0) by (a) 4
sin 0,(sin 7 cos7+sin r, cos 7,)--sin’ 7, tg s,
cos 0, sin(¢+7,)
ge=
sin’ 7, tg s,
or tg «, = tg 6, cos (t—7,) - ane an Ol
1 1
(35a)
a
sin 7, tg S,
cos 0, sin(#+7,)
Similarly, tg «, = tg 0, cos(t—r,) —
By means of these formulas the uniradial azimuths for the
refracted waves W, and W, can be calculated. At the second
boundary surface of the crystal plate, the refracted wave W,
produces two reflected waves W,,, W,, and one emergent wave
W’.. (fig. 2). To caleulate the azimuth of the plane of polari-
zation of this emergent wave, the relations of -Potier are
important. The general boundary conditions for this surface
and wave W, are defined by equations (20), which, after the
manner of (18a) can be written in the abbreviated form:
DL © BP, = RB’. =D’ cos 0! cosé
Dim,+ Rm’ + Rm’ = De sin o”,
Dan, + Rin’, + Rn’, = D’, cos 0", sin? (20a)
Dp, + Rp’, + R’ p’, = D’, sin 0’, sin 7 cos 7
On multiplying the first of these equations by n,, the second
by p,, the third by Z,, the fourth by m,, and adding, we find
D,(n,J,+m,p,+1,n,+m,p,) +R’ (nv +pm',+1,n',+m,p',) +
R! (fn, +m, p",+4,m"_ +m,p",) =
D’,(n, cos 4’, cos i+p, sin 0’, +0, cos 0’, sin ¢+m, sin 0’ sin 7 cos @)
In this equation the coefiicients of D, R’, R’, are=0 by
virtue of the Potier relation (83a), and as the amplitude D’ is
not in general zero, the equation reduces to
n, CoS 7+/, sin @
Pp, +m, Sin 7 Cosz
On replacing 7,, Z,,9,, m, in this expression by their respective
tg Os =
values from (19), we obtain
lg W =_—
cos 0, sin 7, cos 7+cos 0, cos 7, sin 7 (36)
Ringe 5 : ‘ vote ;
P [sin 0,(@,, cos7,—a,, sin 7,) + @,, cos 0,] + sind, sin @ cos ¢
2
178 EB. Wright—Transmission of Light through
This Bapree eH can be simplified, as was (84), by the intro-
duction of tg s,
cos 0, sin(? +7,)
sin* 7,(cot 7, sin 0,—¢g s,)+ sin 0, sin Z cos 7
tg O” =—
cos 0, sin(¢+7,)
sin 0, sin(¢+7,) cos (¢—7,)— sin’ ”, tg s,
(36a)
or tg 0" =—
On comparing this relation with (350), it is evident that
1
Te
g 1 tg €,
oe = 6 aE 90° (37)
also Of Nemo Oe
This apparently new and important relation greatly simpli-
fies the labor of calculating the azimuths of the planes of
polarization of waves transmitted through a crystal plate. In
form it is similar to the relation deduced by Potier,’ that in
case a wave W, within a crystal plate emerges into an isotropic
medium, the emergent wave is polarized at right angles to that
wave which, entering the crystal plate in the opposite direc-
tion, produces the so-called “Hilfswelle W’” of W’. The
above relation states that the azimuth of the plane of polariza-
tion of the emergent wave W’, from W,, is at right angles to
the uniradial azimuth e, of the wave W,. To calculate the
azimuths of the emergent waves W’,, W’,, it is only necessary,
therefore, to calculate the uniradial azimuths e,, e, of the inci-
dent waves which produce the refracted waves W, and W,,.
Uniaxial Crystals.
In the preceding pages the formulas for the transmission of
light through crystal plates have been developed for the most
general case, that of biaxial crystals. When applied to uni-
axial plates, these formulas become somewhat simpler, and
deserve brief consideration as they will be used in the observa-
tional part of this paper. The equation of the index surface
for uniaxial crystals referred to general codrdinates is
[0° (ae? +4" +2’) —1][@,,2" an U e +, ze 14-20, WV 2 ate
2a, ge! +2a,,0'y' —1]=0.
If, as usual, the plane of incidence be the «’ 2’ plane, (y’=0),
and the zg’ axis the normal to the plate, the positive direction
of z' being within the crystal plate, this equation can be written
1 Journ. de Phys. (2), x, 354, 1891.
2H. HE, Neumann, Berliner Akad. Abh., Math. Abt., 1835.
Transparent Inactive Crystal Plates. 179
[o°(a’? +2") —1][a, ,v" +a,,2° + 2a,,2'x’—1]=0. (38)
In this formula w’ and 2’ can, by virtue of the sine law, be
readily expressed in polar coérdinates; if 7 be the angle of
incidence and 7 the angle of refraction and m, the refractive
index of the isotropic medium, then v =n, sin 2, and
sin @ :
Zo== aa . With these values (38) reduces to
WL
[o’n,” sin? ¢ (1 +ég’r) —tg’r][(@,,2. sin® ¢—1)tg’r +
2a,,2,' Sin” ttgr+a,,n, sin? i]=0, (38a)
From the first half of this equation (88a)
sin 7,=7, O Sin 2@.
To evaluate the coefficients of tg 7 in the second half of the
equation (38a), let the plane @’ y’ in fig. 6 be the boundary
surface of the crystal plate; a’ 2’, the plane of incidence, the
positive direction of 2’ being on the crystal side of the bound-
ary surface; «, y, 2, the principal ellipsoidal axes of the erys-
tal; @ the polar angle zz’, and », the azimuth of the principal
plane 22’; let also the angles of inclination of the wave normals,
Q., Q., with the 2’ axis be Q,2’=7, Q.2’=7.; with the 2 axis,
be Q.2=¢,, Q.2=¢.. In this case the direction cosines of wv’,
y', 2 with x, y, 2, are respectively
P, = — Cos 8 cos w Pp, = Sino P, = sin 6 cos w
7, = — cos sin w 7, = — Cos w q7, = sin 0 sin w
ri sin a) ii, == GOS (uy
also, inequations|(9)i@: = er. nbs )6' ce = 07,
180 Ff. EL Wright—Transmission of Light through
Substituting these values in equation (9), we obtain the
usual equations
a,, =e +{o°—e’) sin’ 6 cos’ w
A,,=e +(0°—e’*) sin’ 6 sin® w
a@,,=€ sin* 6 + 0° cos’ 6 (39)
,,=(0°—e*) cos @ sin @ sin w
d,,=(0°—e*) cos 6 sin 6 cos w
a,,=(0*—e’) sin’ @ cos w sin
and the coefficients of tg 7 in the second half of (88) become
@,,%) Sin* i—1=n,° sin’ 7 [e’+ (0’—e’) sin? 6 cos’ w]—1
2a,,m0° sin® 4=2n," sin’ 7 (o"—e") cos sin Ocosw (40)
U,,%) Sin® t=n, sin* 7 (e’ sin” 6+ 0? cos? 6). <
From equations (88a) and 40), 7, for the extraordinary wave
can be calculated. If n,=1, as is practically the case when
the crystal plate is surrounded by air, equation (38a) can be
written in the following form, which is logarithmically con-
venient :
sin 7,=0 sin 7; (41)
uf 1
Bcos wo + Y B’ cos’ o + c( ; sat A cos? w — ¢)
sin? ¢
tg — 1
e — A cos?’ wo — —,.
sin® 7
wherein A = (e’—0o’) sin’ 0
B = (e’—o’) sin @ cos 6
C = e’ sin’ 6 + 0’ cos’ 6.
To find the azimuths 6,, 6, of the planes of polarization of
the refracted waves W,, W,, fig. 6.is again useful. In the
spherical triangle Q, 2 2’, the relation obtains
sin 7, cot 6 — cos 7, cos w
cot 0, = a (42a)
while in the spherical triangle Q, 2 2’
iq bee cos 7, COS w — sin r, cot 6 (428)
sin w
The uniradial azimuths e, and e, are calculated from equa-
tions (35a). For the ordinary wave the wave normal and ray
direction coincide and the angle s,—0.
Accordingly
tg €,==tg 9, cos (t—1,). (43)
In the analogous expression for #9 €,,
sin’? 7, tg 8,
cos 0, sin (¢+7,) ee)
tq 8, occurs but can be expressed in terms of known angles.’
1 MacCullagh, Coll. Works, 1880. Trans. Roy. Irish Acad., xvii, 1833.
Pockels, F., Lehrbuch der Kristalloptik, 194-195, 1906.
tg «, = tg 9, cos (t—r.) —
Transparent Inactive Crystal Plates. 181
In uniaxial crystals the usual formula for tg s, is
2 2
is = a cos ¢, sin ¢, (a)
where ¢, is the angle Q,.z of fig. 6. From the spherical tri-
angle Q, 2 2’, fig. 6,
cos 7, sin 0, — cot w cos 0, |
(2)
cot ¢, =
sin 7,
cos 0,
also cot ¢. = — (cot 6 cos 7, + CoS w sin ”,). (0’)
sin w
Furthermore, in the principal section through Q, and z
Je = 0 cos’ d + e’ sin’ ¢,
from which expression, we find (c)
e—o’ ., ; O° 4 sin’ 7”, sin (7,—7,) sin (7,+7,)
- Sino, == fo = ws :
Oe $e Yo sin’? 7, sin’ 7,
By means of the three equations (a), (0), (c), equation (44)
becomes
sin (7,—7,) sin (7, +7.) (cot o—cos r, tg 0.)
sin (¢+7.) sin 7, (44a)
tg «, = tg 9, cos (i—r,) +
or from equations (a), (0’), (¢)
tg «. = tg 9, cos (i—r,.) +
sin (7,—7,) sin (7,.+7,)(cot 8 cos r,+ Cos w sin 7.)
sin (¢+7,) SIN w (44d)
Having thus found e, and e¢,, the azimuths 6’, and 6’, are
readily obtained by the use of equations (37).
0’, =€.+90° 0’, =e+90- (45)
e
Isotropic Plates.
In the case of isotropic plates, the index ellipsoid reduces
to a sphere and the constants of the equation become
a,, = ,, = a. — Y
Ay5 = A, aa a, = 0
Equations (16), (85a), (86a), then reduce (if the surrounding
medium be air g,=1)
sin @
VW
(0) tg «, = tg 0, cos (t — 1)
(a) Sin 7) 19 7sin? =
(0) tg 0, = 00h:
cos (t—7) (46)
182. Fk. EL Wright—Transmission of Light through
In these last two equations, (4) and (¢), the azimuth 6, may
assume any value, since the structure of isotropic substances
does not prescribe definite planes of polarization for transmitted
waves, as do anisotropic substances; but if 6, be once given,
6, is then = 6, + 90°
and the last equation, (¢), may be written
tg 6, ig €,
ey cos (t¢—7) cos (i— 7)? (46c’)
From this formula, the angle 8’ can be caleulated, provided
e,, «@ and 7 be given. The difference (e,—8’,) is.then the
amount of rotation which the plane of polarization of incident,
monochromatic light suffers on transmission through the
isotropic plate.
In case the light wave passes through several plates,
cemented together as in a thin section mount where n, is the
refractive index of the object glass, , that of the Canada
balsam, and , that of the cover slip, an incident wave 2
; similarly,
becomes 7, in the object glass, where sin 7, =~
nN,
7, and 7, are the angles of refraction in m, and n, and can be
calculated by the general sine formula above. From formula
(460) and (46c) it is evident that the total rotation of the plane
of polarization of a transmitted wave under these conditions is
cot 0’ = cot € cos(t—r,) cos(7,—7,) cos(7,—7r,) cos(¢—7,)
Summary.—In the foregoing pages the formulas have been
developed which are especially useful in a consideration of the
phenomena observed on mounted crystal plates in convergent
polarized light. In this discussion, the effects of the plates on
reflected light waves have not been treated in detail, nor has a
study been made of the relative amplitudes of the reflected
and refracted waves; attention has been directed rather to the
effects of transparent, inactive plates on the planes of polariza-
tion of transmitted light. In the calculation of these effects,
four steps are necessary; (1) if. the angle of incidence 7 of the
entering light wave be given, the angles of refraction 7,, 7, of
the two transmitted waves are found by means of formula
(16) in the case of biaxial plates, or by (41) for uniaxial plates,
or by (46a) for the single transmitted wave in isotropic plates.
(2) The azimuths of the planes of polarization of the two
refracted waves are then found by use of equations (17) for
biaxial plates, or (42) for uniaxial plates. In the case of iso-
tropic plates the plane of polarization of transmitted waves
may have any azimuth, so far as such azimuths are dependent
on the structure of the material. (3) Having given the angle of
Transparent Inactive Crystal Plates. 183
refraction and the azimuth of the plane of polarization of a
trausmitted wave, the azimuth of the plane of polarization of
the incident wave which produced it is obtained by use of equa-
tions (35) for biaxial plates, (48) or (44) for uniaxial plates, and
(460) for isotropic plates. (4) To find the azimuth of the plane
of polarization of the emergent wave, provided that of the
incident wave which produced the refracted wave be known,
equation (37) is useful. This last equation, which is apparently
new, states that the azimuth of the plane of polarization of
an emergent wave 0’,, resulting from the refracted wave W.,, is
90° from the uniradial azimuth of the incident wave e, which ~
produced the refracted wave W,.
A detailed discussion of the above formulas is deemed
unnecessary in this summary, as they are in large measure
standard and the effects of the different factors will appear
more clearly in the discussion of the data of observation.
In the development of these formulas, no account has been
taken of the effects of surface films on the rotation of the
planes of polarization of transmitted waves. These films have
been shown by P. Drude’ and others to be occasionally of great
influence, especially on plates which have been highly polished,
while on freshly cleaved plates they are practically absent.
The observations listed in the following pages were made
largely on cleavage plates, which, however, were usually ex-
posed for a month or more before the observations were finished
and may have accordingly suffered some deterioration.
Parr 2.
Observations.
Apparatus.—All observations recorded below were made in
sodium light, the crystal plate being mounted on a universal
stage on the new model petrographic microscope recently
described by the writer.’ To insure accuracy, the microscope
was carefully adjusted and its adjustment tested at intervals in
the course of the measurements. The nicol prisms were
of the square end Glan-Thompson type and were crossed by
pointing the microscope, from which all lenses had been
removed, directly toward the sun whose rays are parallel and
so intense that a rotation of less than 1’ of are from the posi-
tion of exact crossing of the nicols is readily discerned. By
means of the iris diaphragms the sun’s rays were sent through
the microscope centrally so that no rotatory effect of the nicol
surfaces on the planes of polarization of the transmitted waves
was possible. The ordinary type of nicol prism with oblique
1 Wied. Ann., xxxvi, 532, 865, 1888; xxxviii, 265, 1889; xliii, 146, 1891.
? This Journal (4), xxix, 407-414, 1910. P
184 OE. EL Wright— Transmission of Light through
ends was first used, but was soon discarded because of the
effect of its oblique surfaces on the plane of polarization of the
transmitted waves. For exact work in extinction angles, the
ordinary type of nicol prism is much inferior to the Glan-
Thompson type with square ends. Having thus crossed the
nicols accurately, the crosshairs of the ocular were adjusted by
using the ocular and Bertrand lens as a microscope and focus-
ing on a mounted anhydrite cleavage plate through which par-
allel sun’s rays were passed centrally. Here again the sun’s
rays are so intense that the position of total extinction of the
anhydrite plate can readily be fixed within 1’ of are. By
means of the anhydrite plate which extinguishes parallel with
its cleavage edges, the principal sections of the nicols and the
ocular crosshairs were brought to coincidence. The universal
stage was then attached to the microscope stage and its hori-
zontal axis of rotation brought to coincidence with the hori-
zontal crosshair of the ocular, by use of the lines engraved on
the glass disk of the universal stage. This glass disk, together
with its supporting ring, was then remoyed and in its place a
second ring of precisely the same dimensions substituted, on
which a strip of thin glass plate was cemented, and to which
in turn one corner of the crystal plate was cemented, the glass
plate serving merely as a support for the erystal plate whose
major part was left free and exposed on both sides to air.
The surface of the crystal plate was then brought to approxi-
mate parallelism with the horizontal circle of the universal
stage ; it was adjusted to exact parallelism by viewing, through
a mounted telescope, the image of a distant light source as
reflected from the surface of the crystal plate. The horizontal
circle H, of the universal stage’ was then rotated and the erys-
tal plate tilted and turned by means of the horizontal circle H,
and the vertical circle V, until the reflected image remained
stationary on rotation of H,. The circles on the universal
stage could be read to 5’ by means of the vernier, while on the
microscope stage the vernier intervals were 3’. In neither
case, however, were the lines on the circles and verniers suffi-
ciently fine to insure greater accuracy in reading than the 3’ or
5’ intervals on the vernier. In actual work each position of
total extinction was determined 10 times and the average
taken. On sharp extinctions it was found that the different
settings were usually within 10’ of the average.
In the earliest preparations measured, the positions of total
extinction were determined by use of the bi-quartz wedge
plate,’ but the fact that, in making the observations with this
plate, it was necessary to use the objective and ocular, the
glass surfaces of which in turn influence the plane of polar-
1See page 186 below. ? This Journal (4), xxvi, 391, 1908.
Transparent Inactive Crystal Plates. 185
ization of transmitted waves, was sufficient reason to discard it.
In the final arrangement adopted, no glass surfaces intervened
between the nicols and the erystal plate. An enlarged image
of the plate was obtained by means of a weakly magnifying
microscope consisting of the Bertrand lens and ocular, above
the upper nicol.
Intense sodium light flame.—To increase the intensity of
the sodium light flame, and with it the accuracy of the observa-
tions, an arrangement was adopted which in practice has proved
entirely satisfactory. A 25° platinum crucible was filled with
a mixture of sodium chloride and sodium carbonate and
heated over a Bunsen burner, a special mounting of thick
platinum wire having been made for the
erucible as indicated in the diagram. ), in which the axial bars are drawn
for the two positions of the extinguishing plane of the upper
nicol (—10° and +15° ) as indicated by the dotted lines. The
1 This Journal (4), xxix, 423, 1910.
Transparent Inactive Crystal Plates. 205
observations were made by using the cross grating ocular as
shown in the microphotograph fig. 15. The observed codrdi-
nated values were reduced to their angular equivalents by use
of the apertometer and these in turn reduced to the corre-
sponding erystal angles by means of the sine formula and the
refractive index 8. The use of the refractive index 8 for all
direction introduces an error, but experience has shown that
this error is not great and in general may be disregarded.
Points were located as accurately as possible along each
axial bar and then plotted in projection (indicated by small
circles, figs. 14a, 146). Although the axial bars were not
perfectly sharp they were well detined and the points were
taken along the central line of the bar, the position of each
point being determinable to within about 1°, or less for certain
positions. In fig. 14a, the results which were obtained from
an unmounted cleavage plate are represented ; in fig. 140, the
interference figure is that from the same plate mounted in
Canada balsam between cover glass and object glass. In each
of these figures, the positions of the line of vibration were
determined graphically, both by the method of Professor
Becke (indicated by small crosses) and by that of the writer
(indicated by small circles). A comparison of the relative
positions of these small circles and crosses relative to the dot-
ted line which represents the position of extmguishing plane
of the upper nicol shows that in a few instances the points
as determined by Professor Becke’s method are slightly
more accurate than the equivalent points of the writer’s
method; in the majority of instances, however, the small
circles are more nearly correct than the small crosses.
As a general] rule, it may be stated that the order of accuracy
of the two methods is about the same, the writer’s method
having the single advantage of greater simplicity.
A critical comparison of the results of observation on
mounted flakes with those on unmounted flakes show clearly
the effect of rotation by the glass surface, causing the axial
bars and axes to shift slightly, so that the direct reading of the
optic axial angle is not quite the same in the two cases. The
difference is not great, but it is noticeable, and is sufficient to
make it advisable to use unmounted plates wherever possible, in
optic axial measurements, if results of the highest accuracy are
desired. Ordinarily, however, this precaution is unnecessary,
since such accuracy is not required.
A rotation of the crossed nicols through 90° also generally
produces a slight shift of the axial bars from mounted plates,
as indicated by fig. 16, which is a direct record to scale of the
observed phenomena. In each case the points along the cen-
tral line of the axial bar were plotted. The position of this
Am. JOUR. Sch SE oree SERIES, VoL. XX XI, No. 1838.—Marcgu, 1911.
1
206 =F. EL Wright—Transmission of Light through
central line for an angle of rotation of 15° of the crossed nicols
is indicated by the curve I, fig. 16; it sposition for an angle of
rotation of 105° is shown by curve II. These two curves do
not coincide, and although such measurements cannot be made
very accurately, they show that a rotation of the crossed nicols
Fie. 16.
causes a slight shift of the axial bars of the interference figure
of a mounted crystal plate. The amount of shifting rarely
exceeds several degrees and is usually less, but it is often sufii-
cient to be perceptible and shows the importance of referring
the data, when plotting, to the correct position of the extin-
guishing plane of the upper nicol. It is, therefore, not imma-
terial which one of the principal nicol sections be chosen. If
the observations themselves were of a higher order of accu-
racy, this fact would be a serious objection to Professor Becke’s
method.
