Chemical garden

Thomas Mann beautifully combines sensory observation and fantasy in his description of a chemical garden in the book Doctor Faustns which he wrote in his old age ... 

On completion of the experiment the complete chemical garden is treated with dilute milk of lime, the pH being kept below 8. The mixture is then centrifuged (or simply decanted), separated from the precipitated mixture and the filtrate diluted and poured down the drain. The residue is placed in the plastic con-laiiier used lor collecting less toxic inorganic waste. 

A chemical garden. Vegetation created by a combination of inorganic salts... 

Containers for food products, cosmetics, household chemicals Garden hoses, lawn furniture Floor coverings, wallpaper House siding, gutters, window frames Pipes fittings Film sheeting... 

Steinbock reminds us that polymeric materials need not be organic. In Chapter 11, he examines self-organization in the silica garden system. This fun system is a common demonstration and actually dates back to the seventeenth century. In the conventional chemical garden experiment, small salt particles or crystals are seeded into aqueous solutions containing anions such as silicate, carbonate, borate, or phosphate. Such experiments are uncontrolled and caimot be made continuous. Steinbock explains how they replaced the salt crystals by a continuous flow of salt solution. He details the variety of instabiHties that can occur and how bubbles can be used as templates for tube growth. 

Balkose, D., Ozkan, F., Kokturk, U., Ulutan, S., Ulku, S., and Nlsll, G. (2002) Characterization of hollow chemical garden fibers from metal salts and water glass. J. Sol-Gel Sci. Technol., 23, 253-263. 

Thouvenel-Romans, S. and Steinbock, O. (2003) Oscillatory growth of silica tubes in chemical gardens./.Am. Chem. Soc., 125, 4338-4341. 

Cartwright JHE, Garcf-Ruiz JM, Novella ML, Otalora F (2002) Formation of chemical gardens. J CoUoid Interface Sci 256 351—359... 

Some substances are odorous, others are not. Humans can smell at a distance if one smells the roses in a garden, it is not ordinarUy considered that part of the rose is in contact with the nose. Substances of different chemical constitution may have similar odors. Substances of similar constitution usuaUy have similar odors, eg, in a homologous series nevertheless, even stereoisomers may have different odors. Substances of high molecular weight are usuaUy inodorous and often nonvolatile and insoluble. The quaUty as weU as the strength of odor may change on dUution. 

The fluidised bed coating technique is used extensively for wirework items such as dish drainer racks, vegetable racks, office trays etc. The technique is also widely used for street furniture e.g. metal lampposts, signposts and balustrading, and for metal office furniture and domestic garden furniture. It also provides chemical corrosion resistance on valves, pipes, couplings etc. 

G. J. Janz, G. Gardener, U. Krebs, andR. P. T. Tomkins, J. Phys. Chem. Ref Data i (1974) 115 Molten Salts, Vol. 4, Part 1 Fluorides Eleetrieal Conduetance, Density, viseosity and Surfaee Tension Data, American Chemical Society-American Institute of Physics-National Bureau of Standards, Washington, DC, 1974. 

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