1. Bei der modischen Oxydation von metallischem Silber in alkalischer Lösung entsteht zunächst quantitstiv und umkehrbar das Oxyd Ag2O.

The Monte Carlo method of computer simulation is a powerful tool for studying physical systems. With this method, random numbers are used to simulate processes that occur randomly in nature (Gould and Tobochnik, 1988). Monte Carlo methods are used in such diverse research areas as physics and materials science, economics, medicine, biochemistry, communications, and other fields. Computer simulation permits one to ascertain the quality of models for processes; it is flexible and allows precise control of various variables, facilitating the study of multicomponent systems, parallel and interrelated phenomena, or long-term variation processes (Binder, 1986). There are multiple advantages to using simulation: it can save time, labor, and money, compared with traditional laboratory experiments, while eliminating the safety hazards that may be encountered when conducting experiments (Hammersley and Handscomb, 1964). Many phenomena in horticulture take place at random; one of them is the container medium that constitutes the skeleton of the rhizosphere.Packings of spheres serve as models for many physical systems (Barker and Grimson, 1990;Dallavalle, 1948;Finney, 1983) and are achieved by establishing particle coordinates that represent a real assembly of particles constituting a structured system from which several properties can be calculated (Finney, 1983).A container medium can be considered a random system of particles. Applying simulation techniques to container medium systems is contingent on simultaneously characterizing their packing patterns and establishing analogies between container media and geometrical particles. This approach has long been considered useful in studying soil properties (Slichter, 1899).New materials that might be useful in container medium formulation are becoming avail-

Nitrapyrin at 50 ppm, increased dry weights of tomato (Lycopersicon esculentum Mill.) and total N when pine bark comprised part of the medium and NH4 was part of the N treatment. If the medium consisted only of pine bark, nitrapyrin increased dry weights and total plant N with NO3–N and/or NH4–N treatments. The NO3–N level in the medium was higher with all N treatments when nitrapyrin was incorporated. The increase in plant growth is directly related to the higher NO3–N levels in each medium where nitrapyrin was incorporated. The higher media NO3–N with nitrapyrin are attributed to inhibition of the nitrification process and a subsequent inhibitory effect on NO3–N loss.

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Component and particle-size effects on shrinkage of two-component potting media were determined. Milled pine bark-sand mixtures were used to determine particle-size effects on shrinkage. Shrinkage curves formed an inverted V with maximum shrinkage at the 1:1 (v/v) ratio. No shrinkage occurred when bark was mixed with bark or sand with sand. Shrinkage increased linearly in the range of 0% to 50% bark and decreased linearly in the range of 50% to 100% bark. Each half of the shrinkage curve was a mirror image of the other half. Shrinkage curves for peat-sand and peat-perlite were similar in form to that of bark-sand media.