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AAAS is now offering reprints of selected articlesfrom recent issues of Science.

The following reprints are now available fromAAAS Reprints, 1515 Massachusetts Ave., NW,Washington, D.C. 20005.

CopiesOrdered

B. Berelson, "Beyond Family Planning" (7 Feb.1969), 12 pages

W. W. Cooley and R. Glaser, "The Computer andIndividualized Instruction" (31 Oct. 1969), 12 pages

C. Djerassi, "Prognosis for the Development ofNew Chemical Birth-Control Agents" (24 Oct. 1969),8 pages

James D. Carroll, "Science and the City: The Ques-tion of Authority" (28 Feb. 1969), 12 pages

C. A. Doxiadis, "Man's Movement and His City"(1 8 Oct. 1968), 8 pages

Heinz F. Eichenwald and Peggy C. Fry, "Nutritionand Learning" (14 Feb. 1969), 8 pages

Marshall J. Gilula and David N. Daniels, "Violenceand Man's Struggle to Adapt" (25 April 1969),12 pages

Garrett Hardin, "The Tragedy of the Commons"(13 Dec. 1968), 8 pages

B. L. Crowe, "The Tragedy of the CommonsRevisited" (28 Nov. 1969), 8 pages

J. Platt, "What We Must Do" (28 Nov. 1969),8 pages

Richard Evans Schultes, "Hallucinogens of PlantOrigin" (17 Jan. 1969), 12 pages

P. Suppes and M. Morningstar, "Computer-AssistedInstruction" (17 Oct. 1969), 12 pages

Andrew T. Weil, Norman Zinberg, and Judith M.Nelsen, "Clinical and Psychological Effects of Mari-huana in Man" (13 Dec. 1968), 12 pages

Reprints of other articles published since 1 Septem-ber 1968 can be made available in quantities of 25or more for classroom use. Identify each article byauthor, title, page number, and issue date.

Prices and TermsOne reprint-$1.00

10reprints

4 pages $4.008 pages $5.00

12 pages $5.50

Two to nine reprints-600 each

25reprints

$ 8.00$11.00$13.00

50reprints

$15.00$20.00$25.00

100reprints

$25.00$35.00$45.00

Please enclose payment with order. Do not sendcurrency.

13 MARCH 1970

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year's meeting recevied partial supportfrom The Population Council as wellas from various commercial sources.It was organized, as before, by H. P.Klinger. Approximately 50 people at-tended. The participants thank Pro-fessor G. Stalder, medical director ofChildren's Hospital, who served as host,and the City Council of Basel for hos-pitality. There are no printed proceed-ings.

SALOME GLUECKSOHN-WAELSCHDepartment of Genetics,Albert Einsteinz College of Medicine,New York 10061

Calorimetry

Calorimetric techniques and theirapplications were discussed at the 24thCalorimetry Conference, held at theWentworth-by-the-Sea near Portsmouth,New Hampshire, 14-16 October 1969.The Huffman Memorial Lecture is

a feature of the conference and ispresented by a man selected on thebasis of excellence in thermochemistryand thermodynamics. In 1969 the ad-dress was given by Ward N. Hubbard(Argonne National Laboratory), leaderof a group engaged in fluorine com-bustion calorimetry. Hubbard summa-rized the heat of formation data ob-tained for some 30 fluorides by directcombustion of the elements in fluorine;he discussed the periodicity of derivedbond energies when plotted againstatomic number of the central atom.The plot also served to indicate whereadditional data are needed.

Reports were made on measurementsof specific heat at low temperatures andtheir interpretation in terms of phe-nomena such as phase transformationsin alloys and organic compounds, mag-netic ordering in ferrous molybdateand tungstate, antiferromagnetism ofDyPO4, and molecular motion in clath-rates and polymers. The effect of iso-lated heavy impurity atoms in a lighthost lattice was discussed at the 1967Conference; measurements have nowbeen extended to higher temperaturesand higher concentrations to test theo-retical explanations. Papers on the spe-cific heat of liquid helium providedtests of theoretical predictions of theinteraction potential between He" atomsand critical point behavior of He4.Difficulties in measuring the heat ca-pacity of plutonium carbide due toself-heating were described.A continuing concern of thermo-

chemists is the accuracy of experi-mental methods; several papers offereddata affording cross-checks by differentapproaches. The rotating bomb methodfor heat of combustion of organicchlorine and bromine compounds waschecked against solution thermochem-istry by means of the hydrochlorideand hydrobromide of trishydroxyamino-methane (THAM) at the Thermo-chemical Center, Lund, Sweden; re-sults were in good agreement. Theenthalpy of neutralization of THAMwith aqueous HCl has been proposedas a standard exothermic reaction forsolution calorimetry; a series of re-searches at several locations was re-ported by S. R. Gunn which related thisquantity to the long-established heat ofcombustion of benzoic acid. A directmeasurement of the enthalpy of neutral-ization at the National Bureau of Stand-ards is not in agreement to the desireddegree; further work is apparentlyneeded. A new determination was madeat Argonne National Laboratory ofthe enthalpy of formation of aqueousHF by means of the enthalpy of reac-tion of fluorine and hydrogen to formliquid HF combined with the enthalpyof solution of liquid HF in water.The result did not agree within experi-mental error with recent data by otherapproaches; a selected value satis-factory to all is not yet established.New data on a Calorimetry Confer-ence specific heat standard, Al.203,were reported from the National Bu-reau of Standards.New equipment which was described

included data acquisition systems forlow-temperature specific heat calorim-eters, a solution calorimeter, a liquidnitrogen boil-off calorimeter, and solu-tion, titration, and mixing calorimeters.A high precision water bath (Tronac,Inc., Orem, Utah) achieves a long-termstability of 0.0003°C. A microcalorim-eter developed at the University ofColorado was applied to the studyof the myoglobiin oxygen reaction withimpressively precise results. A designfor miniature platinum resistance ther-mometers for low-temperature calorim-etry was approved and a manufactureris now being sought to produce suchthermometers commercially.

Information about the 25th Calorim-etry Conference may be obtained fromE. D. West, National Bureau of Stand-ards, Boulder, Colorado.

G. C. SINKETlherm16al Resear-ch Laboratory,Dowv Chlemlical Comiipanzy,Mlidland, Michiigan 48640

SCIENCE, VOL. 1671526

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