Anhydrite.—A series of observations (figs. 17a, 6) on a cleay-
age plate of anhydrite, unmounted (17a) and mounted (176), cor-
roborates the conclusions stated in the last paragraph. The
degree of accuracy of the two methods in question is about the
same here as in muscovite. A rotation of the crossed nicols
through 90° also produced a slight shift of the axial bars on
mounted plates, as in muscovite, and it is important, therefore,
that the plotting be done with reference to the correct prin-
cipal nicol section.
Transparent Inactive Crystal Plates. 207
Fie. 17a.
Fie. 170.
208 EE. Wright—Transmission of Light through
A device to aid in the graphical solution of optical problems
involving the use of the stereographic projection.
In the measurement of optic axial angles in convergent polar-
ized light,’ and also in all measurements by means of the uni-
versal stage methods, the stereographie projection plat of
Prof. Wulff has proved a useful and necessary adjunct, the
angular values of observation being plotted directly on thin
transparent paper placed above the plat and held in the center
by means of a needle. This needle, however, is not entirely
satisfactory, since it does not hold its place rigidly and tends
thereby to injure the stereographic plat below. To overcome
this dithculty the writer has constructed the device of fig 18
Fic. 18.
C D
(one-eighth actual size). A heavy brass bar fits into two end
blocks of brass, A and B; at its center a small hollow brass rod,
C, containing a needle backed by a spring is introduced. By
this device the needle is rigidly supported in a vertical posi-
tion, and as the distance between the end blocks A and B is
44, there is more then sufficient space available for the pro-
jection plat and the overlying drawing. The writer has used
this device for several years and has found it satistactory and
a time saver.”
Summary.
Minerals are determined under the microscope by the effects
they produce on transmitted light waves. Plane polarized
light waves are ordinarily used and examinations are made
1 For determining the Mallard constant of the microsope, whichis required
in the measurement of optic axial angles by means of the microscope, Dr. J.
S. Flett of London uses a Zeiss Abbe apertometer. His method is simple
and accurate and is superior to any method yet suggested. He introduces
the micrometer scale in the ocular as usual and then determines the divi-
sions covered by the different angles of the apertometer. Since with this
device any angle can be instantly set off, an objective can be calibrated
rapidly for all possible angles within the field of vision, and an empirical,
correct table prepared which is independent of the Mallard formula, thus
obviating all errors due to a lack of correction in the objective lenses.
* Recently, Prof. Nikitin has had constructed a graduated porcelain hemi-
sphere (made by R. Fuess, Steglitz, Berlin, Germany) which the writer has
found very satisfactory in optic axial angle projections and slightly more
accurate than the projection plats. chiefly because of its lack of distortion
toward the margin and consequent acute angled intersections of great circles.
This hemisphere has the advantage of serving as amodel in the study of
optical phenomena and is a useful piece of apparatus for the petrological
laboratory.
Transparent Inactive Crystal Plates. 209
partly with and partly without the aid of the upper nicol (ana-
lyzer). In anisotropic erystals the planes of polarization of
light waves, transmitted along a given direction within the
erystal, are prescribed by the crystal structure. On entering
or emerging from a crystal plate, plane polarized light waves
transmitted obliquely usually suffer a slight rotation of the
azimuth of their plane of polarization. The amount of this
rotation is rarely more than a few degrees. In practical micro-
scope work but little attention has been given to this
phenomenon, but in accurate work it is a factor which must
be considered.
In the foregoing pages the attempt has been made in Part
1 to present, in terms of the electromagnetic theory of light,
the general mathematical treatment of the transmission ot
light waves through a transparent inactive crystal plate, spe-
cial attention being given to the rotatory effects of the boun-
dary surfaces of the crystal plate on the plane of polarization
of a transmitted wave. This problem was first solved in 1835
by J. MacCullagh and also by F. E. Neumann; since their time
a number of investigators have made important contribu-
tions to its solution. Interest, however, has centered chiefly in
the reflexion of light waves by erystal surfaces and no con-
nected presentation of the mathematics covermg the phenom-
ena of refraction in crystal plates appears to have been made.
This has been essayed in Part 1. The greater part of the
ground covered therein is familiar, but several of the formu-
las derived appear to be new, notably (326) and (87). Of
these (87) is important and states that the uniradial azimuths
of the plane of polarization of the emergent waves W’, and W’,
are 90° from the uniradial azimuths of the entering waves
whieh, on refraction, produce the waves W, and W,. In other
words, the positions of extinction on emergence for either one
of the two possible refracted waves, W, or W,, resulting from
a single plane polarized light wave, incident at the surface of
a crystal plate, are precisely 90° apart. The positions of
extinction for the two waves do not, however, coincide and
there is in general, therefore, no position of total extinction
for waves transmitted obliquely through a crystal plate.
Both theory and the observations of Part 2 show that as a
general rule, a uniradial, plane polarized light wave, after
transmission through a bare crystal plate (preferably a cleav-
age plate so that the disturbing effects of surface films caused
by polishing are not serious), is still plane polarized, but its
plane of polarization has suffered a slight rotation depending
on the direction of transmission, and if examined under crossed
nicols does not appear perfectly dark in consequence. In thin
crystal plates the two refracted waves W, and W, overlap to a
210 Ff. EB. Wright—Transmission of Light through
large extent and there is no position of total extinction for the
tilted crystal plate even if the upper nicol be rotated alone.
In general it may be stated that from an incident plane polar-
ized wave two refracted waves are formed, which on emerg-
ence from the plate are each still plane polarized, but their
planes of polarization are not precisely 90° apart. The result-
ant light as observed through the analyzer is consequently
elliptically polarized and there is no possible position of total
extinction of the plate, but rather a region of minimum illumi-
nation which may extend over several degrees.
These relations have an important bearing on methods based
on the determination of the positions of extinction of obliquely
transmitted waves, and preclude at once a high order of accu-
racy in the measurements. If the observed crystal plates are
mounted in Canada balsam, the rotatory influence of the sur-
faces of the glass and Canada balsam mount enter the problem
and tend to complicate the phenomena still further.
The measurements of Part 2 show: (1) That a tilted glass
plate may rotate the plane polarization of a transmitted plane
polarized light wave several degrees, and that the amount of
rotation increases with the angle of tilting; (2) that the
observed uniradial azimuths of tilted cleavage plates of calcite
agree closely with the calculated values; (8) that for the central
areas of tilted plates of calcite, nephelite, muscovite, and ara-
gonite, there are no positions of total extinction. It settings
be made at the apparently darkest positions of the plate during
the rotation of the microscope stage, these positions are often
several degrees from 90° apart, and if the observed azimuths
of the plane of polarization be taken as the azimuth of the
refracted waves within the crystal, errors of several degrees
are easily possible. (4) An obliquely transmitted wave will
be extinguished provided its direction of vibration after emerg-
ence is contained in the extinguishing plane of the analyzer.
The direction of vibration of an observed dark point on the
axial bar of an interference figure is therefore the line of
intersection of the extinguishing plane of the upper nicol with
the polar plane of the given point. This construction, sug-
gested by the writer, does not take into consideration the rotatory
effects of the surfaces of crystal plate and glass mount, and is
accordingly only an approximate method. Prof. Becke has
suggested another method, which is, in effect, to find the inter-
section of the polar plane with the great circle in stereo-
graphic projection, which is tangent to a line parallel with the
principal section of one of the nicols. The points obtained by
Prof. Becke’s method are slightly different from those obtained
by the writer’s method, but not sufficiently different to affect
the degree of approximation obtainable by such methods. In
Transparent Inactive Crystal Plates. 211
principle, however, the two methods are fundamentally differ-
ent, and a detailed discussion, together with a series of meas-
urements on interference figures of muscovite and anhydrate,
indicate the general validity of the principle on which the
method proposed by the writer is based; in this method the
rotatory effects of all boundary surfaces are disregarded and for
this reason the results obtained by its use are only approxi-
mately correct.
Several devices are described which have been found ser-
viceable in connection with this work: (1) An apparatus for
securing an intense and constant sodium light. (2) A simple
and accurate method for adjusting the petrographic micro-
scope. (8) A device to aid in the work with the stereo-
graphic projection plat.
Geophysical Laboratory,
Carnegie Institution of Washington,
Washington, D. C., November, 1910.
212 Gooch and Boynton—Estimation of Barium
Art. XX.—The Separation and Estimation of Barium
Associated with Calcium and Magnesium, by the Action of
Acetyl Chloride in Acetone Upon the Mixed Chlorides ; by
F. A. Goocs and O. N. Boynton.
[Contributions from the Kent Chemical Laboratory of Yale Univ.—cexviii.]
In former papers from this laboratory* it has been shown
that certain chlorides may be quantitatively precipitated for
purposes of analysis by treating their water solutions with’
aqueous or gaseous hydrochloric acid and ether.
The present paper is an account of procedure for the pre-
cipitation of barium chloride from water solution and its sepa-
ration from calcium and magnesium by the use of acetyl chloride
to decompose the water of the solution according to the reac-
tion CH,COCl + H,O = CH,COOH + HCl, inconvenient vio-
lence of reaction being moderated by the addition of acetone
which mixes in all pr oportions with both acetyl chloride and
water and by itself exerts no appreciable solvent action upon
barium chloride.
When a mixture of acetone and acetyl chloride, preferably
4:1, is added slowly to a very concentrated solution of barium
chloride in water, the water is attacked at once, hydrogen
chloride is liber ated, and precipitation begins immediately. Gi
the temperature is kepi down during the process by immers-
ing in cool running water the vessel in which reaction takes
place, no more than a mere trace of barium can be detected by
sulphuric acid in the residue left after evaporating the liquid
separated from the precipitate by filtration through asbestos.
When, however, the temperature is allowed to rise, in conse-
quence of the heat liberated in the reaction, an appreciable
amount of barium may be found by sulphuric acid in the
filtrate. Below are given the data of experiments in which
the residue obtained (a) by treating a solution of barium
chloride in 1 of water with 30°? of a 4:1 acetone- -acety|
chloride mixture and collecting the precipitate upon asbestos
in a perforated crucible, washing with acetone and with ether,
was weighed after drying in air, then (0) treated on the asbes-
tos for ten minutes with 15-20 of acetyl chloride, washed
with acetone and with ether, dried in the air and weighed,
then (¢) digested for ten minutes with 20-25°* of 2:1 ace-
tone-acetyl chloride mixture, washed with acetone and with
ether, dried in the air and weighed, and then (d@) heated in the
air-bath, or to low redness, and weighed.
* Mar, this Journal [8], xliii, 521; Havens, this Journal [4], ii, 416; iv,
111; vi, 45; vi, 396.
Associated with Calcium and Magnesium. 213
Experiment I PLE ae II
—_——_-+7~ ——
Weight Loss Weight Loss
grm. grm. grm. grm.
BaC],.2H,0O taken ..-- -_-- OghOM 2M ee OULOOO a eee
(a) Residue after precipitation,
washing, and drying in air, 071008 0:0004 0:0996 0:0004
(b) Residue after treatment with
acetyl chloride, washing,
andl dyamereim a, 2-1 071006 0:0002 90:0996 0:0000
(c) Residue after treatment with
acetone-acetyl chloride mix-
ture, washing, and drying
Maas SO las 0:0985 0:0021 0°0981 0-0015
(d) Residue after heating, BaCl, 0:0846* .... 00839 © .---
BaCl,.2H,O corresponding to
ba@ le Townde easy: = sans OOO 35) oe Ser COLO9SD ein. cae.
‘Loss of BaCl,.2H,O due to
solubility and dehydration ---. 00027 ---.- 0°0019
Loss of BaCl,.2H,O due to
solubility, calculated from
BaCl,.2H,O taken and BaCl,
OUMKC ee a tes eee eee TS ES ff OLOOLINE |. era =z 0'0015
Wosspby, dehivdiratione jae =)t ae. 010008) "2-3-1" 020004
* Heated to low redness. + Heated to 135° for 114 hrs.
From these results it appears (a) that when the acetone-
acetyl chloride mixture (4:1) acts upon the cooled concen-
trated water solution of barium chloride the precipitate is the
hydrous chloride, BaCl,.2H,O, only the water in excess of that
needed to form the hy drous salt being immediately attacked ;
(6) that acetyl chloride by itself pr oduces only slight dehydra-
tion of the salt without marked solubility ; and ‘(e) that pro-
longed action of the acetone-acetyl chloride mixture (2:1)
results in appreciable dehydration and considerably increased
solubility of the salt. By fnrther experimentation it was
shown that when the acetone-acetyl chloride mixture is added
without cooling to the water solution of barium chloride the
heat of reaction favors dehydration of the hydrous salt, and
the anhydrous salt may go into solution to the amount of
several milligrams in 10° of the precipitating mixture. Upon
filtering the mixture and treating the filtrate with acetone,
with acetyl chloride, or with the acetone-acetyl chloride mix-
ture the dissolved anhydrous salt is not thrown out of solution,
214 Gooch and Boynton— Estimation of Barium
but the addition of a drop of water is sufficient to induce
immediate precipitation in the form of the hydrous salt.
Incidentally it is interesting to note that when water acts
upon the colorless mixture of acetone and acetyl chloride the
solution becomes yellow, and then reddish, and develops a
distinetly fruity odor, condensation taking place between the
acetone and acetyl chloride. The boiling points of the col-
lected filtrates from a series of barium chloride precipitations
after standing about a week ranged from 50:5° to 250°, and
left a resinous residue at that temperature.
From the results of the experiments described, it may be
inferred that the best conditions for the quantitative precipita-
tion of barium chloride by the acetone-acetyl chloride mixture
should be found in the use of minimum amounts of water, the
preservation of ordinarily low temperature, a liberal propor-
tion of acetone, and not too prolonged digestion of the precipi-
tate in the excess of the precipitant. These conditions have
been complied with in the quantitative tests.
Barium chloride was prepared for the work by precipitating
it with strong hydrochloric acid from a water solution of the
presumably pure salt, recrystallizing twice from water, and
drying in the air. On gentle ignition the salt lost water cor-
responding to the ideal composition of the hydrous chloride,
- BaCl,.2H,O. In each test a portion of this salt was weighed
out into a small beaker and dissolved in 1°™° of water. The
beaker was cooled by immersion in a water-bath preferably
supplied with running water at a temperature of about 15°.
To the cooled solution, constantly shaken, the acetone-acety]
chloride mixture was added from a dropping funnel at the
rate of five drops to the second. Other data of the experi-
ments with barium chloride are given in Table I. The pre-
cipitate was filtered off upon asbestos in a perforated crucible,
dried, or ignited, and weighed as the anhydrous chloride, BaCl.,,.
From these results it appears that the best of the conditions
studied for the handling of 0-1 grm. of hydrous barium chlo-
ride are the solution of the salt in 1°° of water, treatment
with 30° of the 4:1 mixture of acetone and acetyl chloride,
washing with acetone, and drying in the air-bath at 135° or
at low redness.
' The application of these conditions to the separation of
barium from moderate amounts of calcium and magnesium
proves to be easily feasible. When acetone is added to the
concentrated solution of calcium chloride or magnesium chlo-
ride in water two liquid layers are formed, the acetone above
and the aqueous layer below; but the addition of a few drops
of acetyl chloride renders the liquids miscible while further
addition causes no precipitation. When the 4:1 mixture of
Associated with Calcium and Magnesium. 215
TABLE J.
The Estimation of Barium.
Amount of mixture and
BaCly Water to composition by volume
taken as BaCl, dissolve ———_—_—— tH
BaCl,.2H,0 found Error BaCl,.2H.O To precipitate To wash
grm. grm. grm.
1-0°0859 0:0859 —0-0000t ems Get eal OGL
2-0:0861 0:0854 —0-0007t ES RE Oe TOE
3-0°0861 0°0858 —0:0003f ss aE oil HOSP et
4-0°0862 0:°0854 —0-0008* ee Ge! Weil LOPE Bei
5-0°0857 0:0854 —0-0003* sf ecm? 931 UIE Weil
6-0°0858 0:0860 +0:°0002* ve (HOE BT, i Oto abe
7-0°0860 0:0859 —0-:0001* © § Ge! Beil SO Za
8-0°0853 0°0850 —0:0003* WY Ger acetone
9-0°0854 0:0848 —0:0006* fs Gone 2 il y
10-0°0852 0°0851 —0-:0001* “s 6cem® 221 ss
11-0°0857 0:°0856 —0-0001t oo Ge Beil a
12-0:0852 0°0845 —0-0007+ os Goat) Beil ce
13-0°0855 0°0852 —0-0003+ oe Gore o a Hy
14-0°0862 0:0862 —0-0000t He SOc es
15-0°0868 0:0868 —0-0000t ee BOY Zep ss
* Ignited at low redness. + Dried at 185° for 144 hrs.
acetone and acetyl chloride is added at the rate of five drops
in the second to the solution containing no more than 0°5 grm.
of the calcium and magnesium salts, barium chloride is pre-
cipitated and calcium chloride aud magnesium chloride are
dissolved ; but when the soluble chloride is present in the pro-
portion of 1-0 erm. to 0'1 grm. of the barium chloride, the
rate of addition of the precipitating mixture should not be
greater than two drops in the second at the start in order to
avoid inclusion of the soluble salt in the insoluble barium salt.
Even in such cases the mixture may be added at the rate of
tive drops in the second, after the greater part of the barium
is down. Tables II and III contain the data of experiments
upon the separation of barium from calcium and magnesium.
The results obtained in the separation of 0-1 grm. of the
barium salt from 0°5 grin. of calcium and magnesium salts are
excellent.
The separation of barium from strontium proves not to be so
simple. When the 4:1 mixture of acetone and acetyl chloride
is added to the concentrated water solution of 0-1 grm. of
strontium chloride a partial precipitation takes place. When
the precipitate thus produced was filtered: off, washed with ace-
tone and with ether, and dried in air, it lost SET amounting
to 19°93 per cent and 20-00 per cent of its weight on heating
216 Gooch and Boynton—LKstimation of Bariwm
TABLE II,
The Separation of Barium from Calcium.
» Ba), Water used Amount of
takenas CaCl,.2H.O BaCl, to dissolve mixture
BaCly.2H;0 taken found Error salts (4:1) used
grm. erm. grm grm. em?, em?,
1-0-0859 01000 0:0859 0°0000* hs ae 30
2—0:0867 071040 0°0867 0:0000* 1 S30)
3—0°0868 0°1022 0:0868 0:0000* il 30
4-0:°0865 0°1020 00865 0°0000* 1 30
5-0°'0868 01017 0°0869 +0:0001* 1 30
6—0°0864 071016 0:0861 —0:0003* 1 30
7—-0°0866° 0°3025 0°0867 +0:0001*. 14 30
8—0:0859 075025 0:0859 0:0000* 2 30
9-0°0860 1:0020 0:0878 +0:0018* 3 30
10—0°0859 10020 0:0855 — 00004 2 30
11-0°0864 1°00385 0:0867 + 0°0003F 2 30
* The precipitant was added at first at the rate of five drops in the second.
+ The precipitant was added at the rate of two drops in the second at the
outset and later of five drops in the second.
TaBLeE Lil.
The Separation of Barium from Magnesium.
BaCl, Water used Amount of
taken as MgCl..6H.0 BaCl, to dissolve mixture
BaCl..2H.,0 taken found Error salts (4:1) used
grm. germ. grm. germ, cm’. em’,
1—0°0858 071000 0°0857 —0-:0001* u 30
2—0°0869 0'1025 0:0870 + 0°0001* i 30
3-0°0858 0°1025 0°0858 0:0000* 1 30
4—0°0862 0°1010 0:08638 =+0°0001* h 30
5-0'0858 071006 ~=—- 00860 +0:0002* 1 30
6—0'0860 0°1020 0°0859 —(:0001* i 30
7—0:0860 0'1010 = 0:0862 “+ 0:0002* 1 30
8—0'0865 0°3010 0°0867 +0°0002* 14 30
9-0°0864 0°5000 =0°0867 +0:0003* 2 30
10—0°0868 1:0015 = 0°0878 +0°0010* 3 30
11-—0°0853 10010 0:0854 . +0:0001t 3 30
* The precipitant was added at the rate of five drops in the second,
+The precipitant was added at first at the rate of two drops in the second
and later of five drops in the second.
to 185°. Obviously the salt was essentially SrCl,.2H,O, which
should contain theoretically 18°51 per cent of water. This
precipitate of SrCl,.2H,O when treated with a mixture of ace-
tone and acetyl chloride containing a larger proportion of the
latter, goes into solution and is again partially precipitated upon
increasing the proportion of «cetone, essentially as SrCl,.2H,O.
Associated with Caleium and Magnesium. 217
When a mixture richer in acetyl chloride, the 2:1 mixture of
acetone-acetyl chloride, is added to the concentrated water solu-
tion of strontium chloride, the precipitate first formed is slowly
redissolved in a sufficient excess of the mixture and again
partially precipitated upon the addition of more acetone. This
second precipitate of SrCl,.2H,O is not completely soluble,
however, when the proportion of acetyl chloride is again
increased, but will dissolve upon the addition of an acetone-
acetyl chloride mixture to which a few drops of water have
been previously added and which is, therefore, charged with
hydrogen chloride. So it appears that the solubility of the
strontium chloride, SrCl,.2H,O, depends to a very large extent
upon the concentration of hydrogen chloride in the mixture.
