No abstract

Many laboratory manuals include lengthy schemes for extraction of caffeine from tea.1 A time-saving experiment using No-I)oz tablets as the source has recently been described in this Journal.2 However, soft drinks derived from the kola bean, and some that are not, also contain caffeine that can be isolated and purified in as little as 1 hr.In some of the soft drinks that we studied, simple extraction with chlorinated solvents yielded caffeine that was contaminated by relatively large amounts of benzoic acid. Showing a strong pl\ dependence (caffeine does not: Ka < 10-14; Kb < 10-14), benzoic acid can easily be held in the aqueous phase, but it. may be extracted and isolated as a second product. In such beverages as Coca-Cola, Pepsi Cola, Royal Crown Cola, Dr. Pepper, Mountain Dew, Orchard Park Cola (a local brand), and the low-sugar and sugar-free versions of several of these, we found that a 12-oz.can contained 25-50 mg of caffeine. Half a can is therefore sufficient for students either to see the crude product, to

Reversible interconversions between the cluster anions [HRu3(CO)11]- and [H3Ru4(CO)12]- on fully hydroxylated magnesia in the presence of H2 or CO at a pressure of 1 atm have been observed that mimic interconversions of these ions in basic solution. In the presence of H2, the [HRu3(CO)11]- anion on fully hydroxylated magnesia is converted to [H3Ru4(CO)12]-, which in turn transforms back to [HRu3(CO)11]- when H2 is removed and CO is added. The organometallic species on the fully hydroxylated magnesia surface are mobile at room temperature, and the interconversion steps are reversible and can be repeated. Possible reaction pathways are proposed.

A Simple Titrimetric Determination of Lead in Gasoline "Getting the lead out" has become almost a household expression today. In spite of the availability of unleaded gasolines, leaded fuels are still prevalent; the rate of decline in leaded gasolines appears to be much less than had been anticipated.In a previous publication in this Journal, the problem of pollution from lead compounds emitted in automobile exhaust was discussed and the lead content of various brands of gasoline as determined by X-ray fluorimetry was reported.-An instrumental method utilizing atomic absorption spectrophotometry has also been published.3 Besides these instru-1 Author to whom correspondence should be addressed.-Bills, J.

Illustrates some areas of uncertainty in the current literature regarding the mechanism of digestion and presents an experiment that is more consistent with current biochemical research.