Study of buried seed banks (viable seeds deposited in the soil near parent plants) provides a relatively easy way of determining cumulative effects on seed production and species' altitudinal limits. Sites, methods, validity, interpretation, problems of collection on a mountain, and germination techniques are discussed. (Author/DH)

Describes a computer program that students use to check their suggestions of possible lines of investigation during a microbiology exercise, the results of procedures, and the decisions made on the basis of experimental evidence. Effectiveness of the program and practical aspects of the investigation are considered. (DH)

Measurement of the brightness of moonlight by comparison with lamp-light from a low wattage light bulb is an elementary project in astronomy which illustrates scientific principles for the freshman level. Two methods used for the comparison (shadow brightness method and grease spot method) are explained, with suggestions and expected answers. (DH)

Background information, materials needed, and procedures used are provided for potentiometric fluoride, halide, orthophosphate, and sulfate titrations. Typical results obtained are also provided for each type of titration. (JN)

Background information, procedures used, and typical results obtained are provided for a simple homogeneous precipitation preparation of chromium(II) acetate. (JN)

Discusses direct chemical information that can be obtained from modern nuclear magnetic resonance (NMR) methods, concentrating on the types of problems that can be solved. Shows how selected methods provide information about polymers, bipolymers, biochemistry, small organic molecules, inorganic compounds, and compounds oriented in a magnetic…

The design and use of an inexpensive thermistor thermometer is described. In addition to providing a rugged thermometer, using the instruments offers an opportunity to have students become familiar with new principles and techniques, such as principles of thermistors, the Wheatstone bridge, and the concept of calibration. (JN)

Describes an experiment that involves the extraction of lead from gasoline into an aqueous solvent using iodine monochloride reagent. This method (which avoids the aspiration of organic solvents) also illustrates the use of wavelengths other than the most sensitive wavelength and effects of flame stoichiometry and burner height upon absorbance.…

Background information, experimental procedures used, and typical results obtained are provided for an experiment that demonstrates the stereospecific arrangement of cyclopropyl halides to allylic halides. (JN)

Describes the use of phase transfer conditions to prepare a sulfur and phosphorus ylide. Background information and procedures are provided for the experiment (which can be completed in one three-hour laboratory period). (JN)

Presented are procedures used to assay the activity of lipase during storage at three different temperatures. Since lipase solutions can decay even when refrigerated, it is recommended that the enzyme be freshly prepared prior to laboratory sessions in which they are used. (JN)

Provides procedures to measure the calcium concentration in fruit juice by atomic absorption. Fruit juice is used because: (1) it is an important consumer product; (2) large samples are available; and (3) calcium exists in fruit juice at concentrations that do not require excessive dilution or preconcentration prior to measurement. (JN)

Although it is a major synthetic reaction, the Wittig reaction has not been used in undergraduate laboratories due to the potential hazard and difficulty associated with the preparation/use of the strong bases needed to generate the required ylides. Procedures are presented for an experiment in which these difficulties are avoided. (JN)

Describes an experiment which shows: (1) how measurements of the reaction electromotive force for the cell (Pt/glass/NaCl(aq,m),buffer/AgCl/Ag/Pt) can be utilized in determining the absolute pH of the buffer; and (2) the demonstration of the use of the Debye-Huckel model of an electrolyte solution in solving an important electrochemical problem.…

Describes an experiment in which undergraduate students can do simple Huckel Molecular Orbital (HMO) calculations from spectral data for a series of four closely related dyes. (JN)