In attempting the separation of barium from strontium,
therefore, it was the 2:1 mixture of acetone with acetyl choride
which, on account of its higher power as a solvent for
SrCl,.2H,O, was added to the concentrated water solution of
* the barium chloride and strontium chloride, though this mix-
ture has been shown to be somewhat less favorable to the com-
plete precipitation of barium chloride than the (4:1) mixture
containing the larger proportion of acetone, and the addition
was made at the rate not greater than two drops in the second
or 30 in ten minutes. ‘The precipitate, filtered upon asbestos
and washed with acetone, was dried at 135°. The data of
these experiments are recorded in the table.
The separation of barium from strontium by the process
TABLE IV.
The Separation of Barium from Strontium.
BaCl, Water used Amount of
taken as SrCl, BaCl. to dissolve mixture
BaCl,.2H,0 taken found Error salt (2:1) used
grm. grm. grm. grm. em?, em?,
1-0°0867 0°0385 0:0923 + 0°0056 1 30
2—0'0866 0°0304 0°0857 —0°0009 1 30
3—0:0860 0°0320 0°0861 +0°0001 1 30
4—0°0856 0:0315 00840 —0°0016 1 30
5—0°0856 0°0307 0°'0848 — 0°0008 1 30
6-0'0859 0°0304 0:0839 —0°0020 ] 30
7—0:0862 0:0307 0:0859 —0°0003 1 30
8—0°0857 0:03815 0'1160 + 0:0303 0°5 30
9-0°0857 0:0317 01058 +0:0201 0°5 30
10-0°0853 0°0315 0'1083 + 0°0230 0°5 30
11-0:'0869 0°6305 0'1043 +0°0174 0°5 30
12—0°0863 0°0307 0:0906 + 0:0043 0°5 30
13—0°0859 0'0808 0:0849 —0:0010 0°5 30
14-0:°0869 0°0108 0:0870 +0:0001 1 30
15—0°0865 0°0110 0°0858 —0:0007 1 30
16—0°0853 0°0115 0°08538 + 0°0000 1 30
17-0:0861 0:0109 0:0870 + 0:0009 1 30
218 Gooch and Boynton—Estimation of Barium.
described is obviously only approximate, some barium chloride
going into solution in the 2:1 mixture of acetone and acetyl
chloride, while the solubility of the strontium chloride turns
upon the amount of water originally present—that is, upon the
development of hydrogen chloride:
It appears, therefore, that the method which rests upon the
action of a 4:1 mixture of acetone and acetyl chloride upon the
concentrated solution of the chlorides affords easy and exact
means for the separation and estimation of barium associated
with calcium and magnesium. It is not recommended for the
separation of barium from strontium. :
— ee = =
Arr. XXI.—A Feldspar Aggregate Occurring in Nelson
Co., Virginia; by Witt1am M. Tuornton, Jr.
Near Rose’s Mill in Nelson Co., Virginia, the General -
Electric Company recently carried on some mining operations
with the view of obtaining rutile, where it occurs as a rock-
forming mineral in the unique rock type ‘‘nelsonite.”* To give
some idea of the nature of this peculiar rock, an analysis of the
rutile phase is here inserted :
Analysis of Nelsonite.—General Electric Company’s mine?
14 miles northwest of Rose’s Mill. Essential minerals :—Rutile
(TiO,) and apatite (Ca,FP,O,,). Accessory minerals :—Ilmen-
ite (FeTiO,), pyrite (FeS,), and yuartz (Si0,).
SION SOLER ene ho feta bene eee 0°67 per cent
Bei O) rae SR NGhe oe wets serene tae EOI ee
HeOr.=_ a es wie aD ee lke La ee aes ema) () fy ss
MeO re aye oo 2 eae ae eee eae OmlaeD es
CaO See ee eee eee He “
HO! (ab 110° Cpe ee ae Oe
EVOy(above 110 21@:) Gee sens ae 0-1] a
DiO ie eo), aie ge 6967“
Pe io be Oe au L Seed eee ote RON ee Aa ee
(Cleese Ben ies ate Ss ENS :
AE eimai age em (10) Fe
SS eee ie Ur Se ne Ree eee 0°34 ce
101°21
Dp (orejfsy OM ae veered Hayy 8 0°39
SUD EMIT AO 11 —— an ye 100°82
At this place the narrow, well-defined dike of nelsonite
intersects a metamorphosed pegmatite. The pegmatite is
*Name proposed by T. L. Watson, Director Virginia Geological Survey.
Seve Mineral Resources of Virginia, 1907, p. 300.
W. MW. Thornton, Jr—A Feldspar Aggregate. 219
composed essentially of feldspar and blue quartz and in places
much hornblende. The accessory minerals ilmenite and pyrite
and apatite are also present. The feldspar is by far the domi-
nant portion of the rock; and, since it presents some unusual
features, it was thought by the author that a study of its com-
position would prove of some interest. Of course the natural
procedure would be to isolate mechanically the feldspathic por-
tion and to analyze the most homogeneous material obtainable.
But three analyses of the pegmatite were required for geolog-
ical purposes; and since time was lacking in which to make a
fourth of the feldspar alone, it was decided to employ the
analysis of the extreme acidic phase for calculating the compo-
sition of the feldspar.
The color of the feldspar is light bluish gray. Under a
magnifier of twenty diameters it appears decidedly transparent
and glassy. The texture is one of very close crystalline
aggregation. Specific gravity = 2°68. From all outward
appearances one would suppose it to be a definite species; but
the analysis and portioning of the molecules to form the respec-
tive feldspars in the accompanying table shows it to be a
mixture of orthoclase and plagioclase, and that the plagioclase
is made up of albite and anorthite in the ratio of 10 to 7.
This is also confirmed by microscopic examination of thin
sections. *
Pegmatite (feldspathic facies) near Rose’s Mill, Nelson Co., Virginia.
Per Mo. Rel. no.
cent wt. mos. Rel. no. feldspar mos.
SLO Smee se ean ae ae 59°92 = 60 = 0:9987 2K AISi;0, = 0°08117
Als Oy eee Sea ee a eal 24°23 +102 = 0°2375 2NaAl1Sis0, = 0:081
Hie) © seeks Sytner aa 0:29 CaAl.Si,0, = +1137
LSE Os SR Da ee aN 0°24 [CasP20,; = -0006]
Mie Oia cee a IS Soars as 0:23
Cia Os Sra eh ais as ek 6°47 = 56= 01155 .-. NaAISi;0; : CaAl.Si.0, =
Nias OE ee ae a le Fe 5°03 + 62 = 0:081 Ql == LON 7
NEG Os Sa TS eS Ne a 2°93 + 94 = 0:03117
HeOlat T07C:) 222255 0-08
H.O (above 110° C.)_.-_- 0°28
(CLO) Sts ae lars eee mee trace
AUTO Pps Gee eR Sis aeetee ea ae 0:22
To O) plete ie ye leet eos 0-09 +142 = 0:0006
SC eee Pees Me eo trace
IVErn Ocha ely apn see Re trace
100°01
Pegmatite: = .*. orthoclase — 17°337 per cent, plagioclase (Ab;,An;)
74:057 per cent.
Composition of feldspar, aggregate : orthoclase 18°96 per cent ; plagioclase
(Ab,.An7) 81:04 per cent = 100°00.
* Bull. 430-D, U. S. Geological Survey, p. 57. ‘‘The Virginia Rutile
Deposits,” by T. L. Watson and S. Taber.
220 =W. M. Thornton, Jr.—A Feldspar Aggregate.
After combining all the potash molecules with alumina and
silica to form orthoclase and likewise all the soda molecules to
form albite and all the lime molecules (except enough to satisfy
the phosphoric anhydride to form apatite) to form anorthite,
there is a little alumina in excess. This can be accounted for
by assuming the hornblende to contain some alumina, which
is probably the case, or by errors in the determinations.
In general the methods of analysis employed were those in
use by chemists of the U. S. Geological Survey. In the
determination of the alkalis the purest reagents of Dr. T.
Schuchardt were used, and the filtrate from the first lime
precipitation was concentrated in a silver basin; glass and
porcelain vessels were avoided where any error might arise
from their use.
Virginia Geological Survey,
University of Virginia, January 16, 1911.
O. F. Cook—History of the Coconut Palm in America. 221
Arr. XXII.—Wistory of the Coconut Palm in America ; by
O. F. Coox.*
Many scientific text-books and works of reference support
the popular idea that the coconut palm is specially adapted to
tropical seacoasts and is confined to maritime regions. No
other example of special adaptations of plants to their environ-
ments has had longer currency or more confident belief.
Nevertheless, it seems that the botanical romance of the coco-
nut, protected by its thick husk and floated from island to
island in advance of human habitation, must go the way of
many other pleasing traditions. What natural agencies have
been supposed to do for the coconut is now to be recognized
as the work of primitive man. The truth proves again to be
stranger than the fiction.
The coconut exists in the lowland tropics only as a product
of cultivation. It does not plant or maintain or distribute
itself on tropical seacoasts, and would entirely disappear from
maritime localities if human care were withdrawn. The
habits of the palm from the botanical standpoint, its signifi-
cance in human history, and even its agricultural possibilities
are misunderstood unless we are able to lay aside the maritime
traditions.
An outline of the evidence for the American origin of the
coconut palm and of its distribution by human agencies has
been published in a previous number of the Contributions.+
The present study carries the subject further in two principal
directions. It brings additional facts to show that the coco-
nut palm was already widely distributed in the New World
before the arrival of the Europeans, and that it is not naturally
a maritime or humid tropical species, but a native of drier and
more temperate platean regions in South America. A com-
parison of the habits of germination of the coconut with those
of other related American palms shows other and very differ-
ent uses for the characters that have been looked upon as
special adaptations for maritime dissemination.
The huge seed with its immense store of food materials and
its thick fibrous husk make it possible for the coconut to
propagate itself im the relatively dry interior localities where
it appears to have originated. The inability of the palm to
withstand shade explains why it has been unable to establish
* Extracted from Contributions from the U. S. National Herbarium, vol.
xiv, pt. 2, pp. 271-342, 1910. The portions here given are from the intro-
duction and summary.
+ The Origin and Distribution of the Cocoa Palm, Cont. Nat. Herb., vol. vii,
pp. 257-298, (1901.)
Am. Jour. Sci.—FourtH SERIES, Vor. XX XI, No. 183.—Marcga, 1911.
16
222 O. F. Cook— History of the Coconut Palm in America.
itself as a wild plant on any tropical seacoast. The application
of these facts to cultural problems shows that the possibilities
of an extratropical extension of the coconut palm are not to be
realized on seacoasts, but in interior desert regions where
larger amounts of heat and sunlight are to be obtained.
Though the biological evidence of the American origin of
the coconut palm appears complete and adequate, recent years
have brought to light several additional facts which may be of
use to those whose training and habits of thought lead them to
attach great weight to the historical arguments of De Candolle
and other writers who believed in the Old World origin of
this palm and its dissemination by the sea. The reader is
impressed by De Candolle’s references to many old and rare
books, and will naturally remain loth to believe that so eminent
an authority could have come to an erroneous conclusion,
unless all the foundations of his opinions are carefully reex-
amined.
It is important to trace and clear away any mistakes or false
deductions which obscure the early history of cultivated plants.
Misconceptions regarding the origin and dissemination of any
important economic species tend to distort human history as
well as to mislead botanical and agricultural investigation. It
is only when we view the past with the right perspective that
we gain correct ideas of the factors which control our present
interests and our future progress. Civilization itself is based
on cultivated plants, and history may be written with as much
propriety from the agricultural standpoint as from the mili-
tary, political, or commercial.
SuMMARY OF RESULTS.
The history of the coconut palm has relation to several
different kinds of scientific questions, so that the facts require
to be summarized from several different standpoints.
Botanical Conclusions.
All the palms that are related to the coconut, comprising
about 20 genera and 200 species, are natives of America, with
the possible exception of a single species, the West African oil
palm. All the species of the genus Cocos and of the closely
allied genera are natives of South America. The species of
Cocos that are most related to the coconut are natives of the
interior valleys and plateaus of the Andes, where the coconut
also thrives, remote from the sea.
Comparison of the structure of the fruit and the method of
germination of the coconut with those of the related palms
indicates a high degree of specialization, but not for purposes
of maritime distribution. The unusually large, heavy seed and
O. F. Cook—LHistory of the Coconut Palm in America. 223
the thick, fibrous husk are to be considered as adaptations for
protecting the embryo, assisting in germination, and establish-
ing the young plants in the dry climates of interior localities,
the only conditions where this palm could be expected to
maintain its existence in a wild state.
The habits of the coconut palm afford no indication that its
original habitat was on the seacoast, and none of its closer
relatives have maritime habits or maritime distribution. The
coconut palm does not appear to be able to maintain itself
under littoral conditions without the assistance of man. Though
carried by man to all of the warmer parts of the earth, it has
not been able to establish itself as a wild plant on any tropical
coast, but. is always crowded out by other vegetation after
human care is withdrawn.
Wafer’s circumstantial account of the existence of large
numbers of coconut palms on the Cocos Islands, 300 miles
west of Panama, in 1685, taken together with their almost
complete disappearance at the present day, affords a striking
illustration of the dependence of the coconut upon human
assistance, not only for distribution, but for its continued exist-
ence on oceanic islands.
The dissemination of the coco palm along the tropical coasts
is to be ascribed to the agency of primitive man, as with the
sweet potato, banana, and other domesticated plants which
were widely distributed in prehistoric times. The theory that
it has been disseminated by ocean currents is gratuitous,
unproved, and improbable.
The development of distinct varieties of the coconut has not
been confined to the Polynesian and Malayan islands. Dis-
tinct varieties are also to be found in isolated localities in
America, such as the Soconusco region of Mexico and the
island of Porto Rico.
The existence of many and diverse varieties in the Malay
region does not indicate that the species is native there, but the
opposite, since the proximity of the wild stock of a species is
likely to hinder the appearance and preservation of mutations
among its cultivated representatives. The relative uniformity
of the coconuts of America is in accord with the probability of
an origin in this hemisphere. The discovery of distinct varie-
ties in isolated localities in America accords with the proba-
bility that the Malayan varieties have arisen, like other culti-
vated varieties, through segregation and mutation rather than
by gradual evolution and natural selection.
Historical Conclusions.
At the time of the discovery of America the coconut was
not confined to the Pacific side of the Isthmus of Panama, as
224 O. F. Cook—Tistory of the Coconut Palm in America.
De Candolle believed, but was already widely distributed along
the Atlantic side of the American tropics. Early records show
its presence in Cuba, Porto Rico, Brazil, and Colombia at dates
so early as to preclude the idea of introduction by the Spaniards,
The statement of Pickering, frequently quoted in works of
reference, to the effect that coconuts were reported by Columbus
on the coast of Central America during his fourth voyage,
proves to be erroneous. On the other hand, there appears to
be a definite reference to the coconut in Cuba in the journal
of the first voyage of Columbus.
De Candolle’s inference from Acosta’s report of coconuts in
Porto Rico at the end of the sixteenth century, that they had
recently been introduced by the Spaniards, proves to have no
warrant in history and is directly opposed by the more extended
reference to the coconut in Porto Rico by the Duke of Cum-
berland’s chaplain, who visited the island only a few years after
Acosta.
De Candoile’s use of the testimony of Piso and Marcerave
to support the idea of the introduction of the coconut into
Brazil by Europeans is also unwarranted, since those writers
only indicated that the plant was cultivated. An earlier and
more explicit record, unknown to De Candolle, gives an
account of the coconut as one of the native products of Brazil.
The journal of Cieza de Leon, who accompanied the first
Spanish expedition to the interior of Colombia, indicates the
presence of the coconut palm in localities where it still con-
tinues to exist, as shown by the accounts of Velasco, Humboldt,
and more recent travelers, down to the present decade.
Ethnological Conclusions.
The American origin of the coconut palm and the strict
limitation of its status in maritime tropics to that of a culti-
vated plant are facts of ethnological significance. The wide
distribution of the coconut in prehistoric times is evidence of
the antiquity of agriculture in America and of very early
communication across the Pacific.
The American origin of the coconut palm, along with its
inability to maintain itself on tropical seacoasts without human
assistance, compels us to believe that its trans-Pacific distribu-
tion was the work of primitive man. The dependency of the
Pacific islanders upon the coconut may be taken to show that
these islands could not have been occupied without the pre-
vious domestication and dissemination of the coconut.
In view of the fact that several other palms of unquestioned
American origin have been domesticated by aborigines of the
American tropics, no ethnological objection can be raised to
O. F. Cook—History of the Coconut Palm in America. 225
the idea that the coconut palm was originally domesticated in
ancient America.
The name “coco” does not appear to have been applied to
the “Indian nut” till after the discovery of America and is to
be considered as a word derived from the natives of the West
Indies. Other native names for the coconut are found among
primitive tribes of Costa Rica, as well as in Brazil.
The presence of large numbers of coconuts on Cocos Island
in the time of Wafer (1685) and their subsequent disappearance
should be considered as evidence that the island was formerly
inhabited, or at least regularly visited, by the maritime natives
of the adjacent mainland.
The fact that the coconut is largely restricted to islands and
tropical countries of low elevation explains its importance
among the preéminently maritime people of the Old World
tropics and its relatively slight importance among the nonmari-
time natives of the lowland tropics of America.
The evidence of the prehistoric dissemination of the coconut
and other American cultivated plants across the Pacific Ocean
is such as to warrant a careful consideration of other indica-
tions that agricultural civilization developed originally in
America and was distributed to the shores of the Pacitie and
Indian oceans by a primitive people with agricultural and
maritime habits, like those of the Polynesians and Malays.
The existence of a distinct tribe of frizzle-haired people near
the Isthmus of Panama at the time of the discovery does not
rest alone on Peter Martyr’s casual mention of the finding of
negroes, but is supported by Oviedo’s contemporary history
written directly from the testimony of Balboa and other mem-
bers of his expedition, just after their return to Darien. The
facts are not to be explained reasonably by assuming a chance
arrival of African negroes, but indicate that prehistoric com-
munication across the Pacific continued after the frizzle-haired
Melanesian race had spread westward in the Pacitic.
Such communication would account for the existence of the
banana plant in America previous to the arrival of the Span-
jards, as well as for the Old World distribution of the coconut
palm and other cultivated plants of American origin. The
banana plant is as evidently a native of the eastern continent
as the coconut palm of the western. Evidence of these facts
appears very definite and concrete from the biological stand-
point, and is worthy of careful consideration by ethnologists.
Agricultural Conclusions.
The coconut is confined to seacoasts only in the humid low-
lands of the Tropics; in dry regions it is not restricted to
coasts, but thrives in many districts remote from the sea. The
226 O. F. Cook—History of the Coconut Palm in America.
fact that it received scientific study only as a maritime plant
should not longer obscure the fact that it is also adapted to
interior localities with saline soils. The cultural problems of
the coconut palm should be investigated quite apart from the
idea of maritime habits and distribution.
The possibility of raising coconuts in frost-free localities out-
side the Tropics is not to be tested along the seacoast, but in
interior districts where larger amounts of sunlight and heat are
available, as in the valleys of southern California and Arizona.
The coconut, like many other plants, is not tolerant of shade
nor of long-continued cool and cloudy weather. Other species
of Cocos that are less exacting in their requirements of sun-
light and heat have been found to do well along the California
coast.
The possibility of introducing coconut palms into southern
California is not disproved by the absence of these palms from
Egypt and Palestine. Though the climatic conditions are
probably favorable, it does not appear that any adequate effort
has been made to introduce the palms in those countries.
The ability of the coconut to thrive on seacoasts shows that
its requirements of heat are not as great as those of the date
palm. Though probably less hardy than the date palm, it is
not impossible that the coconut may be able to exist in frost-
free localities that have not enough heat for the ripening of
dates.
The possibility of introducing the coconut palm into southern
California and Arizona can not be fairly tested by the planting
of the maritime varieties. The chances of success will be very
much greater with the varieties that are adapted to the dry
interior localities of the temperate plateaus of the Andes.
Loomis—New Mink from the Shelt Heaps of Maine. 227
Arr. XXTIL—A New Mink from the Shell Heaps of Maine ;
by F. B. Loomis.
Dorine the summer of 1909 the Amherst Biological Expe-
dition collecting in the shell heaps along the Maine coast,
opened the heap on the east side of Flagg Island in Casco Bay,
near South Harpswell. This heap is distinct from any of the
others in several features, but especially in having large num-
bers of mink bones in it, the mink being, however, larger than
any species now living in New England and markedly different
from any that are known. It is as large as the largest species
from Alaska.* In the course of the week spent in the Flage
Island heap no less than 45 individuals were found in which
there were 10 upper and 34 lower jaws of males, and 2 upper
and 11 lower jaws of females. Beside these 3 lower jaws
of the same species were found in the heap on Sawyers Island
near Boothbay, 2 in the Seward Island heap in Frenchman’s
bay, and one in the Winter Harbor heap. The other localities
worked did not offer any of this mink; so that it would appear
that Flagg Island was more or less overrun with these minks
during the shell heap period, while they occurred also in small
numbers along the coast to the east and north.
The exact time when they lived is difficult to estimate, but
the heaps contain nothing of European origin, so they were
accumulated before 1627 and are probably as much older as it
took to build them up, perhaps 200 to 400 years more. The
mink is not confined to any one level on Flage Island but
occurred all through the heap; so that it is to be thought of as
having lived on the Maine coast for some hundreds of years.
