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JOURNAL OP CHEMCAL EDUCATION
Decsmsn, 1929
LIVING CHEMICALS HOWARD JAMBS,' UNIVHRSITY OP COLORADO, BOULDER, COLOUDO Chemical experimentation is, in itself, a very useful and instructive, as well as entertaining, hobby. The science of chemistry acquires an entirely new aspect when it is backed by experimentation. I do not refer to the cut and dried experiments given in many first courses in chemistry. I refer to experiments which, for various obvious reasons, cannot be given in the regular class work, but which are, nevertheless, sensible and do exemplify some definite chemical principle. Experiments of this kind are interesting-all the more so when original-and will stand repetition. Unique experiments can be readily found if one will but look for them. Magazines and books of a chemical nature will usually yield a supply. The experiments may not be given in the regular form, but an enterprising experimenter can fashion information into experiments. A single subject, provided i t has scope and simplicity, will keep the experimenter busy a t his hobby for some time. One subject, which was responsible for much of my early interest in chemistry, provided me with material for experimentation for several months. This subject is the formation of the so-called chemical plants. Crystals of metallic salts, thrown into a solution of sodium silicate, "grow" into beautiful plants. A solution of one part water glass and three parts water constitutes a good mother soluJion. Solid crystals of cobalt chloride, manganese sulfate, ferric chloride, and several other salts produce plants of various shapes and colors. The prin&ple behind the growing process is simple. As soon as the salt crystal enters the solution, it begins to dissolve. As rapidly as this occurs, an insoluble, jelly-like precipitate is formed by the union of the metal ions with the silicate ions. This action occurs in a space only slightly larger than the crystal. Consequently, a long ribbon or ribbon-like structure results. After I had used every salt I could obtain that would possibly form a plant with the silicate solution, I turned to other mother liquids. The most successful of these was a 10% solution of potassium ferrocyanide which, with cobalt nitrate crystals, produced an olive-green stalk having many branches. That result was surprising, and I have not yet completely satisfied myself as to why the main stalk should branch. Ferrous sulfate and nickel nitrate, however, also gave branching stalks, while cupric chloride (freshly prepared) gave a single ribbon. If the experimenter has access to a good microscope, the above subject broadens considerably. The procedure here, however, is just the reverse of the above. For example, place a little powdered ferrous chloride on the glass slide, and moisten the chemical with a drop of water-glass solu' Winner of five-dollar award in contest closing October 15th.
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tion. The salt will swell up into a tiny ball, which will quickly send forth its growths. Based on the results of such experiments (excluding those with the microscope) I have made a number of chemical gardens for friends. Florence flasks which had their necks broken were salvaged from waste jars for containers. When the top parts of these are ground off by striking wire gauze gently across the glass, they make excellent containers. Some colored pebbles improve the general appearance, and a layer of oil on top of the mother liquid prevents evaporation.
