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Every student who studies atmospheric pressure in physics or chemistry learns the principles behind the construction of barometers. Cistern barometers, such as those found in most laboratories, consist of a long glass tube containing an inverted column of liquid having an open end in a cistern of the liquid. Students learn that the column of liquid is supported by air pressure and is equal in weight to a column of air of the same diameter.

Simple, reliable estimates of biosolids N availability are needed to develop land application programs that will benefit crops without risk of excess nitrate leaching. This study was conducted to assess the effect of biosolids processing on plant available nitrogen (PAN) release during the first and second growing seasons after application. We compared 14 sources of biosolids and a range of inorganic N rates in two replicated field experiments on established tall fescue (Festuca arundinacea Schreb.). The biosolids encompassed a range of treatment and dewatering/drying processes. A single biosolids application was made in May of the first year, and tail fescue yield and N uptake were measured by harvest for the next two growing seasons. Inorganic N was split across multiple applications each year. Fertilizer efficiency regression equations were developed for the inorganic N treatments, and used to calculate biosolids PAN from N uptake data. Year 1 PAN was similar across a range of biosolids treatment processes. For nonlagoon biosolids, PAN averaged 37 [+ or -] 5% of total biosolids N. Lagoon biosolids PAN ranged from 8 to 25% of total N, with the oldest, most stable biosolids having the lowest PAN. Year 2 PAN averaged 13 [+ or -] 2% for nonlagoon biosolids, excluding heat-dried materials, which were lower (5 to 8%). Our calculations indicated that about half of the Year 2 PAN became available during the cool season, suggesting that winter cover cropping may be needed to reduce the potential for nitrate leaching loss in summer annual cropping systems.

Issues are presented concerning the effectiveness of the Solvita Test, the use of Carbon Dioxide Detection Tubes and the Self Heating Test as measures which can be used to determine the maturity of compost.

Sulfur hexafluoride is a very dense, inert gas that can be used in several fascinating chemistry classroom demonstrations. It is primarily used in industry to insulate electric switches since the gas decomposes slowly when in contact with a high voltage electric spark. The gas is an arc suppressant and measuring the distance sparks jump in sulfur hexafluoride and air is a good experiment. Measuring a gas-filled balloon over time is another good experiment because air diffuses into the balloon causing it to expand. Other experiments are mentioned using the nontoxic gas.

Universities can use poster contests to recruit chemistry students. These contests can help students become more aware of the opportunities in chemistry. Public relations and printing departments can help finance the contests. Universities should establish rules for the contests in such areas as the theme, the size of the posters and the number of colors used. The University of Nebraska offers prizes of $25 to $50, but the prestige of winning seems to be more important to students.

Chemistry teachers can use liquid nitrogen to produce liquid oxygen that supports combustion. The liquid oxygen is generated by partially filling a metal container with liquid nitrogen. The liquid that collects on the outside of the container is liquid oxygen. A balloon and a cigarette can be used to demonstrate such scientific principles as Charles' Law, the properties of liquid oxygen and partial combustion.

Some chemistry teachers require students to memorize certain concepts simply because they believe that a competent chemist should be knowledgeable about those concepts. One theory holds that people should make their own cloth, despite the invention of machinery, simply because their ancestors made their own cloth. This theory can be applied to chemistry education. Teachers should not require students to memorize trivial information for no apparent reason. Repetition and memorization stifle educational development.