None of the skeletons were found associated, nor were any
of the skulls perfect. In every case the mink had served as
food for the aboriginal campers, so that the carcass had been
pulled to pieces and the bones thrown away in various direc-
tions. Every skull has the brain case broken and lost, the
brain having apparently been used for food. The facial por-
tion of each skull is, however, pretty much intact, indicating
that the meat was simply picked off it. Many of the lower
jaws are marked with tool scratches (see fig. 2) apparently
made while removing the meat from the bones.
This form is much larger than any of the living New
England species, being all of 25 per cent larger than Lutreola
(weson) lutreocephalus* Harlan, the large brown mink, and
*N. American Fauna, Dept. Agriculture, No. 19, 1900, p. 42.
+ Bangs, North American Minks, Boston Soc. Nat. Hist., Proceedings,
vol. xxvii, 1897, p. 1-6. ‘
228 Loomis—New Mink from the Shell Heaps of Maine.
equal in size to the Alaskan Z. vison ingens Osgood. This
new form may be described as follows:
Fie. 1.
Fic. 1. A, the upper dental series of the type specimen, nat. size. B, the
skull seen from above, nat. size.
Lutreola vison antiquus sp. nov.
The type is a male skull lacking the brain case together
with an associated right lower jaw, numbered M 1401 in the
Fie. 2.
Fie. 2. 6 lower jaw, nat. size; a is scratch made by aboriginal tool in
removing the flesh. ¢? lower jaw of female, showing relative size.
Amherst Collections: and also a right lower jaw of a female
numbered M 1402, both from Flage Island shell heap.
Loomis — New Mink from the Shell Heaps of Maine. 229
The form is large and heavily built, the skull with a low
sagittal crest and short wide postorbital processes. The frontal
region is slightly arched between the orbits. The teeth are
those typical of the genus but rather stouter and heavier than
usual. The inner tubercle of the upper carnassial is single and
rather small.
With this larger and typical form occur numerous individuals
about 20 per cent smaller, but otherwise with the same char-
acteristics, which I take to be the females, as there is in the
family usually about this difference in size between the sexes.
The following measurements give the data for comparisons:
CG uppermental’ series). 22. 8222 2 es 99) 1 /2mm
fe) T3 75 Oi A na he eR LE Warts ee SON Bs 95mm
& lower dental series...-._-..--...-. -. 30™™
Q “ “cc CA Awe ao ene Oe mmM
eG uuppen Catnassiple:t of paar tek es 8 1/47™
fe) “e ce ey gcie swe MUTE AS RIOR aS eR aey ee! 7 3/4m™
2 width between the orbits.._.____._-- _ 20mm
For other measurements see figures, which are drawn to
scale.
‘Amherst, Mass.
230 Scientific Intelligence.
SCIENTIFIC INTELLIGENCE,
I. Cnemisrry Ann Purysics.
1. Mesothoriwn.—The existence of this radio-active element as
one of the products of thorium was established in 1907 by Hahn,
who showed that its half decomposition period was about 54
years, and that it was separated from thorium in the commercial
extraction of the latter from its ores. Later, Hahn was able to
find this substance in the residues from the extraction just men-
tioned, and he showed that it is not directly transformed into
radiothorium, but that there is an intermediate product with a
half-period of 6-9 hours, which he called mesothorium II. Hahn
has recently been able to concentrate this last substance to such
an extent that the radio-activity of the product is several times
greater than that of pure radium salts.
W. Marcxwatp bas now made some interesting observations
in regard to these substances, for it appears that nothing has been
published concerning the chemical properties of mesothorium I.
He had occasion to examine a “radium preparation” which had
been manufactured from the residues of uranium and thorium
ores. This preparation, consisting chiefly of barium chloride,
gave a y-ray radiation corresponding to more than 1 per cent of
radium chloride, but the radium emanation obtained from it
corresponded to only about 0°2 per cent of radium. A further
study of the product showed that about 80 per cent of the y-radi-
ation came from mesothorium II, for when an aqueous solution of
the salt was treated with a trace of ferric chloride and made
ammoniacal the mesothorium II was precipitated with the ferric
hydroxide. The precipitate gave a strong y-radiation, while the
barium chloride recovered from the filtrate by evaporation had
lost almost the whole of this radiation. However, while the pre-
cipitate lost its activity at the rate of one-half in about 6 hours,
the salt regained the greater part of its activity within a day.
The precipitate by ammonia must have contained also the
radiothorium produced by the mesothorium, and in fact this was
found to be the case, as the precipitate gave the a-rays of the
thorium emanation after the disappearance of the mesothorium II.
Mesothorium is evidently entirely analogous to radium in its
chemical behavior, for Marckwald has been unable to find any
means of separating the two. This is interesting in connection
with the fact that no chemical method is known for separating
the four elements, thorium, radiothorium, ionium and uranium X,
and it appears that radium and mesothorium form a similar group,
which possibly may contain other members also. It is evident
that radium preparations are liable to be contaminated with meso-
thorium, and since radium has a period of existence about 300
times as long as the other, this contamination is of much import-
Chemistry and Physies. 231
ance. There is a possibility, not only of accidental contamina-
tion, but of wilful adulteration. The best means for testing
radium preparations for mesothorium is to remove the radium
emanation either by heating or by solution and evaporation ;
then the presence of y-rays after a few hours shows the presence
of mesothorium. The proportion of y-rays before and after this
treatment gives an indication of the amounts of the two radio-
active substances present. — Berichte, xliii, 3420. H. L. W.
2. The Combustion of Hydrocarbons.—In a recent lecture
before the British Association, W. A. Bonz has given a review
of the present knowledge of gaseous combustion, much of which
is due to his own important researches. The opinion which
formerly prevailed among chemists that in combustion the hydro-
gen of hydrocarbons is first attacked by oxygen with the forma-
tion of steam is incorrect. It has been known for a long time
that when ethylene and acetylene are exploded with equal vol-
umes of oxygen, carbon monoxide and hydrogen are practically |
the only products, as follows :
C,H, +0, = 2C0+2H,
C,H, +0, =2CO+ H
Bone has shown that the oxidation of the hydrocarbons at com-
paratively low temperatures proceeds by addition of oxygen
to the molecule and the successive formation of hydroxyl prod-
ucts—alcohols, aldehydes, formic acid and finally carbonic acid.
It appears that combustion at higher temperatures goes on in
the same way, and it has been found that oxygen has a much
greater affinity for the hydrocarbons than for hydrogen and car-
bon monoxide. For example, when detonating gas is exploded
with acetylene in the proportion O,H,+2H,+0O,, there is abso-
lutely no separation of carbon nor formation of steam, and practi-
cally the same thing holds good in the case of a mixture of
ethylene, hydrogen and oxygen corresponding to C,H, +H,+0.,.
In the presence of a hydrocarbon, carbon monoxide is attacked
by oxygen even less readily than is hydrogen. These observations
have an important bearing on the chemistry of flames. Hitherto
hydrogen has been considered as one of the most combustible of
gases, but in reality it is very much less so than the hydrocarbons.
It is probably not so much th eoriginal hydrocarbon as its hydrox-
ylated molecule which decomposes in ordinary flames, and experi-
mental evidence does not warrant the view, so often encountered
in scientific literature, that hydrocarbons are resolved into their
elements prior to being burnt.— Chem. News, cii, 809. Hu. L. w.
3. Supposed Chemical Distinction between Orthoclase and
Microcline.—Two ov three years ago the view was advanced by
Barbier that orthoclase differs from microcline in the fact that
the former contains traces of lithium and rubidium, while these
elements are not found in the latter. It appears, however, that
Ramage had previously found these alkali metals in a microcline
from Dalkley in Ireland, and that Vernadsky, somewhat later,
2
232 Scientific Intelligence.
found both rubidium and cesium in the bluish-green microcline
from Miask in the IImen mountains. In order to examine the
matter more thoroughly, Virnapsky and Revoutsky have now
examined a number of samples of microcline spectroscopically,
and have found the following elements present:
Miask, Iussian, K, Na, Rb, Li.
Arendal, Norway, Ba, K, Na, Rb.
Pike’s Peak, Colorado, K, Na, Rb, Li, Cs.
Hunttila, Finland, K, Na, Ba, Rb, Li.
Lojo, Finland, K, Na, Ca, Li (Rb?).
These results were obtained by heating fragments of the mineral
directly before the gas-oxygen blowpipe and observing~ the
spectrum of the flame. The results show that Barbier’s view is
evidently incorrect.— Comptes Rendus, cli, 1372. H. L. W.
4, Preparation of Argon.—G. CLauDE has found a convenient
way to prepare large quantities of argon. As a starting point he
uses the oxygen produced by the liquefaction of air, which
may be obtained 95 per cent pure, and with argon as its prin-
cipal impurity, amounting to about 3 per cent. This oxygen is,
therefore, about three times richer in argon than ordinary air.
The oxygen is absorbed by hot copper, and the nitrogen by hot
magnesium, only a small amount of the latter being required.
_A tube of hot copper oxide serves finally to oxidize any hydro-
gen that may have been formed from moisture present in the
materials employed.— Comptes Rendus, cli, 752. H. L. W.
5. Die Stellung der neueren Physik zur mechanischen Natur-
anschauung ; von Dr. Max Piano. Pp. 33. Leipzig, 1910 (8.
Hirzel).—This pamphlet contains a lecture given before the
eighty-second meeting of the German Scientists and Physicians,
held in Koénigsberg, last September. It deals with the Theory of
Relativity and with the philosophical views to which it leads in
the minds of many German mathematicians and physicists. To
the Anglo-Saxon mind, these views appear to touch the limits
of philosophical idealism. Ether and matter, in fact all substance,
is apparently discarded, and the physical universe consists of a
vacuum mitigated by the presence of the Principle of Least
Action, and Maxwell’s Equations; the “building stones,” of
which the physical world is constructed, are no longer material
particles but the so-called universal constants: the velocity of
light, the charge and mass of the electron, the “elementare Wir-
kungsquantum, ” etc. H. A. B.
6. History of the Cavendish Laboratory, 1871-1910. Pp.
x, 842. London, 1910 (Longmans, Green & Co.).—This volume
has been prepared in commemoration of the twenty-fifth anniver-
sary of Sir J. J. Thomson’s election to the Cavendish Professor-
ship of Physics in the University of Cambridge. It is the work
of several different authors, each period of the history of the
laboratory being treated by one who was intimately connected
with it during the time in question. Messrs. Fitzpatrick and
Chemistry and Physics. 233
Whetham deal with the building of the laboratory ; Professor
Schuster, with the Clerk Maxwell period ; Mr. Glazebrook, with
the years during which Lord Rayleigh was professor ; and Sir
J. J. Thomson, himself, gives a general survey of the past twenty-
five years. In chapters V to VIII the activities of the labora-
tory during these twenty-five years, are discussed in greater
detail. Professor Newall gives an account of the researches
conducted between 1885 and 1894 : Professor Rutherford recounts
the memorable achievements which marked the years 1895-1898 :
C. T. R. Wilson deals with the period from 1899 to 1902, and
N. R. Campbell completes the record to 1909. Chapter IX by
Professor Wilberforce of the University of Liverpool deals with
the development of the teaching of physics in Cambridge, a
development which has had great influence upon physics teach-
ing throughout the world. The volume closes with a list of
memoirs containing accounts of research performed in the Caven-
dish Laboratory, and a list of those who have worked there.
The volume cannot fail to be of great interest to all students
of physies ; it is a valuable contribution to the recent history of
the science, and a more appropriate way of celebrating Sir J. J.
Thomson’s twenty-fifth anniversary could scarcely have been
found. H. A. B.
7. The Principles and Methods of Geometrical Optics, espe-
cially as applied to the theory of Optical Instruments . by
Jamus P. C. Sourmany. Pp. xxiii, 626, with 169 figures. New
York, 1910 (The Macmillan Company).—This is a notable book
which surpasses all others in the English language treating of the
same subjects. The very great number of propositions in geo-
metrical optics are presented clearly, in a carefully studied
notation, which is, except in a few cases where other consider-
ations are of greater weight, consistent and lucid. The diagrams
are sufficient in number and very clear, with the too rare quality
of good taste in respect to all the details which determine the
character of such illustrations. Most excellent features of the
book are its bibliography and historical notes, which are very
complete. The only striking omission observed is that of the
admirably convenient—perhaps the most convenient of all—col-
lection of formulas for rigid computation of the constants of a
system of centered lenses by P. A. Hansen. These features
make the volume invaluable to one who seeks a knowledge of
what has been accomplished in this field during the three cen-
turies in which the problems of geometrical optics have been
continuously increasing in importance.
When we come, however, to consider the utility of the methods
and equations deduced in the text to the designer of optical
apparatus, we must give more restricted praise, since they empha-
size what is relatively unimportant in practice and thrust more or
less into the background those features which are essential.
Excellent examples in support of this assertion are afforded by
the only numerical calculations in the book, namely, the calcula-
234 Scientific Intelligence.
tions of some of the optical constants of a 12-inch Taylor tele-
scope objective. The geometrical data are given to three-figure
accuracy and are susceptible, perhaps, to a maximum of ten times
this precision. The calculations of focal lengths are carried out
to seven-figure accuracy, that is to some 1000 times the precision
warranted by the data; it is three or four hundred thousand
times as great precision as is deemed important by the designer
himself, if we infer that he expected to make the ratio of focal
length to aperture the standard for telescopes of this size. Never-
theless, this incommensurate labor of calculations is necessary in
order to deduce a sufficient value, to two figures only, of the
spherical aberration.
The other case is equally striking. The spherical aberration of
the same objective is calculated to a two-figure precision, which
is all that is of practical significance, by a tedious computation
with seven-figure logarithms by application of Seidel’s analysis
and with the disappointing error of one hundred per cent. These
considerations are enough to show that there is some radical
defect in a method which demands such efforts for such meager
returns. Probably there is no hope of material improvement
until the mathematician informs himself thoroughly as to the
relative importance of the magnitudes which enter his analysis
and then deals with the physical realities of wave surfaces and
refracting surfaces instead of the unnecessary fictions of rays
and of radii of lens surfaces. Cc. 8. H.
8. Chemische Krystallographie; von P.Grotu. Dritter Teil.
Aliphatische und Hydroaromatische Kohlenstoff-verbindungen.
Pp. iv, 804, mit 648. Text figuren. Leipzig, 1910 (Wilhelm
Engelmann).—This monumental work on Chemical Crystallog-
raphy begun in 1906 has now reached its third part, or as esti-
mated, three-quarters of the whole. It is devoted to the aliphatic
and hydroaromatic hydrocarbons. ‘The whole makes a work of
800 pages, with perhaps 1200 or more individual compounds,
whose crystallographic and optical constants are given with great
thoroughness. In a large number of cases the crystal form is
illustrated by figures. The congratulations of those immediately
interested are due to the veteran author for his success in carry-
ing through a work of such magnitude and importance.
II. Gerortoay anp Naturat History.
1. United States Geological Survey, Thirty-first Annual Re-
port (1909-1910) of the Director, GrorcEe O. Suite. Pp. 131
with two plates. Washington, 1911.—This report contains a
statement of the work done by the various divisions of the
Survey during the fiscal year ending June 30, 1910. The pro-
gress in land classification consisted in, first, the preparation of
withdrawals covering power sites and coal, oil, gas, and phos-
phate lands ; second, the classification of withdrawn lands and
Geology and Natural History. 235
restoration of such as were found to be not underlaid by valuable
deposits. The work involves also the performance of various
executive and advisory functions connected with the classification
and valuation of the public lands.
The mining and technologic work of the Survey, which in the
last few years has assumed large importance, was transferred on
July 1, 1910, to the newly established Bureau of Mines (see v. xxx,
pp. 292, 419). Thus another child of the Geological Survey,
having grown to adult proportions and demonstrated its useful-
ness, has been launched on an independent career. No small part
of the great value which the Survey has been to the nation con-
sists in the foresight, efficiency, and high scientific grade with
which new branches of government work have been developed
under the care of that organization. The increase in the corre-
spondence of the Geological Survey and in the distribution of its
publications is a measure of the increasing appreciation by the
people of the work which is done. The correspondence increased
more than 20 per cent over that of the previous year and the
total number of reports and maps distributed has increased more
than 13 per cent. The publications of the Survey during the
year measure a part of its returns for the money expended.
They consisted of 4 professional papers, 47 bulletins, 18 water
supply papers, one volume on mineral resources, 6 geologic folios
and 94 topographic maps. J. B.
2. Publications of the U. 8S. Geological Survey.—Recent
publications of the U. 8. Geological Survey are noted in the fol-
lowing list (continued from vol. xxx, p. 417). The thirty-first
Annual Report of the Director is noticed above.
Torocraruic ATLAS.—Seventy-three sheets.
Fouro, No. 174. Johnstown Folio, Pennsylvania; by W. C.
PuatEen. Pp. 15, with 1 columnar section, and 3 maps.
Sacramento Folio, California; by W. LinpGren. Pp. 3, 4
maps.
ProFreEssionAL Parser, No. 72. Denudation and Erosion in
the Southern Appalachian Basin ; by Leontpas C. Gurenn. Pp.
137, 21 plates, 1 figure.
Buxtietins.—No. 430. Contributions to Economic Geology
(Short Papers and Preliminary Reports, in part earlier issued as
separates.) 1909. Part I. Metals and Nonmetals except Fuels.
C. W. Hayrs and Watpremar LinpereEn, geologists in charge.
Pp. 653, 14 plates, 75 figures.
No. 431—A. Advance Chapter from Contributions to Eco-
nomic Geology, 1909. Petroleum and Natural Gas; by A. G.
Lronarp, H. E. Grecory, C. W. Wasnpurne, and RosBertr
ANDERSON. Pp. 83, 3 plates, 1 figure.
No. 433. Geology and Mineral Resources of the Solomon and
Casadepaga Quadrangles, Seward Peninsula, Alaska ; by Puivie
S. Smiru. Pp. 234, 16 plates, 26 figures.
No. 436. The Fauna of the Phosphate Beds of the Park City
Formation in Idaho, Wyoming, and Utah; by Groner H. Girry.
Pp. 82, 7 plates.
236 Scientific Intelligence.
No. 440. Results of Triangulation and Primary Traverse for
the years 1906, 1907, and 1908. R. B. Marsuarn, chief geog-
rapher. Pp. 688, 1 plate.
No. 441. Results of Spirit Leveling in Alabama, Georgia,
North Carolina, South Carolina, and Tennessee, 1896 to 1909,
inclusive. R. B. Marsuatt, chief geographer. Work done in
cooperation with the State of Alabama during 1899 to 1905,
inclusive ; with the State of North Carolina during 1896 and
from 1902 to 1909, inclusive. Pp. 145.
No. 442. Mineral Resources of Alaska. Report on Progress
of Investigations in 1909; by Atrrep H. Brooke and others.
Pp. 426, 7 plates, 8 figures.
No. 470-A. Advance Chapter from Contributions to Eco-
nomic Geology, 1910. Phosphates in Montana; by Hoyt S.
GatE. Pp. 9, 2 figures.
Warer Suppty Parers.—No. 254. The Underground Waters
of North-Central Indiana ; by SrepHen R. Capps, with a chap-
ter on The Chemical Character of the Water, by R. B. Doux.
Pp. 279, 7 plates, 12 figures.
Nos. 262, 264.—Surface Water Supply of the United States, 1909
[prepared under the direction of M. O. Lerentron]. No. 262.
Part II, South Atlantic and Eastern Gulf of Mexico; by M. R.
Hatt and R. H. Botster. Pp. 150, 5 plates. No. 264. Part
IV, St. Lawrence River Basin ; by C. C. Covert, A. H. Horton
and R. H. BotstErr. Pp. 130, 5 plates.
3. Bureau of Mines, Joseru A. Hormes, Director.—Four
additional bulletins have been recently issued ; these are as fol-
lows: Bulletin 2, North Dakota Lignite as a Fuel for power-
plant Boilers ; by D. T. Ranpati and Henry Kreisincrer. Pp.
42, 1 plate, 7 figures. Bulletin 3, The Coke Industry of the
United States as related tothe Foundry; by Richarp MoLtpENKE,
Pp. 32. Bulletin 4, Features of Producer-Gas Power—Plant
Development in Europe; by R. H. Fernarp. Pp. 27, 4 plates,
7 figures. Bulletin 5, Washing and Coking Tests of Coal, at the
Fuel-Testing Plant, Denver, Colorado, July 1, 1908, to June 30,
1909 ; by A. W. Berpen, G. R. Detamarsr, J. W. Grovus, and
K. M. Way. Pp. 62, 1 figure.
Miners’ Circulars Nos. 1 and 2 have also just been issued ; they
are the first of a series to be written in plain, non-technical language
for the benefit of the miner. They contain the names of the per-
missible explosives tested by the bureau at its Pittsburg station
up to November 15, 1910, and gives precautions as to their use.
4. Florida State Geological Survey. Third Annual Report,
1909-1910, EK. H. Srtiarps, State Geologist. Pp. 397 with
numerous plates and figures. Tallahassee, Fla., 1910.—This
report, like the preceding of the series, is of high scientific
as well as practical value. ‘The scientific interest lies in the
unique character of the geologic province of Florida as com-
pared with other portions of the United States and the way in
which the subjects have been treated. The value to the citizens
Geology and Natural History. 237
of Florida lies in the information which it contains on the mineral
and water resources of the State. The volume contains, besides
the administrative report and index, the following papers: A
Preliminary Paper on the Florida Phosphate Deposits, by E. H.
Sellards ; Some Florida Lakes and Lake Basins, by E. H. Sel-
lards ; The Artesian Water Supply of Eastern Florida, by E. H.
Sellards and Herman Gunter; A Preliminary Report on the
Florida Peat Deposits, by Roland M. Harper. J.B:
5. The Badland Formations of the Black Hills Region ; by
Crropnas C. O?Harra. 144 pp., 50 pls., 20 figs. South Dakota
School of Mines, Bulletin No. 9, Department of Geology. Rapid
City, South Dakota, November, 1910.—The “ badlands” of South
Dakota form one of the most interesting physiographic sub-
provinces in the world, and taken in connection with the Black
Hills, forms a type area which in many respects is unique. While
the structure and stratigraphy are not complicated, yet the details
are so important as to fully justify the prominent place given to
this area in the literature. Heretofore students have had to
search through widely scattered technical reports in order to
obtain information regarding the origin and topographic develop-
ment of the badlands, as well as of the large and interesting col-
lection of fossils. Thanks to Professor O’Harra, we now have a
single volume accessible to students and amateurs wishing to
become acquainted with this country,—a volume which does not
require advanced scientific training to understand. From an
educational standpoint the publication is, therefore, abundantly
justified in spite of the absence of essential facts and interpreta-
tions new to science.
6. West Virginia Geological Survey, I. C. Wuirr, State
Geologist. Bulletin 2. Pp. 358. Morgantown, 1911.—Follow-
ing Bulletin No. 1, which gives a bibliography of the state, the
West Virginia Survey has now issued a volume containing tables
of levels and distances, and also coal and coke analyses. The
levels are compiled from records of the State and Federal Sur-
veys, and have been supplemented by data collected by the vari-
ous West Virginia railways. The analytical tables contain
results of tests of coal made from all the economic horizons of
importance,—namely, the Pottsville, Kanawha, Allegheny, Cone-
maugh, Monongahela, and Dunkard series. The estimated coal
production for 1910 is 65,000,000 short tons. H. E. G.
7. New Zealand Geological Survey, J. M. Bell, Director.
Bulletin No. 9 (New Series), The Geology of the Whatatutu
Subdivision, Raukumara Division, Poverty Bay ; by Jamus
Henry Apams. 1910. Pp. ili and 46, 3 ills., 5 maps.—In age
the rocks included within this subdivision are upper Miocene and
consist of shales, argillites, sandstones, with coarse sandstones
and conglomerates in the upper portion. Pumiceous deposits,
possibly of Pliocene age, also occur. An interesting problem is
presented by the fact that many of the igneous pebbles in the
conglomerate are unlike any rocks thus far discovered in the
Am. Jour. Sci.—FourtTH SERIES, VoL. XX XI, No. 183.—Marcu, 1911.
17
238 Scientific Intelligence.
north island of New Zealand. The fossils collected in this area
have been studied by Professor Marshall of Otago University.
He finds that out of a total of forty-four species of mollusca
recent species number twelve, and the conclusion is reached that
the strata are. Upper Miocene in age rather than partly Cretace-
ous, aS previously assumed. In the Whatatutu area the terraces
developed along the streams at 200 and 400 feet give a clue as to
the amount of elevation since the end of Miocene time. A much
dissected coastal plain at an elevation of 3000 feet is indicated by
the structure and attitude of Tutamoe ridge. Owing to the
economic importance of this field the structure has been studied
in detail. It is found that the rocks have been folded into broad
anticlines and that accompanying the folds are faults of slight dis-
location. The existence of fourteen oil seeps attracted attention
to the Waitangi hill as early as 1874, but later developments have
not led to discoveries of oil or gas in quantities sufficiently large
to be of commercial importance.
Bulletin No, 10 (New Series), The Geology of the Thames
Subdivisions, Hauraki, Auckland ; by Coun FRAsER. 1910.
Pp. ii and 129, 9 ills., 19 maps and sections.—The Thames section
in the northern island of New Zealand was brought into promi-
nence by the discovery of gold in 1865. By 1871 the production
had reached about $5,940,000, and this largely from one bonanza.
The production at the present time is below the $500,000 mark,
and the main hope is in exploiting lower levels. The oldest
rocks of the area, the Tokatea Hill series, consist of argillites and
graywackes of pre-Jurassic age. The Manaia Hill series (Jurassic)
overlies uncomformably the older terranes. A long interval, dur-
ing which folding and faulting occurred and a submarine topog-
raphy was developed, elapsed between the Jurassic and the Eocene.
Three periods of volcanic eruptions are revealed by an examina-
tion of the Tertiary strata. The upper Eocene and Miocene
volcanics consist of andesitic and dacitic tuffs, breccias, con-
glomerates and lavas, while the Pliocene eruptions were rhyolitic
in nature. Large and small folds have been observed in the dis-
trict, and have been found to be of direct economic importance.
The great Moanataiari fault with a down-thrust of 595 feet is
represented topographically by a partially dissected fault scarp.
Pages 50-115 of this report are devoted to detailed descriptions
of existing mines and mining areas. ; H. E. G.
8. Geological Survey of Western Australia, Bulletin No.
33, Geological Investigations in parts of the Gascoyne, Ashbur-
ton and West Pilbara Goldfields ; by A. Gipp Marrianp. 1909.
Pp. 77, 13 maps and 65 figures.—The area covered by this report
is the extreme western portion of Australia including the coast
line from Port Hedland to the mouth of the Wooramel River.
The geological sketch-map shows the Gascoyne beds (Carbonifer-
ous) well developed in the lower Gascoyne River ; the Bangemall
beds (Nullagine ?) from Frederick River to Mount Flora; and
the Ashburton beds (age undetermined), chiefly in the neighbor-
hood of Ashburton and Hardey Rivers. There are also small
Geology and Natural History. 239
areas of pre-Carboniferous granite and gneiss. The relations and
character of the formations near the coast line are revealed by a
3011 foot well at Carnarvon, which shows 1211 feet of Mesozoic,
1650 feet of Carboniferons. ‘The Carboniferous section in the
Arthur River valley consists of (1) grits and fine conglomerate,
(2) fossiliferous limestone, (3) limestone conglomerate, (4) gla-
cial bowlder bed, (5) sandy and flaggy limestones. This glacial
bowlder bed is well exposed at a number of localities and in the
Wyndham River valley contains Spirifera, Productus, Polyzoa,
and Aviculopecten. The Carboniferous series as a whole rests
upon metamorphosed sedimentary rocks of unknown age. Owing
to the economic importance of this part of West Australia some-
what detailed studies of structural relations were made. In the
vicinity of Bangemall slates, limestones, quartzites and diabase
are arranged in a denuded anticlinal fold and are intersected by
numerous quartz reefs. Mount Augustus, one of the most con-
spicuous scenic features of West Australia, was found to be a
sharp monoclinal fold of schist and conglomerate. Both normal
and thrust faulting are revealed at Coorabooka Gap, and the
position of this gap as well as the arrangement of the drainage
lines suggests interesting physiographic studies. In the Uaroo
copper district of Ashburton the rocks are sedimentaries of
unknown age and have undergone deformation since mineraliza-
tion.
A chapter on petrography by J. Allan Thomas contains a dis-
cussion of dolomite and cherts, pyroxenites and amphibolites,
together with conclusions regarding magmatic sequence. Sixty-
nine slides are described in detail accompanied by a list of eighteen
analyses. While this bulletin is chiefly devoted to economic
studies, it adds considerable to the meager information regarding
the ceology of this interesting country.
Bulletin 38, The Irwin River Coalfield ; by W. D. Came-
BELL, 1910. Pp. 101, 7 plates and 53 figures.—The pre-Car-
boniferous rocks of the Irwin River district are gneisses and
granites “traversed by dikes of diabase, basalt, and norite, and
lodes of lead and copper in addition to quartz veins.” This
crystalline complex was greatly eroded before the deposition of
extensive beds of quartz conglomerates and submarine tuffs of
pre-Carboniferous age. The Carboniferous rocks are fossiliferous
and consist of clays, shales, sandstones and limestones. One
important stratum is the glacial bewlder bed which has been
recognized at several localities in Western Australia. In the area
under discussion this bowlder bed is found within the Carbonifer-
ous and not at its base. Jurassic strata, 300 feet in thickness and
containing lignite, rest upon the denuded surface of the Car-
boniferous. ‘Tertiary limestones and sandstones seems to overlie
unconformably the Jurassic rocks of the Hutt River district.
H. E. G.
9. Paleontological Contributions to the Geology of Western
Australia. Geol. Surv. Western Australia, Bull. 36, Pt. III,
pp. 133 and 12 pls. 1910.—A series of eight papers is here
240 Scientific Intelligence.
included, as follows :—(1) Hinde on isolated sponge spicules
that are “newer than the Cretaceous”; (2) Arber on some Juras-
sic plants; (3) Etheridge on 19 Oolitic invertebrates ; (4) Glau-
bert on a fossil cave marsupial, Sthenwrus occidentalis, (5) on a
list of West Australian pre-Tertiary fossils known to the end
of 1908, (6) on Paleozoic fossil plants, (7) on peel fossils,
and (8), on Cretaceous chalk and fossils. c. 8.
10. Report of the Vermont State Geologist for 1909-1910 ;
by Grorer H. Perkins. Pp. xii, 361, pls. 71. 1910 [Jan. 1911].
—The volume opens with an account of the History and Condi-
tions of the State Cabinet, by the State Geologist. The granites
of the state are described by T. Nelson Dale, in an ar ticle which
is practically a reprint of a bulletin of the U. 8. Geological Sur-
vey. C. H. Hitchcock has a chapter on the Surfacial Geology of
the Champlain Basin and Percy E. Raymond brings together all
that is known about the trilobites of the Chazy formation in
Vermont. The latter comprise 36 species, all of which are illus-
trated. Professor Perkins describes the geology of the Burling-
ton Quadrangle and Professor Seely has a preliminary report on
the Geology of Addison County. Asbestos in Vermont is treated
by C. H. Richardson and the mineral resources by the State
Geologist. oS}
11. A Contribution to the Geologic History of the Floridian
Plateau ; by Tuomas Waytanp Vaucuan. Carnegie Institution
of Washington, Publication 133, pp. 99-185, 15 pls., 6 text figs.
:910.—This well written and very interesting work should be
studied by all stratigraphers and geologists because here we have
worked out with care the present conditions of deposition and
geologic work now going on in the Floridian region as a basis
toward a proper interpretation of the Tertiary history of the
peninsula. The author first describes the topography of the
Floridian Plateau and then goes into considerable detail in regard
to the marine bottom deposits forming in the bays and sounds
behind the keys. Limestones are here being made by precipita-
tion from the sea water as amorphous calcium carbonate and are
apparently not of detrital origin. It is a soft ooze into which a
rod can be forced down ten feet or more ; in fact, the depth of
this soft material has not been determined.
Vaughan then discusses the transporting agents (currents and
winds) of the Florida coast and their effects. The smaller half
of the work treats of the geologic history of the Floridian Pla-
teau. The history is worked out in some detail and the book is
abundantly illustrated by maps, one of which presents the geolo-
gic formations of the state. There are also many photogravures
of vegetation, sea shores, and geological deposits. ©. Ss.
12. Recent Discoveries Bearing on the Antiquity of Man in
Europe ; by Gnorck Grant MacCurpy. Smithsonian Report
for 1909, pages 531-583, pls. 1-18. 1910.—The author brings
together here the accounts of the many wonderful discoveries
that have been made in the past ten years bearing upon the
Geology and Natural History. 241
antiquity of man in Europe. It seems that the oldest undisputed
flint implements of man go back to the Upper Miocene and the
oldest bone, a jaw (Homo heidelbergensis), has been found near
the base of the Quaternary. Man, as man, has lived, therefore, in
western Europe at least throughout the entire Glacial period,
developing into Homo primigenius, a stocky robust type, of low
stature, and with relatively short arms and legs much as in the
Eskimo. In the Upper Quaternary, or at least 30,000 years ago,
there came into western Europe, probably from the East, a more
intellectual race of men, the Aurignacians, and it is these people
who sculptured, engraved, and frescoed the walls of the caverns
and their tools and ornaments. Their descendants, the Magda-
lenians, introduced the rudiments of writing, and this seemingly
was more than 10,000 years ago, if we may judge by the time
standards accepted by geologists for the duration of time since
the last glacial climate. The negroid people also passed into
western Europe, possibly by way of Gibraltar, probably soon
after the arrival of the Aurignacians. It is also becoming more
and more certain that man did not originate out of any of the
existing ape stocks, but rather that the human stock is as old as
any of the tailless primates. According to Professor Klaatsch,
Homo primigenius is more closely related to the gorilla of
Africa, while Homo aurignacensis bas closer affinities with the
chimpanzee of Asia. All of these stocks had their origin in the
far distant past, certainly not less than one million years ago.
C.us!
13. On the Fossil Faunas of St. Helen’s Breccias ; by HENRY
S. Wittrams. Trans. Royal Soc. Canada, III, pp. 205-246, pls.
1-4, 1910.—The Devonian faunas of St. Helen’s island near Mon-
treal have long perplexed students of fossils as to the exact age
of these fossil horizons when compared with similar formations
in New York. Professor Adams of McGill University had quar-
ried out from three isolated limestone masses underlying the
agglomerates of the island about three-fourths of a ton of mate-
rial which Williams has here subjected to a detailed study. The
author, therefore, has had far greater advantages than any other
paleontologist studying these early Devonian biotas.
The older fauna of about 30 species is of Helderbergian age
and apparently of about Becraft time. Williams names it the
Gypidula pseudogaleata fauna. The age is clearly seen in the
following species: Schizophoria multistriata, Stropheodonta
planulata, Gypidula pseudogaleata, Camaroteechia ventricosa,
Spirifer concinnus, and Meristella princeps. The faunal rela-
tions are clearly with New York and nothing exactly like it is
known farther northeast in the Gaspé region.
The younger fauna is from another isolated limestone mass,
and is the one furnishing much new information. Williams calls
it the Spirifer arenosus fauna and ascribes to it 25 species. The
more striking forms are: 1 Dalmanella subcarinata, 2 Hodevo-
naria hudsonicus gaspensis, 3 Chonetes striatissimus (near C. can-
242 Scientific Intelligence.
adensis), 4 Rhynchonellu eminens, 5 Eatonia peculiaris, 6 &. cf.
whitfieldi, 7 Spirifer arenosus, 8 S. gaspensis, 9 S. montrealensis
n. sp. (look almost like genuine S. granulosus), 10 S. cumber-
landice, 1\ 8S. pennatus helene, 12 Metaplasia pyxidata, and 13
Cyrtina rostrata. To these must be added 14 Chonostrophia
montrealensis described by Schuchert but not seen by Williams.
In the light of our American Devonian assemblages we see here
a very much mixed fauna. Numbers 1 and 4 are Helderbergian
forms, while 9 and 11 are decided early Hamilton reminders.
The remainder of the fauna suggests later Oriskanian. In the
Oriskany of Cumberland, Md., the reviewer has also collected
shells of the type of 8S. montrealensis, but these are by no means
so near the Hamilton S. granulosus as seemingly are the~St.
Helen’s specimens. Further, the reviewer, while collecting on
the island in 1900, noted that the two species 9 and 11 occurred
together, but he then saw no other forms in the “flat block of
limestone” in the agglomerate. For this reason he held their
age to be Onondaga. It was Mr. Ardley who directed him to
these fossils and associations and Williams’ S. arenosus fauna of
25 species has since been quarried out of this same block. The
majority of the fauna is undoubtedly Oriskanian and yet the
aspect is more recent than any fauna of this series in the Appa-
lachian—New York area.
Williams clearly recognizes that the St. Helen’s Spirifer are-
nosus fauna is unique and believes it to be somewhat younger
than any Oriskanian fauna of New York but older than the
Onondaga. Faunas of the same age as that of St. Helen’s but of
another basin, linking more directly with the European Coblen-
zian, he holds are those of Nictaux, Nova Scotia, York river,
Gaspé, and Moose river, Maine, in which “ are seen traces of the
Hamiltonian magnafauna.” He further holds that the
Onondaga fauna came in along the western side of the Cincin-
nati axis, finally spreading to the St. Lawrence valley and there
met and mixed with the northern Atlantic fauna “ on the Ameri-
can border at the time of the departure of the Oriskanian ele-
ment rather than at the opening of the Hamilton epoch. This
interpretation is in harmony with the mingling of these same two
magnafaunas [lower Devonian and Hamilton] in the lower
Devonian (Coblenzian) of Europe.”
The reviewer agrees with Williams that the Oriskanian faunas
of the maritime “province of eastern Canada are considerably
Coblenzian in faunal aspect and that the Hamilton aspect appears
earlier in this European assemblage, but he still believes that the
York river fauna near the base of the Gaspé sandstone as
described by Clarke (1908) is considerably younger than the
Spirifer arenosus fauna, for the reason that the latter assemblage
at Gaspé occurs at a very much lower horizon, in fact, at the
base of the Grande Gréve limestone. C. SCHUCHERT.
14. Paleontologia Universalis, ser. JI, fasc. II, 46 sheets,
July 26, 1910.—In this new part of the Palzontologia Univer-
Geology and Natural History. 243
salis there are redescribed and well figured 20 Lamarckian species
of mollusks and corals described by him between 1801-1819.
The studies were made by Dollfus, Boussac, Pervinquiére,
Cossmann, Lemoine, and Germain. CS:
15. Hine Botanische Tropenreise, Indo-Malayische Vegetations-
bilder und Reiseskizzen ; by Prof. Dr.G. Hasmrianpr. Second
edition. Pp. viii, 296; 12 plates and 48 text-figures. Leipzig, 1910
(Wilhelm Engelmann).—The first edition of Professor Haber-
landt’s book appeared in 1893 and soon became widely and favora-
bly known on account of its graphic and satisfactory descriptions
of various types of tropical vegetation. The work is based on the
autbor’s personal observations, most of which were made during
a visit to the famous botanical garden at Buitenzorg in Java.
Among the many interesting chapters those dealing with tropical
trees, tropical leaves, vines, epiphytes, and mangroves should per-
haps be especially mentioned, although several of the others treat
subjects of equal importance. The twelve plates in the second
edition are all new; nine are made from photographs, while the
three others, in color, are reproduced from water-color sketches
by the author. A. W. E.
16. Plant Anatomy, from the Standpoint of the Development
of the Tissues, and Handbook of Micro-technic; by Wittiam
Cuase Srevens, Professor of Botany in the University of
Kansas. Second edition. Pp. xv, 379, with 152 text-figures.
Philadelphia, 1910 (P. Blakiston’s Son & Co.).—The first edition
of this excellent work appeared in 1907, and was reviewed in
this Journal for April, 1908 (xxv, 363). The most important
new matter in the second edition is the, chapter on reproduction,
which includes discussions of the following topics : the reduction
of chromosomes, the behavior of hybrids interpreted according to
Mendel’s Laws, the bearers of hereditary characters, and the
theory of pangeneic exchange. A. W. E.
17. A Text-Book of Botany and Pharmacognosy ; by Henry
KrarmMeEr, Ph.D., Professor of Botany and Pharmacognosy in the
Philadelphia College of Pharmacy. Fourth edition. Pp. viii,
888, with 344 figures, mostly in the text. Philadelphia and Lon-
don, 1910 (J. B. Lippincott Company, price $5.00 net).—The first
edition of the present text-book appeared in 1902 and contained
384 pages ; the second edition, of 1907, had already been enlarged
to 840 pages; while the third edition, of 1908, numbered 850
pages. The rapid succession of new editions proves conclusively
that there is a strong demand for a work of this character by
students of pharmacognosy and that the book in question is well
fitted to their needs. In the first part, entitled ‘‘ Botany,” the
morphology and classification of plants are clearly treated, with
special reference to medicinal plants. In the second part, “ Phar-
macognosy,” detailed descriptions of important drugs are given,
their minute structure being fully illustrated by figures. The
third and fourth parts are much shorter than the others. The
third deals with “Reagents and Microtechnic,” and the fourth,
244 Scientific Intelligence.
which is new to this edition, discusses “ Micro-Analysis.” The
eighteen figures illustrating the fourth part are reproduced from
microphotographs of erystals, A.W. EB.
18. Biology: general and medical; by Joseru McFaruann,
M.D. Pp. 440, with 160 illustrations, Philadelphia and Lon-
don, 1910 (W. B. Saunders Company).—This book differs widely
from most of the other elementary text-books in biology, which
have recently appeared, in subordinating the morphological
almost entirely to the physiological aspects of the subject. It is
essentially a treatise on general physiology, with such descrip-
tions of the anatomical structures as are absolutely necessary for
the understanding of the processes concerned. For elementary
courses in colleges and universities where large numbers of-stu-
dents elect biology as a general culture study, and where the
laboratory work is necessarily confined mainly to the morpholog-
ical side of the subject, the book forms an admirable supplement
to the laboratory and lecture portions of the course.
The immediate adoption of this book by some of our largest
universities shows the need that has been felt for a work of this
kind. There are, however, certain defects which appear when
the book is subjected to the test of the classroom. Numerous
instances of statements that are misleading or actually erroneous
are brought to light, and complaint is made that an unnecessarily
formidable array of technical medical terms is introduced. The
general excellence of the plan of treatment, however, more than
compensates for such emendations as the experienced teacher is ~
required to make in the classroom.
The properties of living matter, cells, and their arrangement
in different groups of organisms, reproduction, ontogenesis, con-
formity to type, divergence, structural and blood relationships,
parasitism, infection and immunity, mutilation and regeneration,
grafting, senescence, decadence and death, indicate the subjects
of the principal chapters into which the book is divided.
W. Rs,.0.
Ill. Miscernanrous Sorentiric InreLLicENoE.
1. Carnegie Institution of Washington. Year-Book, No. 9.
1910. Pp. xvi, 258, 5 plates. Washington, January, 1911.—
Especial interest is connected with the appearance of the ninth
Year-Book of the Carnegie Institution because of the recent gift ©
by Mr. Carnegie of an additional $10,000,000 to the Institution,
making its total fund equal to $25,000,000. This addition to its
resources is particularly opportune at this time, since in the pres-
ent volume Dr. Woodward calls attention to the serious effect
of increase of prices as limiting the future income available for
promoting research. The Institution was organized in 1902 and
since that time the magnitude and importance of the work it has
accomplished are truly remarkable. The total amount of money
Miscellaneous Intelligence. 245
expended up to date is $4,590,000, of which a little more than
one-half has been applied directly to the prosecution of research,
and about one-third is represented in land, buildings, and other
permanent forms; about 8 per cent has been used for expenses
of administration and somewhat less for publications. Twelve
hundred individuals have contributed towards the researches and
publications undertaken by it. The volumes already published are
167 in number, and aggregate more than 40,000 printed pages.
Twenty-five additional volumes are now in press : further, some
1200 shorter papers have been contributed to current scientific
periodicals by those working under the Carnegie foundation.
Of particular importance in the work of the past year is the
occupation of the new administration building, which was dedi-
cated in December, 1909, and has proved in all respects a thor-
oughly satisfactory and dignified permanent home for the
Institution. During 1910, also, the non-magnetic ship Carnegie
completed its first voyage of 8,000 miles with important results,
and a second cruise, planned to last three years, was begun on
June 29th : at present the vessel is off the coast of Brazil. As
is now generally known, there are ten departments, to the sup-
port of which the income of the Institution is chiefly devoted,
the total sum appropriated towards them amounting to $450,000.
A considerable number of minor grants have been made in addi-
tion, although these are few as compared with the situation
earlier in the history of the Institution. For these last, the
ageregate amount allotted was about $70,000. In the opening
pages of the present volume, Dr. Woodward gives a very interest-
ing résumé of the investigations of the present year, particularly
in connection with the ten lines of work already alluded to. This
same subject is discussed in detail on pages 53-204 by the
Directors of the different departments. It is impossible here to
go into details in regard to these special lines. Some of the
most interesting concern the work of the Geophysical Labora-
tory, under Dr. A. L, Day; the Department of Marine Biology
at Tortugas, Florida, under Dr. A. G. Mayer; and the Solar
Observatory at Mt. Wilson, California, now represented by W.S.
Adams, Acting Director during the absence of Professor Hale.
Dr. Bauer also gives a summary of the work accomplished in ter-
restrial magnetism, with a chart showing the projected cruise of
the “ Carnegie ” alluded to above. The volume closes with brief
statements, thirty-four in number, as to the results accomplished
in the various lines of investigation represented by the minor
grants.
2. Publications of the Carnegie Institution.—Recent publica-
tions of the Carnegie Institution are noted in the following list
(continued from vol. xxx, 295):
No. 74. The Vulgate Version of the Arthurian Romances,
edited from manuscripts in the British Museum; by H. Oskar
Sommer. Volume III. Le Livre de Lancelot del Lac. Part I.
Pp. 430.
246 Scientific Intelligence.
No. 88. Dynamic Meteorology and Hydrography; by V.
BserKNES and different collaborators. Part I, Statics by V.
Bserknes and J. W. Sanpstrém. Pp. 146 and appendixes, 31
figures.
No. 119. Determination of the Solar Parallax, from photo-
graphs of Eros made with the Crossley Reflector of the Lick
Observatory, University of California ; by Cuartes D. Perrine,
Harotp K. Patmer, Freperic C. Moorr, Apretarwe M. Hose.
Pp:98.- See ip. 153.
No. 120. The Symmetric Function Tables of the Fifteenthic
including an Historical Summary of Symmetric Functions as relat-
ing to Symmetric Function Tables; by Froyp Fiskr Decker,
Pp. 16, 5 large tables.
No. 127. Superheated Steam in Locomotive Service; by
WiturAm F. M. Goss. Pp. 144, 1 plate, 108 figures. i
No. 130. A Study of the Absorption Spectra of Solutions of
Certain Salts of Potassium, Cobalt, Nickel, Copper, Chromium,
Erbium, Proseodymium, Neodymium, and Uranium as affected
by Chemical Agents and by Temperature ; by Harry C. Jones
and W. W. Srrone. Pp. ix, 159, 98 plates.
No. 132. Department of Marine Biology, ALrrep G. Mayer,
Director. Papers from the Tortugas Laboratory. Volume III,
pp- 1-152, 17 plates, 38 figures. Contains twelve papers by dif-
ferent authors.
No. 132. Department of Marine Biology, ALFrep G. Mayer,
Director. Papers from the Tortugas Laboratory. Volume IV,
pp. 1-186, 43 plates, 17 figures. Contains three papers by Henry
S. Pratt, Epwin Linton and T. W. Vaueuan. Pp. 185.
No. 185. Researches upon the Atomic Weights of Cadmium,
Manganese, Bromine, Lead, Arsenic, Iodine, Silver, Chromium,
and Phosphorus ; by Grecory Pav Baxter, in collaboration
with M. A. Hines, H. L. Frevert, et al.
No. 136. Metabolism in Diabetes Mellitus ; by Francis G.
Benepict and Erxriotr P. Josuin. Pp. vi, 234.
No. 141. The Water Balance of Succulent Plants; by D. T.
Macpoueat and E. 8. Spatpine. Pp. iii, 77, 8 plates.
3. Annual Report of the Board of Regents of the Smith-
sonian Institution, showing the operations, expenditures and
condition of the Institution for the year ending June 30, 1909.
Pp. x, 751, 73 plates, 1 map. Washington, 1910.—The Annual
Volume of the Smithsonian Institution for 1909 opens with the
Report of the Secretary, Dr. Walcott, issued in advance about a
vear since, and at that time noticed in this Journal (vol. xxix, 196).
It also contains, in the General Appendix (pp. 119-751), the usual
series of well-selected papers devoted to a wide range of subjects,
many of them republished from foreign journals. These papers are
all more or less popular in method of presentation, so that they
appeal to the intelligent public, which finds here a remarkable
résumé of recent scientific progress not to be found in so con-
venient a form elsewhere. Among them may be mentioned one
on Radio-telegraphy by J. A. Fleming ; another by Marchis on
Miscellaneous Intelligence. 247
the production of Low Temperatures and Refrigeration ; on the
return of Halley’s Comet, by W. W.Campbell ; on the British
Antarctic Expedition of 1909, by Lieut. Shackleton; on the
Antiquity of Man in Europe, by G. G. MacCurdy ; on Panama
and its People, by Eleanor Y. Bell; on the Natural Resistance
to Disease, by Simon Flexner.
The following are recent Bulletins issued by the Bureau of
Ethnology of the Smithsonian Institution:
No. 30. Handbook of American Indians North of Mexico ;
edited by Freprrick Wess Hopner. In two parts. Part 2,
N-Z. Pp. iv, 1221. See vol. xxiv, p. 91.
No. 37. Antiquities of Central and Southeastern Missouri, by
GERARD Fowxer. (Report on Explorations made in 1906-07
under the auspices of the Archzological Institute of America.)
Pp. vii, 116, 19 plates, 20 figures.
No. 45. Chippewa Music; by Frances Densmore. Pp. xix,
216, 12 plates, 8 figures.
No. 49. List of Publications of the Bureau of American
Ethnology with Index to Authors and Titles. Pp. 32.
4. Publications of the Allegheny Observatory of the Univer-
sity of Pittsburgh ; edited by Frank ScuLesincEer.—The follow-
ing have recently been issued :
Vol. I, No. 23. The Orbits of the Spectroscopic Components
of v Andromede; by Frank C. Jorpan. Pp. 191-201. Also
title page and contents of volume I.
Vol. If. No.1. A Description of the Mellon Spectrograph ;
by Frank Scuiesincer. Pp. 1-12, two figs. No. 2. On the
Relative Motions in 61 Cygni and similar Stars; by Frank
ScHLESINGER and Dinsmore Atrer. Pp. 13-16. No. 3. The
Orbits of the Spectroscopic Components of « Herculis ; by Ropurr
H. Baxer. Pp. 17-23. No, 4. The Orbit of I H. Cassiopeiz ;
by Roxserr H. Baker. Pp. 25-28. No. 5. The Orbit of 30 H.
Urs Majoris; by Rosrerr H. Baker. No. 6. The Orbits of the
Spectroscopic Components of 57 Cygni; by Roprerr H. Baker.
No. 7. Further Observations of 9 Aquile ; by Roperr H. Baker.
No. 8. The Orbit of 7 Andromede ; by Frank C. Jorpan. No.
9. The Hclipsing Variable « Herculis; by Frank ScuLesincEeR
and Rosrerr H. Baker. Pp. 51-62. No. 10. The Spectrum and
Orbit of o Persei ; by Frank C. Jorpan. Pp. 63-71.
5. Bref och Skrifvelser af och till Carl'von Linné. Part 1V.
Pp. iv, 365. Stockholm, 1910.—The fourth part of the corre-
spondence of Linnzeus (see vol. xxix, 200), published under the
auspices of the Upsala University, contains a very interesting
series of letters to and from Abraham Bick, dating from 1741 to
1755.
6. Seismological Society of America.—The Seismological
society, of which Prof. J. C. Branner is president, has decided
to issue a Bulletin, the first number of which is about to be
issued ; it will be sent to all members. The dues of the society
are $2.00 per year ; life membership, $25.00.
7. Das Electrokardiogramm des gesunden und Kranken Men-
- schen ; von Prof. Dr. Frrmprica Kraus und Prof. Dr. Grore
248 Scientific Intelligence.
Nicotar Pp, xxii, 322. Leipzig, 1910 (Veit & Co.),—This
volume represents the first more elaborate attempt at a syste-
matic presentation of the scientific basis and latest technic of
the electrocardiographic method applied to the study of heart
functions in animals and man. The authors have particularly
emphasized the possibilities of the electrocardiogram as an aid
in clinical diagnosis, and have furnished a review of the rapidly
growing literature on the subject. Such pioneer work deserves
commendatory mention and will assist many physiologists and
clinicians in orienting themselves in the newer methods of
research. L. B. M.
8. Plane Trigonometry ; by Epwarv R. Rosstrys, Senior
Mathematical Master in the William Penn Charter School. Pp.
166. New York, 1910 (The American Book Company).—The
only valid excuse for an addition to the multitude of text-books
in ‘Trigonometry is that it be written by a teacher of Trigonome-
try in order to minimize his labor of teaching by giving to his
pupils his own methods in print instead of by dictation. Mr.
Robbins has in this way recorded the economies that he has
secured by 15 years’ experience. He seems to have systematized
the work in elementary plane Trigonometry a little better than
any of his predecessors, and thereby in so much diminished the
labor of thinking for his pupils. w. B.
9, Shop Problems in Mathematies ; by W. E. BRECKENRIDGE,
S. F. Mersereav, and ©. F, Moorn. Pp. 280. Boston (Ginn &
Co.).—This volume is designed for students in trade schools. It
discusses materials and machines for both wood and metal work,
and outlines construction work of various kinds. Mathematics,
including trigonometry, is also reviewed with particular refer-
ence to usefulness in shop practice. A large number of problems
drawn from practical work are given. D. A. K.
10. Ostwald’s Klassiker der Hxakten Wissenschaften. Leipzig,
1910 (Wilhelm Engelmann).—Recent volumes in this important
series are the following: Nr. 176. Mikroskopische Unter-
suchungen uber die Ubereinstimmung in der Struktur und dem
Wachstume der Tiere und Pflanzen, von Ta. Scuwann. Heraus-
gegeben von F. Htnsever. Pp. 242.
Nr. 177. Untersuchungen tiber Gegenstiinde der hdéheren
Geodisie ; von Cart Friepricu Gauss. Herausgegeben von J.
Friscuaur. Pp, 111.
Nr. 178. Physikalisch-chemische Abhandlungen; M. W.
Lomonossows, 1741-1752. Aus dem Lateinischen und Russischen
mit Anmerkungen herausgegeben von B. N. MenscnuTKin und
Max Sreter. Pp. 61.
OBITUARY.
Sir Francis Garon, the veteran English explorer and con-
tributor to many departments of science, died on January 17 at
the age of seventy-nine years. His most important writings were
those on Heredity, but his activities extended into a remarkable
number of different fields involving the application of quantita-
tive methods to science.
Dr. M. Wiruerm Meyer, the German astronomer, died two
months since, at Meran, at the age of fifty-eight years.
VOL. XXXL ? APRIL, 1911.
Established by BENJAMIN SILLIMAN in 1818.
THE
AMERICAN
JOURNAL OF SCIENCE.
Epitor: EDWARD S. DANA.
ASSOCIATE EDITORS
Proressors GEORGE L. GOODALE, JOHN TROWBRIDGE,
W. G. FARLOW ann WM. M. DAVIS, or Camsringe,
Proressors ADDISON E. VERRILL, HORACE L. WELLS,
L. V. PIRSSON anp H. E. GREGORY, or New Haven,
Proressork HENRY S. WILLIAMS, or Irwaca,
Prorressorn JOSEPH S. AMES, or Bautimore, Si
Mr. J. S. DILLER, or Wasuineron.
RUREAU GF
neem ant EF THNO! OGY
Ak Rail e] ; Vd he !
VOL. XXXI—[W HOLE NUMBER, CLXXXI.]
No. 184—APRIL, 1911.
“ansonian Ins P
/ os ity b
NEW HAVEN, CONNECTICUT. APR 29191] |
ore National Muse ;
a
‘J
THE TUTTLE, MOREHOUSE & TAYLOR O©O., PRINTERS, 123 TEMPLE STREET.
Published monthly, Six dollars per year, in advance. $6.40 to countries in the
Postal Union ; $6.25 to Canada. Remittances should be made either by money orders,
___—scregistered letters, or bank checks (preferably on New York banks).
as
Of Especial Interest to Mineralogists.
HIDDENITE FROM NORTH CAROLINA.
It has been some years since this rare gem mineral was procurable at the
mineral dealers; through very fortunate circumstances I procured a large
lot of these crystals at a remarkably low price; they range in size from 14
to 84 in. of very good color and quality. No doubt many collectors will be
glad to have the opportunity to procure a representative of this variety
of Spodumene, with a deep emerald green color; they range in price
from 50 cents to $2.00.
KUNZITE FROM CALIFORNIA.
I also received a large lot of Kunzite crystals, showing remarkable nat-
ural etchings; I am. now in a position to furnish a series of these etched
crystals which should be in every collection; they range in color from
white to deep lilac; former lots of this beautiful gem crystal were beyond ~
the average price for regular collectors; the present prices are far below
any material of this quality ever offered before; crystals range in size from
34 in. to 2144 in. long, from 75 cents to $5.00; will send a series of these
crystals for selection to anyone.
OTHER CALIFORNIA MINERALS.
Can safely state that my stock of California minerals is the largest in
the country, considering their quality; the following will suggest a few
of the additions to my present stock; Stibiotantalite, which is at present
extremely rare, both loose xls. and in matrix, prices ranging from $2.50-
$15.00.
Pink Beryl, good crystals, fair color, from $2.00-$12.00; Tourmalines,
all colors, loose and in matrix, from $2.00-$25.00. Awaruite, a new lot of
these interesting metallic pebbles, from the Smith River; their appearance
is something like Platinum nuggets; price from 25 cents to $1.50; from
the above locality I have also a fine lot of black and red Obsidian and
brown: polished from 214 in. to 344 inches, prices from $1.50-$2.00.
In addition to the above I also received quite a number of other minerals
too numerous to mention, from this state.
COLORADO.
Recent shipments have brought a large lot of Amazonstone, in groups
and loose crystals, single and twins, some of which are remarkable; also a
number of the celebrated Cripple Creek Tellurides, such as Tellurium,
Calaverite, Sylvanite, Gold Pseudo after Calaverite ; Calciovolborthite
crystallized, Carnotite, Amethystsin parallel growths, Topaz, Smoky
Quartz, Pyrites, Rhodochrosite quartz, with Fluorite and other well known
minerals at remarkably low figures.
I shall be pleased to send anyone on request an assortment, prepaid, for
selection, and guarantee satisfaction.
A. H. PETEREIT,
81—83 Fulton Street, New York City.
Phone Beekman 1856.
THE
AMERICAN JOURNAL OF SCIENCE
[FOURTH SERIES.]
Art. XXIV.—On the Ionization of Different Gases by the
Alpha Particles from Polonium and the Relatwe Amounts
of Energy Required to Produce an lon; by T. 8S. Taytor.
Introduction.
Iy previous papers,* the writer has shown that the air-equiv-
alents + of metal foils decrease with the speed of the alpha par-
ticles entering the foils. For sheets of different metals of
equal air-equivalents, the rates of decrease are approximately
proportional to the square roots of the respective atomic
weights. On the contrary, the air-equivalents of hydrogen
sheets increase while the hydrogen-equivalents of air sheets
decrease with the speed of the entering alpha particles, and at
such a rate as to be in agreement with the square-root law ob-
served for the decrease of the air-equivalents of the metal
sheets.
A comparison of the Bragg ionization curves, obtained in
atmospheres of air and hydrogen, when the pressure of the air ~
was so reduced that the range of the alpha particles from polo-
nium was the same in air as it was in hydrogen at atmospheric
pressure, showed differences which are sufficient to account for
the variations in the air-equivalents of the hydrogen sheets
with the speed of the alpha particles. These differences be-
tween the Bragg ionization curves in air and hydrogen sug-
gested that some such differences might be found between the
ionization curves obtained in other gases, and it was for the
purpose of making a detailed comparison of the ionization
* This Journal, vol. xxvi, pp. 169-179, Sept. 1908; ibid., vol. xxviii, pp.
307-372, Oct. 1909. Phil. Mag., vol. xviii, p. 604, Oct. 1909.
+ By air-equivalent is meant the amount by which the range of the alpha
particle is cut down by its passage through the foil.
Am. Jour. Sct.—FourtH SERIES, VoL, XXXI, No. 184.—Aprin, 1911.
18
250 Taylor--- Ionization of Different Gases by the
curves obtained in different gases that the present experiments
were begun.
Continuation of Experiments.
The apparatus used was the same as had been used in the
previous experiments.* The sheet iron case, enclosing the
apparatus proper, was replaced by a solid iron case which could
be readily exhausted. Polonium was used as the source of
rays and was placed in a brass cylinder of such dimensions
that the rays emerging from the cylinder fell well within the
limits of the ionization chamber for all available distances of
the source of rays from the ionization chamber.
In the determination of the ionization curve in any gas, the
vessel enclosing the apparatus was first evacuated and then the
gas admitted very slowly till the pressure it exerted was such
that the range of the alpha particles was exactly 1171 centi-
Fie. 1.
weer"
0 / e 3 4 5 6 7 8 9 Jo Ww
Fic. 1. The ordinates are the deflections in millimeters of the electrome-
ter needle per second. The abscissas are the distances in centimeters of the
polonium from the ionization chamber. Curves I, II, and III were obtained
when the maximum range of the alpha particle was exactly 11°1 centime-
ters in hydrogen, air, and methy] iodide, respectively.
meters, which was the maximum range available with the
apparatus. The Bragg ionization curve was then obtained in
the usual manner by observing the deflection of the needle of
the Dolezalek electrometer in scale divisions per second for
* Loc. cit.
Alpha Particles from Polonium. 251
various distances of the source of rays from the ionization
chamber. In this manner, the Bragg ionization curves were
obtained in the gases and vapors given in Table I. The curves
Fie. 2.
0 / % 3 4 5 6 7 8 9 10
Fic. 2. The ordinates are the deflections in millimeters of the electrome-
ter needle per second. The abscissas are the distances in centimeters of the
polonium from the ionization chamber. Curves I, II, and III were obtained
when the maximum range of the alpha particle was exactly 11:1 centimeters
in methane, ethyl chloride, and carbon disulphide, respectively.
in figures 1 and 2 and the dotted ones in figure 3 represent the
ionization curves obtained in the above manner in the gases
as indicated below the figures, respectively. The dotted por-
tion of each curve in figures 1 and 2 is assumed to be the form
it would take were it possible to move the polonium entirely
up to the ionization chamber. At any rate, such assumed por-
tions of the curves can differ but little from the actual curves.
It is to be noted, that the ionization curves shown in figures 1
and 2 are plotted differently from the regular Bragg ioni-
zation curve in that the values of ionization are taken as ordi-
nates and distances of the source of rays from the chamber as
abscissas, instead of vice versa as is usually done.
Although the curves in figures 1,2, and 3 represent some
differences from one another in regard to the relative amounts
of ionization for corresponding distances of the source of rays
from the ionization chamber, all of them are of the same general
form. From a re-determination of the velocity of the alpha
particle at different points in its path, and the assumption that
252 Taylor—Ionization of Different Gases by the
the ionization produced at any point in the path of the particle
is proportional to the energy consumed, Geiger * has shown that
the ionization Z at any point in the path is given by the rela-
tion
ee ae
(r—a) 4%
where ¢c and 7 are constants and « is the distance from the
source of rays. By comparing this theoretical ionization
eurve with the experimental curve obtained in hydrogen for a
pencil of rays, Geiger found the two to agree very closely:
This theoretical curve has been compared with the experi-
mental curves obtained in each of the gases and vapors given
in Table I and a very close agreement between theoretical
and experimental curves was found for each gas. To make
this comparison, it was necessary to determine the constants 7
and ¢ for each gas. For the value of 7, Geiger used the aver-
age range of the alpha particles in the pencil of rays. Since
the maximum range of the alpha particles in the cone of rays
used in the present experiments was always 11'1 centimeters,
the average range of the alpha particles in this cone of rays
emerging from the cylinder containing the polonium was
slightly less than 11:1 centimeters. Consequently 10°8 centi-
meters were taken as the value of the average range of the
alpha particle, that is, 10-8 centimeters are supposed to repre-
sent the average distance the alpha particles traveled in each
gas before losing their power of producing ions. In order to
determine c for any one gas, the ionization (ordinate of the
ionization curve figures 1, 2, and 3) and the corresponding dis-
tance x of the source of rays from the ionization chamber
(abscissa of curve) were substituted in the equation
zal c
~ (10°8—2x) 4
and the equation solved for c. Separate values of ¢ were thus
obtained for various distances of the source of rays from the
ionization chamber between «—0O and 9°5 centimeters, and
the mean value of these separate determinations found for
each gas. The mean values of ¢ as found in the above man-
ner for all the gases and vapors used are recorded in column
2, Table I.
* Proc. Royal Society, Series A, vol. Ixxxili, No. A 565, p. 505.
Alpha Particles from Polonium.
Fie. 3.
4
r¢)
(0) / 2 3 4 5
Gly Meera tin Se, hy Ot
Fie. 3. The full line curves I, II, and III are the theoretical ionization
curves for nitrogen, sulphur dioxide, and ether, respectively, as obtained by
substituting the corresponding values of ¢ given in column 2, Table I, in
the equation
= as “ where r = 10°8.
r—x
The dotted curves I, II, and III are the experimental ionization curves for
nitrogen, sulphur dioxide, and ether, respectively, and are plotted similarly
to the curves in figures 1 and 2
The full line curves, I, II, and III in figure 3 represent the
theoretical curves for nitrogen, sulphur dioxide, and ether,
respectively, as obtained by using the values of ¢ as recorded
in column 2, Table I, for the respective gases. The dotted
curves are the corresponding experimental curves and, as can
be seen, agree very well with the theoretical curves. The
agreement “petween the theoretical and the experimental
eurves for the other gases was equally as good as it was for
those given in fioure 3. In some cases the agreement was
much closer. This agreement between theoretical and experi-
mental curves confirms the assumption that the energy
assumed is proportional to the ionization produced
The ionization at any point of the path of the particle being
given by the relation
G
a (r—a) % ‘
253
254 Taylor—TLonization of Different Gases by the
the total area under this theoretical curve is a measure of the
total ionization produced by the alpha particle in the gas. If
A, represents the area under the theoretical curve, then
A ye dx = ve ea
(r—a)4
0)
ro)
= 3/2 c(r)% = 7°33 ¢
(7 being equal to 10°8 centimeters). Hence c is 3/22 of the
area under the theoretical curve when the average range of
TABLE JI, ic
¢ der expe. anetee Relative
Gaston or area under) rimental under ex-|2atio of the total ioni-) energy re-
Vapor theoretical | curve as perimen- zation in the gasto | quired to
eurve divid- measured | al METS that in air. produce an
ed by 7°33. jwith plan- fray ion.
| imeter. | ; Taylor. Bragg.
Air 11:24 980 | 87 ms on 1:00
ic 10°00 966 9€ 0:99 1-00 101
CH,I 14°73 1301 88 1°38 1°33 0°75
CH, 12°65 1156 91 118 0°85
C,H,Cl 14:05 1251 |) 89 1°29 1°32 0-77
CS, 15°60 B50) Me Sa 1°38 1:37 0°78
Air 14°64 1249 85 Pe: ae 1°00
N, 1381) 1) 0206 87 0:96 0:96 1-04
CO, 15°01 1262 84 1-01 1:08 0°99
O, 16°72 | 1415 | 85 1:13 1:09 0°88
C,H,,0 19-42 | 1702 88 1°36 1°33 0-74
Air SO 82 89 ae ac 1:00
so, 15°30 1223 80 1'03 aa 0:97
HCl 17°70 1530 86 1:29 ae 0:77
HBr 18732 po a 27 83 1:29 ae 0-77
Air 13°36 | 1190 89 Ae, aS 1:00
HI 17°68 | 1535 87 1°29 Se 0-77
the alpha particle is 10°8 centimeters in any gas whatever.
The values of ¢ recorded in column 2 of Table I are then 3/22
of the area under the theoretical ionization curves in the
respective gases.
The areas under the ionization curves being proportional to
the energies consumed in the production of ions in the respec-
tive gases, the value of ¢ in any one gas depends upon the total
ionization produced in the gas, and consequently upon the
energy required to produce an ion in the gas. Then the ratio
of the area under the experimental curve to ¢ should be a
constant. By dividing the areas under the experimental
Alpha Particles from Poloniwm. 255
curves as measured with a planimeter and recorded in column
3, Table I, by the values of ¢ for the corresponding gases,
the values recorded in column 4 were obtained and, as can be
seen, are approximately constant.
The areas under the ionization curves being the measures of
the relative ionizations produced in the gases, the ratios of the
total ionization produced in the gases to that produced in air
were determined by finding the ratio under each curve to the
area under the corresponding comparison air curve. After
the determination of the ionization curve in each gas, the ioni-
zation curve was always obtained in air to be used as a basis of
comparison. The ratios of the ionizations produced in the
different gases to that produced in air are recorded in column
5 of Table I. Bragg,* by a less direct process, determined the
ratio of the total ionizations in gases to that in air and his values
are recorded in column 6. There is a fairly good agreement
between the values as found by Bragg and those found by a
_ more direct process of measurement of the area enclosed by
the axes of references and the ionization curve for each gas.
Since the energy of the alpha particle is entirely consumed
before it ceases to produce ions, the energy required to pro-
duce an ion in any given substance will vary inversely as the
ratio of the total ionization in the substance to the total ioniza-
tion in air if the energy required to produce an ion in air is
always taken as the basis of comparison. The values of col-
umn 5 of the table are the ratios of the total ionizations pro-
duced in the gases as compared with the total ionization
produced in air. Consequently the reciprocals of these ratios
are the relative amounts of energy required to produce an ion
in the substance as compared with the energy required to pro-
duce anion in air. The values recorded in column 7 are these
reciprocals of the values in column 5, and hence are the rela-
tive amounts of energy required to produce an ion in the gases
as compared with that required to produce an ion in air.
These values indicate a considerable variation of the energy
required to produce an ion. The heavier and more complex
molecules are apparently more readily ionized than the lighter
and less complex ones. This is probably due to the electrons
in the heavier and more complex molecules being in a less
stable arrangement than they are in the lighter and less com-
plex molecules and hence more readily drawn out.
In conclusion, I wish to express my thanks to Professor
Bumstead for his valuable suggestions in connection with the
work and for loaning me the apparatus. I am also indebted
to Professor Boltwood for furnishing me the preparation of
polonium.
* Bragg, Phil. Mag., vol. xiii, pp. 8383-357, March, 1907.
256 Taylor—Ionization of Gases by the Alpha Particles.
Results.
1. The ionization curve obtained in various gases and
vapors with polonium as the source of rays is of the general
form
e
(72)
where J is the ionization; ¢ is a constant for any one gas
depending upon the total ionization produced, and conse-
quently upon the energy required to produce an ion in the
given gas; 7 is the average range of the alpha particles in the
cone of rays ; and z is the distance from the source of rays.
2. The agreement between the theoretical and the experi-
mental curves confirms the assumption made in previous papers
by the writer* and by Geiger,t that the ionization produced by
the alpha particle is proportional to the energy consumed.
3. The values of the ratio of the total ionization produced
by the alpha particle in different gases to the total ionization
produced in air as found by Bragg have been confirmed by a
more direct process.
4. The energy of the alpha particle consumed in the pro-
duction of an ion depends upon the nature of the molecule
ionized. It apparently requires less energy to produce an ion
in the gases or vapors which have heavy or relatively complex
molecules than it does in those gases of lighter or less complex
molecules.
i= y%
Laboratory of Physics, University of Illinois,
Urbana, Illinois, January 28, 1911.
* Loe cit. + Loe cit.
Duane— Heat Generated by Radio-active Substances. 257
Art. XXV.—On the Heat Generated by Radio-active Sub-
stances ; by Witt1am Duane.
Since the discovery of radio-activity questions relating to
the source and the transformations of the energy involved in
the processes have been considered of prime importance.
Early in the history of the subject Curie and Laborde* dis-
covered that radium generates heat continually, and also that
the heat effect increases as the emanation accumulates. A
little later Rutherford and Barnest found that the emanation
and the first few products of radium that form its induced
activity produce their shares of heat, and more recently still
Pegram and Webb¢ have succeeded in detecting a small heat
effect in a large mass (about four kilograms) of thorium oxide.
The ordinary methods of measuring heat (an ice calorimeter
for instance) are sufficiently sensitive to detect and measure
the heat generated by the quantities of radium, its emanation
and its induced activity now at our disposal. I have made
recently a number of experiments on the heat effects of other
radio-active substances, and in these I have had to use special
methods. At first I employed a modification of the differen-
tial air calorimeter devised by Rutherford and Barnes (1. ¢.),
but this was not sensitive enough and I then constructed a
new instrument which is considerably more sensitive than the
differential air calorimeter. The method is based on the rapid
increase in the vapor tension of a very volatile liquid when
the temperature rises. A and A’ (fig. 1) represent two glass
vessels, which are joined by the capillary tube B. The vessels
are half filled with the volatile liquid, and almost all the air
is pumped out by means of a water aspirator through the tube
C, which is then sealed off. A small bubble formed out of
the residual air left in the vessels is inserted in the tube B,
and the displacement of this bubble is observed by means of
a reading telescope or by projection with a lamp, lens and
seale. I usually employ the latter method, and the displace-
ment of the image on the scale is about eight times that of the
bubble in the tube.
It is not difficult to place a bubble of any desired length
in the tube B. It is sufficient to turn the apparatus upside
down, and let the liquid run out of the tube. Then
on replacing the apparatus right side up one finds the
tube more or less completely filled with air. The bubble is
* Comptes rendus, cxxxvi, p. 673, 1903.
+ Nature, Oct. 29, 1903; Phil. Mag., Feb., 1904.
tScience, 1904; Le Radium, 1908.
258 Duane—Heat Generated by Radio-active Substances.
usually much too long, and to reduce its length all that is
necessary is to tilt the apparatus up a little so as to cause a
current of the liquid to pass through the tube. This current
pushes the bubble down into the portion of tube below and at
the side, which is larger than the capillary portion. The
bubble remains in this portion of the tube, and the current of
the liquid passing it carries along the air little by little, thus
reducing the bubble’s volume. On repeating this process, |
Fie. 1.
SN
Se
causing the current to flow first in one direction and then in
the other, one can reduce the bubble to any desired length.
After the bubble has been replaced in the tube, and the
apparatus has been prepared for the experiment, the bubble
remains in the horizontal part of the tube. It never descends
into the large portion, no matter how much the temperature
of the room may vary: but it slowly disappears. The air in
the bubble dissolves in the liquid more or less rapidly accord-
ing to the nature of the liquid, the pressure of the air and the
dimensions of the apparatus. In my experiments it is neces-
sary to renew the bubble once in two or three weeks: and this
is a process requiring about five minutes time.
The form and dimensions of the capillary tube B have been
carefully studied. The length of the horizontal part is 44™
Duane—Heat Generated by Radio-active Substances. 259
and the internal diameter is a little more than -5"™. The
internal diameter of the two large parts is about 8™", and the
yertical parts joining the horizontal with the larger parts
should not have a larger diameter than the horizontal capillary
part. It is easier to control the movement of the bubble,
while placing it in the tube and reducing its size, if the capil-
lary tube is not joined to the ends of the larger parts, but to
the tops as indicated in the figure.
The volume of each vessel is about 50°.
The interior of the vessels and of the tube must be cleaned
most carefully. The least dirt or grease stops the bubble, and
in the experiments it is well to choose the part of the tube
where the bubble moves most freely.
If a source generating heat is introduced into the tube D,
the vapor tension is increased and the liquid pushes the bub-
ble toward the vessel A’. The instrument is very sensitive.
In my experiment I found that 1:5 10-* gram-calorie of
heat displaced the image of the bubble 1™ on the scale.
This sensitiveness is due to the rapid increase of the vapor
tension with the temperature. Among the liquids I have
tried, ether seems to be the best. Ether cleans and wets the
surface of the glass well, it has very little viscosity and its
vapor tension increases rapidly with the temperature, about
17™™ of mercury per degree centigrade at ordinary tempera-
tures. Ethel chloride works well also but is much less easily
manipulated.
The sensitiveness of the instrument varies a great deal with
the quantity of air in the vessels. If there is very little air the
displacement of the liquid does not change the pressure of the
gas much (saturated vapor tensions depending only on the tem-
perature), and an increase of pressure in A due to a slight pro-
duction of heat is opposed only by a change of level of the liquid
in A and A’. As ether is a light liquid, this change of level
opposes only a slight force to the displacement of the bubble.
For great sensitiveness, therefore, one must remove almost all
the air from the vessels, leaving only enough to form the
bubble. The sensitiveness depends also upon the ratio of the
eross-section of the capillary tube to the surface of the liquid
in the vessels. A decrease in the cross-section increases the
sensitiveness. I have found, however, that (if the liquid is
ether) a tube of less than °5™™ internal diameter does not work
well on account of the capillary forces.
Further, the displacement of the image of the bubble is
increased by the lens (or reading telescope). It is not desir-
able, however, to multiply the displacement more than eight
or ten times, as the loss in sharpness of image counterbalances
the advantage of increased displacement.
260 Duane—Heat Generated by Radio-active Substances.
In actual practice the protection of the instrument against
outside thermal disturbances is just as important as great sen-
sitiveness. In my earlier experiments Damibedden the two
vessels in a block, E (fig. 1), of lead (weighing 25 kilograms).
The vessels were held in place by a layer of paraffine, which
filled the space between them and the lead at the bottom. At
the top this space was filled with cotton wool. Two metal
rods, F (normal to the plane of the figure) support the block
of lead inside a brass box, G. These rods serve as axles
about which the lead can be turned, and thus the bubble of
air shifted to any desired position in the capillary tube. The
box G was completely enveloped in cotton wool contained in
a second box of zine (not represented in the figure). This
system of good conducting metal screens separated by spaces
filled with non-conducting material furnished excellent pro-
tection against thermal disturbances, but was not sufficient
where the greatest sensitiveness was required. The whole
apparatus, therefore, was placed in an electrical thermostat
similar to the one described some years ago in this Journal.*
In my later experiments I have replaced the cotton wool
with eider down, and I have added two large blocks of lead
on top of the box G. These blocks equalize the variations of
temperature coming from above. They are placed one beside
the other, leaving just enough space between them for the
tubes by which the substances to be examined are lowered into
the calorimeter. With these modifications I have found it
unnecessary to set the thermostat going, except on those days
when the temperature of the room undergoes wide fluctuations.
Very often the heat due to the radio-active processes is pro-
duced in relatively large masses of matter. In these cases it
is necessary to leave the substance to be examined for a long
time in the upper part of the tube by which it enters the calor-
imeter, in order to be sure that its temperature is as nearly
equal to that of the calorimeter as possible. This part of the
tube should lie between the two large blocks of lead, and
should be of metal to facilitate the equalization of temperatures.
If the generation of heat by the source is relatively large,
an appreciable quantity of it may be conducted down the
column of air into the calorimeter. In order to avoid this a
small quantity of eider down fastened to the end of a very
fine glass rod may be inserted into the tube just above the
calorimeter. In making an experiment the eider down is
removed, the substance to be examined lowered into the
calorimeter and the eider down quickly replaced.
Any one of several methods may be used in measuring the
heat generated by the source. On lowering the source into
the calorimeter one can wait until a sort of thermal equilib-
* Duane and Lory, this Journal, 1900.
Duane—Heat Generated by Radio-active Substances. 261
rium is reached, when the heat conducted away from the
calorimeter equals that given it per second by the source, and
observe the maximum displacement of the bubble of air. This
method works well provided the instrument is not arranged
for very great sensitiveness.
If, however, the apparatus is very sensitive it is better to
take the velocity of the bubble as a measure of the heat
generated per second. Although the instrument is well pro-
tected against thermal disturbances from the outside, yet the
bubble does not stay in the same place. The zero of the
instrument is not fixed. Nevertheless, if the apparatus has
remained undisturbed for a long time, and the temperature
throughout has become as nearly equalized as possible, the
natural drift of the bubble is slow and regular, and the change
in its velocity due to the heat from the source, when it is
lowered into the calorimeter, can be measured with consider-
able precision.
A third method is to compensate the effect of the heat
generated in the tube D by generating a known quantity of
heat in the corresponding tube D’ (figure 1).
The best method, however, is to compensate the heat effect
by absorbing the heat in the tube D itself as fast as it is
generated. This can be done by means of a current of
electricity flowing across the junction of two metals. Peltier
discovered that if the current passes in one direction heat is
generated, and if in the opposite direction heat is absorbed at
the junction.
In my earlier experiments I inserted a thermo-couple P of
iron and nickel wires into the tube D, and I determined the
current that absorbed the heat as fast as it was generated, by
varying the strength of the current until the velocity of the
bubble was the same as its natural drift. In the later experi-
ments I have replaced the simple thermo-couple by a metal
tube. The walls of the tube are 1™™ thick, and its external
diameter is just enough less than the diameter of the tube D
to allow of its being inserted easily into the latter. The length
of the metal tube is about 4°, so that the entire tube lies
inside the calorimeter. Half of the tube is of iron and the
other half of nickel, the two surfaces between the two metals
being vertical and parallel to the axis of the tube. An iron
wire is soldered to the outer edge of the iron half of the tube
and a nickel wire to that of the nickel half, so that a current
of electricity descending by the iron wire into the iron half of
the tube can pass across the joints into the nickel half and
ascend by the nickel wire. With this arrangement, when a
source of heat is lowered into the middle of the iron-nickel
tube, it is surrounded by a good conductor of heat, and the
distribution and compensation of the heat takes place easily
262 Duane—Heat Generated by Radio-active Substances.
and quickly. Thus the thermal equilibrium of the apparatus
is not disturbed much by the heat generated by the source.
This method is capable of considerable precision and can
be used, without changing the apparatus, to measure heat
effects varying from ‘001 gram-calorie to 2 gram-calories per
hour. Larger heat effects could be measured by increasing
the thickness of the iron-nickel tube and iron and nickel wires
so as to decrease their electrical resistance and the heat gen-
erated in them according to Joule’s law.
The iron-nickel tube has been carefully standardized by
inserting a small coil of manganine wire of known resistance
into the tube, by heating this with a known electric current,
and by determining the current in the tube that would exactly
absorb the heat produced.
The electric currents were produced by small storage
batteries, and their intensities were varied by changing the
resistances in plug resistance boxes contained in the circuits.
The resistances in these boxes, as well as the other resistances
in the cirenits, were carefully measured by a standard Wheat-
stone’s bridge. The electric currents were measured by com-
paring the electromotive forces of the storage cells with that
of a standard Weston cell by the potentiometer method, and by
dividing these electromotive forces by the total resistance in
the circuits.
The following table contains the data obtained in standard-
izing the iron-nickel tube. The resistance of the small coil
inserted into the calorimeter was 9°20 ohms, and that of the
lead wires attached to it was negligible. The electromotive
force of the standard Weston cell was 1,018 volts, and that
of the two cells forming the storage battery 4,153 volts.
TABLE 1.
Total resistance Heat produced Current iniron- Heat absorbed
in heating cir- in heating cir- nickel tube. per hour per
cuit. cuit calories . Ampere ampere
Ohms per hour —_—_-
Observed Corrected
480 "593 0716 0716 § 29
550 ‘450 *0540 °0542 8°30
650 "324 “0392 "0393 8°25
910 165 “0200 0197 8°37
The compensations were not always exact, and a small cor-
rection was made in the values of the current in the iron-
nickel tube. This correction was determined by observing
the velocity of the bubble of air.
The heat effect in the iron-nickel tube is due to two causes.
Firstly, the heat generated or absorbed at the junctions of the
metals according to the direction of the current (Peltier effect),
and, secondly, the heat generated according to Joule’s law,
Duane— Heat Generated by Radio-active Substances. 268
which is proportional to the square of the current and to the
resistance. ‘The fifth column in the table contains the heat
absorbed per hour and per ampere by the tube, and it appears
that this quantity is independent of the current in the tube.
This means that the absorption of heat is proportional to the
intensity of the cooling current, i. e., the resistance of the tube
is so small that the heat generated according to Joule’s law is
inappreciable, if the cooling is no larger than -6 calorie per
hour.
The mean value of the heat absorbed (or generated) per
hour and per ampere in the iron-nickel tube is 83 gram-
calories. I found 8-2 calories for the couple used in the earlier
experiments.
It is interesting to note that the electromotive force in the
Fig. 2.
Centimeters
Minutes
surface between the iron and the nickel must be about -00055
volt to produce this effect.
In order to determine the sensitiveness of the instrument I
sent a very small current through the iron-nickel tube, and
observed the change in the velocity of the bubble due to the
heat absorbed or generated. The curves in figure 2 represent
the displacements of the image of the bubble. The lines ad
and ed represent the bubble’s natural drift. The abscissas of
the points 6 are the instants at which the electric current
commenced to flow through the tube, and the abscissas of the
points ¢ are those at which the current was broken. For the
first curve the direction of the current was such as to generate
heat, and for the second to absorb it. It appears that the dis-
placement of the bubble due to the current was about the same
in the two cases but in opposite directions. This confirms
Peltier’s law, and indicates that the Joule effect is negligible.
264 Duane—Heat Generated by Radio-active Substances.
The strength of the electric current was ‘00019 ampere, and
the heat generated or absorbed *0016 calorie per hour. In ten
minutes ‘00027 calorie was generated or absorbed and _ this
quantity of heat displaced the image of the bubble about
1-6". It follows that one millimeter displacement of the
image corresponds with :00017 calorie of heat absorbed or
generated.
In some other experiments I have found that the displace-
ment of the bubble is proportional to the quantity of heat
absorbed or generated, provzded that the absorption or genera-
tion is not too rapid.
These results are used in estimating the small correction that
must be applied, if the value of the current that exactly
absorbs the heat generated by a source has been determined
only approximately.
Centimeters
Minutes
I have measured the heat generated by radiothorium and by
polonium. These experiments were described in two notes
presented to the Paris Academy of Sciences on June 1 and
June 21, 1909.
Since the first experiments I have measured the heat gen-
erated by the polonium several times to see if the heat effect
decreased with the time according to the law of decay of
polonium. Half a given quantity of polonium disappears in
about 142 days.
The curves in figure 3 represent the displacement of the
bubble in these experiments, the dates being for curve 1 the
4th of May; for curve 2 the 4th of June, and for curve 3 the
25th of June. In each case the lines ab and fg represent
the natural drift of the bubble. The abscissas of the points 6
are the instants at which the polonium was lowered into the
Duane—Heat Generated by Radio-active Substances. 265
calorimeter, and the abscissas of the points / are the instants at
which the polonium was raised again. The numbers written
near the lines cd and de are the electric currents in amperes
which were flowing through the iron-nickel thermo-couple dur-
ing the corresponding intervals of time.
Between the points ) and eI was searching for the proper
value of the current to counterbalance the heat effect, and
between the points e and 7 I was reducing the current to zero.
The last experiment was not as good as the others, because the
natural drift of the bubble was large and changed a little dur-
ing the experiment.
I compared the ionization due to the polonium when spread
out in a thin layer on a disk of platinum (4 ¢) with that due to
a thin layer of radium. The results of the experiments appear
in Table 2.
TABLE 2.
Heat
Weight of effect
RaBr~ that of this
Date of Current that Heat pro- Ionization hassame quantity
experiment compensated duced cal- current due activityas of radium
1909 heat effect. orie per topolonium polonium calorie
Ampere hour g. per hour
May 4 00143 012 Mes} Se Or" 75 °0110
June 4 “00110 ‘009 119+ 107 66 0095
June 25 ‘00100 008 "99 X10)" “Bil 0084
It is evident that the generation of heat and the ionization
current due to the polonium decrease with the time. The
ionization current decreases at a rate indicating decay to half
value in 136 days, which is very close to the value previously
found by other experimenters. The heat effect decays a trifle
faster than this, but the differences are not greater than one
would expect considering the magnitude of the quantities of
heat evolved. It follows from this that the heat effect was
certainly due to the polonium. .
On account of the difficulty of obtaining saturation in
measuring the ionization of the radium and of the polonium,
the method of comparing the activities of the two substances
must be regarded as approximate only. Remembering this.
it appears that the heat generated by the polonium is ver
close to that generated by the quantity of radium that would
produce the same ionization as the polonium.
I have made «a number of experiments on phosphorescent
salts to see if they generate heat when in the phosphorescent
state. Every time I examined such a salt one or two hours
after it had been withdrawn from the light of the sun (or of an
ultra-violet ray are lamp), I found a small but measurable
generation of heat. Twenty-four hours later not the slightest
effect could be detected in the majority of cases, but a few
times I observed a small generation of heat and on withdraw-
Am. JOUR. Poteau Series, Vou. XX XI, No. 184.—Apnrin, 1911.
ell
266 Duane—LHeat Generated by Radio-active Substances.
ing the salt from the calorimeter found that the phosphorescent
light had disappeared. It is impossible to affirm, therefore,
that the heat effect is directly related to the emission of vzscble
phosphorescent light. It may be due to the emission of visi-
ble and invisible rays together, or it may be caused by some
reaction of a secondary nature.
These researches, however, have suggested to me the follow-
ing question: if a quantity of radium is mixed with a phos-
phorescent salt, causing it to phosphoresce brilliantly, does the
mixture generate the same quantity of heat as the radium
would generate alone? There appear to be three possibilities :
(a) the ener gy of the rays is absorbed (at least in part) in pro-
ducing chemical reactions in the phosphorescent salt. In this
case the heat effect of the mixture should be less than that of
the radium alone, at least at first. (0) the radium rays acting
on the atoms and molecules of the salt liberate a part of their
chemical or subatomic energy. In this case the heat produced
by the mixture should be larger than that produced by the
radium alone. (¢) the energy of the radium rays is rapidly
transformed (in part) into the energy of the phosphorescent
light without producing other reactions, and in this case, if all
the light is absorbed in the vessel containing the mixture, the
heat produced should be the same as that due to the radium
alone.
In order to investigate this question I made the following
experiments. On December 3d, 1909, a certain quantity of
a salt containing finely pulverized radium chloride and barium
chloride was divided into two parts. One part, A, weighed
"0314 gram and was sealed into a small glass tube. The other
part, B, weighing :0206 gram, was thoroughly mixed with
‘267 gram of phosphorescent zine sulphide, and then sealed in
a second glass tube similar to the first.
Several times during the five weeks following the sealing
of the tubes I measured the heat effects of each of them, and
I also compared the intensity of the y-radiation emitted by
them with that due to a standard tube containing 26°5 grams
of radium chloride. The following table (3) contains the
results of these experiments :
TABLE 3.
Date of Quantity of RaCl-? Production of Ratio
of that produces the heat calories A
experiment same y-rays per hour Tay
= a => = Si =>
A B A B
December 7 1°66 1:07 Be is pir 1°55
December 7 se: deen sales 2 +098 5S
December 21 DAVY 1°57 nae eM tinh 153
December 21 ere eee 199 129 1:54
January 5-- 2°39 1°56 oe Be 1°53
January 6.. Bese sits = 201 “2 1°58
Duane—Heat Generated by Radio-active Substances. 267
The y-radiation and the generation of heat increased
between the 7th and the 21st of December, but after that no
increase was perceptible. This was due to the accumulation
of the emanation and the induced activity, which after three
weeks attained approximately their saturation values.
The sixth column contains the ratios between the tubes A
and B. It appears that these ratios are the same no matter
what the date of the experiment was and no matter whether
the y-rays or the heat effect was measured. It follows that
the presence of the phosphorescent salt does not appreciably
change the rate of generation of heat by the radium.
The following facts may be noticed in passing: The phos-
phorescence of the mixture has become less imtense than at
first but is still brilliant. The hght has also changed its color,
becoming more orange.
In order to investigate the heat effect in the case where the
phosphorescence is produced by the 8 and ¥ rays in willemite
and in platinum-barium cyanide, I arranged the following
experiment: A long, fine tube is inserted into tube B of the
calorimeter and around the end of this tube is packed the
phosphorescent salt. A very small glass capsule hermetically
sealed containing radium can be lowered down the fine tube
to the center of the salt. The walls of the tube and capsule
are so thin that under these conditions the salt phosphoresces
brilliantly.
I compared twice the y-rays from the capsule with those
from the standard and found that the quantity of radium in
the capsule corresponded with 1:91 and 1:92 mg. of RaOl,.
The heat effects observed on lowering the radium to the
center of the phosphorescent salt were the following :
TABLE 4,
Heat
calorie
Salt used per hour
67 gr Platinum-barium cyanide -_-------- 170
DONG) Ore Aan Nieves 5 5 ey oes ee wee ca Nie
No phosphorescent salt -_....--.--- Styl
No phosphorescent salt _--- .-- ee MAlG
It is evident that the generation of heat is the same whether
the phosphorescent salt is present or not. It follows from
these two series of experiments that there is no appreciable
absorption of energy in producing chemical reactions, and that
the rays do not liberate an appreciable amount of chemical
_ subatomic energy.
These results are interesting from the point of view of
the amount of energy necessary to effect the organs of sight.
268 Dwane—Heat Generated by Radio-active Substances.
In the first series of experiments the phosphorescence was
produced for the most part by the a-rays of the radium. We
know that each a-particle that strikes the phosphorescent zine
sulphide produces enough light to affect the eye, and it follows
from the experiments described above that the energy of this
light is no larger than the energy of the a-particle. The smallest
velocity of an a-particle that has been measured and at the
same time detected by its scintillation is 510° —— , and the
kinetic energy of the a-particle at this velocity is 8107 erg.
. ; : 6 1 : .
This energy is about that required to raise G0 of a mille-
1 : sas
gram 3559 of a millimeter. The energy necessary to pro-
duce the sensation of sight is less than the above quantity,
since only a part of the total light energy enters the eye, and
since probably the whole energy of the a-particle is not trans-
formed into luminous energy.
The heat generated by one gram of pure radium can be
calculated from the data of Table 3. It is for tube A 110 and
for tube B 108 calories per hour. The difference between these
two numbers is not greater than the errors of experiment.
The heat effect of one gram of radium calculated from
the data of Table 4 is 117 calories per hour, a value considerably
larger than the preceding values. This difference cannot be
explained by errors of experiment. It is probably due to the -
fact that the radium employed in the second series of experi-
ments is several years older than that employed in the first
series, and contains, therefore, more of the disintegration
products of the radium, especially polonium, which generate
heat.
I have made a number of attempts to measure the heat pro-
duced by the rays from radium at a distance from their source.
In the first experiments a thermopile, a bolometer, and a
radiometer were tried, but none of these instruments gave
satisfactory results. A modified form of differential gas ther-
mometer gave positive indications of a heating effect, but the
only instrument that proved satisfactory was the differential
calorimeter described in the present paper. I hope shortly to
publish some details of these experiments, but will state here
simply that the problem is somewhat different from that
of measuring the energy of ordinary radiations (at least as
far as the penetrating radium rays is concerned), because a
relatively large amount of matter is required to stop these
penetrating rays, and the heat is generated throughout the
mass of this matter.
Pirsson and Rice—Geology of Tripyramid Mountain. 269
Arr. XX VI.— Contributions to the Geology of New Hamp-
shire, IV. Geology of Tripyramid Mountain; by L. V-
Prrsson and Wm. Norru Ricr.*
Introductory.—Tripyramid Mountain is in the southern
part of the White Mountains in New Hampshire. The point
formed by the intersection of 44° N. and 71° 30’ W. is about
two miles northwest of its northwest lower slope. It is entirely
within the township of Waterville and a little east of its cen-
ter. Surrounded by other mountains, Osceola, Kancamagus,
Passaconaway, Whiteface, Sandwich Dome and Tecumseh,
peaks which rise 3-6 miles distant, it is much concealed, and
there are not many places where it can be observed in its full
proportions from below. ‘The retired character of its situation
is much enhanced by the wild and heavily wooded nature of
the region in which it stands, the only habitations in the upper
valley of Mad River, which drains the township, being a sum-
mer resort hotel and a few scattered farm houses. The east-
ern slopes of the mountain are drained by headwater branches
of Swift River, whose upper basin is a similarly wild and
heavily for ested region. Consequently its summit is not easily
accessible and is little visited by tourists, especially as the view
is largely circumscribed by the neighboring peaks and obscured
by the thick growth of spruce serub covering it. The best
point to reach it from is the hotel at Waterville, which is 12
miles from the railway at Campton. A walk of about four
miles, partly on trails through the forest and partly a scramble
up rough and overgrown mountain brook beds, brings one to
the lower slopes and the slides described beyond.
Topography.—Tripyramid Mountain is a roughly oval mass
which rises about 2000 feet above the floors of the valleys
about it. It is crested by three peaks with saddles between,
called the North, Mid, and South Pyramids, to which it owes
its name. Its appearance from the west is seen in the
accompanying view, which we owe to the kindness of Mr.
A. L. Goodrich. It was taken looking across the mead-
ows above the old lumber dam at a place on Slide Brook
called Swazeytown, below the junction with it of Cascade
Brook.
On the north the mountain is connected with the peaks of
Kancamagus by a high ridge with an intervening point upon
*Some years since one of us (L. V. P.) went to Waterville, N. H., to see
the occurrence of the ‘‘ossipite”” mentioned in this paper and to collect
material. While engaged in this hefound W.N. R. had also studied the Tri-
pyramid rocks in the field. We joined forces and the present paper is the
result. It is proposed to follow this with one dealing with the petrology of
the rocks.
270 = Pirsson and Rice— Geology of Tripyramid Mountain.
it, sometimes called Fourth Pyramid. On the south it
descends to a bench, or roughly level area, known as Flat
Mountain, whose elevation is about 2500 feet above sea level
and which in tur again descends into the valley of Cold
River. North Pyramid is about 4200 feet above the sea, the
other pyramids are a little lower. The mass, as thus defined,
is over two miles long, by about one and a half broad; the
Fie. 1.
Fie. 1. View of Tripyramid Mountain.
Looking east from above the Swazeytown Dam. The North Slide and
Ravine of Avalanches are seen to the left, the South Slide on the right.
distance between the North and South Pyramids about a mile
along the crest. The details of the topography are shown on
the accompanying map, which has been compiled from various
sources, the approximate expression of the topography of the
older map of the Hitchcock Geological State Survey being cor-
rected in details by later maps of parts of the area made by
the Yale School of Forestry under the direction of Mr. Henry
Gannett and Prof. Il. H. Chapman, by Mr. C. W. Blood, and
one of trails and stream courses by Mr. A. L. Goodrich, and to
Pirsson and Rice—Geology of Tripyramid Mountain. 271
these gentlemen we desire to express our indebtedness for the
use of this material. The western two-thirds of the map has
been made chiefly from these sources, the eastern third is from
the older state map. We have added a few corrections of our
own.
Nearly everywhere the mountain, and also for the most part
the surrounding area, are covered with a dense forest growth.
On the slopes of the mountain and on its top this is composed
of a thicket of small spruce trees which rise through a floor
mat composed of intermingled dead and fallen tree trunks,
more or Jess decayed, accumulations of spruce needles, shrubs
and moss, into which one often sinks to the waist, and through
which progress is extremely difficult. On the lower slopes the
kinds of vegetation are somewhat different but the character
of the thicket remains the same and the mantle is often
swampy in addition. Were it not for the slides and the chan-
nels of the streams running from them, the underlying rocks,
except on the summit, would be completely concealed by this
vegetable growth and deposit, which on a rainy day, to one
immersed in it, calls to mind Darwin’s description of Terra
del Fuego.
The Slides.—The most interesting features of the mountain
are what are locally known as the “slides.” These are two tre-
mendous landslides, or avalanches, which have occurred, one
on its north, the other on its south slope. The North Slide has
left a bare face of underlying rock extending from the narrow
Ravine of Avalanches, which separates the mountain from the
next peak to the north, upward for half a mile along the slope
and with over a thousand feet of elevation, with an average
angle to the horizontal of 30°. Starting at a point not far
below the summit, it gradually widens until at its base nearly
the whole north face of the mountain, up into the head of the
Ravine of Avalanches, is exposed. The naked rock surface left
by this, which is about as steep and smooth as one can comfort-
ably climb upon, is interrupted here and there by piles and
trains of rock débris and lines of small trees and shrubs grow-
ing in crevices. The most conspicuous lanes of rock face
exposed are separated from several minor similar ones east of
them on the north slope and these from each other, by long
strips of soil and forest. The exposed rock of these smaller
eastern lanes appears quite weathered. Minor slides have also
occurred from the opposite slope of the neighboring elevation
into the Ravine of Avalanches, which appears to be well named;
see fig 1. A view of the chief double lane of sliding of 1885
is seen in fig. 3, taken from the opposite mountain side by
Prof. E. L. Rice. Small drainages pass down these lanes and
empty into Avalanche Brook, which heads below.
“ay MOZMOT, “S@]IJ JO e[vog
779,
BS
=
oa
“o1qqey
eee
01449
NM eS +4,
=
<1
{=\—
Ag
any zy 7
D
Ve
Yer |e
ji
“AJLMIOLA puUv ULeyUNOW; pimerddiary, Fo
‘slaqaq pur
FMP TRIOLTH
“opTURIH)
2a od
eos
Hes
S|
sft
pai es
so
a= os
lon!
Oreos
Ge
Dn OF
sya}
S28
O58 °S
on S
SE°2
Seler
aS) =
a's
ac LY
—oetn 2
RE, St)
= FS
— oot
ee:
YH ee
ow R
nl
13 (aS
Be°
> Og
See
hy a=
ano
> cs 2
as EH
= iS)
A 8
As &
= Oo
aa
Pirsson and Rice—Geology of Tripyramid Mountain. 273
Fie. 3.
Fie. 3. View of the North Slide from the south slope of Fourth Pyramid.
274 = =Pirsson and Rice—Geology of Tripyramid Mountain.
small amount of débris spread down the ravine below, com-
pared with the extent of surface denuded.
The condition which has caused the slides appears to be the
steep and smooth rock surfaces on which the accumulating lay-
ers of largely organic deposits rested. When these became
heavy enough, at a time when they were saturated with water
after long and torrential rains, which also lubricated the under-
lying rock surface, they broke away and slid down. The steep-
ness and smoothness of the bed rock is occasioned by a certain
sheeting which it possesses and which is discussed later. Judg-
ing from the conditions, and from what has occurred, it seems
possible that other slides may occur in the future. The South
Slide is in essential respects, as to size, height, ete., quite com-
parable to the North one, only in this case the thickness of
the débris of soil, rocks, ete., which moved, was apparently
greater. Thus the underlying rock i is exposed only at the upper
part of the slide, the earth mantles the middle part and
increases in thickness as one descends, while the glen below in
which the Slide Brook heads is choked with the accumulated
material that moved down into it. This lower part has the
hummocky surface characteristic of landslides and is furrowed
by shallow ravines which the drainage has cut into it. Many
large blocks of rock, some of them 8-10 feet long, are exposed
in these ravines ; most of them are of syenite from the mountain
above, but others are of black trap, porphyritic granite, dark
gabbro, ete., and are evidently transported glacial erratics. This
avalanche occurred on Oct. 4th, 1869, and a second one on
Aug. 18th, 1885, as a sequence to the terrible downpour which
also caused the largest North Slide. It can be just seen in
fig. 1 to the right as a white line showing through the dark
forest. An admirable account of these slides and the causes
which produced them has been given by Mr. A. A. Butler.*
Listory.—The first mention of the geology of Tripyramid
Mountain that we have been able to tind is in a description
of the South Slide by Prof. G. H. Perkins+ written shortly
after its occurrence. The mountain is called by him Passa-
conaway ; there appears at that time to have been some. con-
fusion in regard to the use of this name, and later it became
fixed to the mountain east of Tripyr amid, which now bears it.
In his description of the slide he states that the upper part of
the mountain is composed of a gray syenite. As this term
was then used it bore reference to the fact that the rock
contained hornblende, it did not mean that it was free from
quartz, or nearly so. The name, however, proves correct as
* Appalachia, vol. iv, No. 3, p. 177, 1886.
+ This Journal (2), vol. xlix, p. 158, 1870.
-7
Pirsson and Rice—Geology of Tripyramid Mountain. 275
used in the former, or in the later, petrographic sense, as will
be shown later. He speaks also of the presence of trap dikes
in it from an inch or two up to a foot in thickness. He does
not mention their color, so it is uncertain whether this refers to
aplitic or lamprophyrie dikes, or to both, but the use of the
word trap suggests the latter. He speaks also of extensive
layers of black hornblendic rock a mile below the slide on the
stream ; this evidently refers to the gabbro mentioned later.
The next account bearing on Tripyramid is found in Hitch-
cock’s Geology of New Hampshire.* In this, references to
the mountain, to its rocks and geology, are made in a number
of places, and in vol. II, p. 211 and following, a general de-
scription of its geology is given. As weshall have occasion in
s sy