ROBERT C. PLUMB
chemical exemplified
Why Not Solve the Detergent Problem by Going Back to the Old Way-Soap? lllusfrafing principles o f solubilify and chemical separation techniques
Contribution by John J . Singer, Hampshire Chemical Division, W . R. Grace & Company Unlike modern detergents, the soaps which our grandparents used for washing clothes do not easily pass through soil and do not feed wells with polluted water from septic tanks. Soap deposits are biodegradable so that nature can clean up the pollution which man generates. One can, with good reason, ask, "Why don't we return to the technology of the good old days?" We could, if we would accept s t 8 clothes hardened by chemical deposits to the point where shirts will stand by themselves in the corner and if mother would give up her automatic washing machine and go back to feeding wet clothes through a wringer! Some very elementary chemistry underlies the problem. A soluble soap such as sodium palmitate will react with many metal ions in the dirt of soiled clothing, such as calcium, to produce insoluble soaps such as calcium palmitate. Of course if one washes with soap and hard water, the source of insoluble soap deposits is not limited to the soiled clothing but comes from the water as well; however, even washing clothes in distilled water with soap will not get rid of insoluble soap deposits-the soluble dirt in dirty clothes hardens the water. With detergents these insolubles are not formed; rather the detergents and dirt stay in solution and get rinsed away, unfortunately too far a t times, from your septic tank on to the neighbor's water well and out his faucet. The insoluble soap deposits produced by the reaction of soaps with metal ions will, as they accumulate in a fabric, make i t stiff; grandmother often had to ruffle clothes vigorously to break up the stiffness and make the clothes wearable. Using soap with the modem washmg machine would create an even greater fabric stiffening problem than people used to have when they washed with soap and squeezed the water out with wringers. I n an automatic washer the clothes act like filter paper in a filter-as the dirty water is pumped out and spun out, any insolubles are held back by the filter. The wringer method of extracting water leaves much less of the insolubles behmd in the clothes. It became practical to replace the wringer with a centrifugal water extractor only because modern detergents solubilize the dirt. It is interesting to note how the development of our technology is controlled by the laws and facts of chemistry. 330 / Journal o f Chemical Education
Chirality in Sea Shells lllustrafing stereoisomerism
Suggestion and information supplied by Professor Dean F. Martin, University of South Florida Persons who gather sea shells on ocean beaches have close a t hand a good and often overlooked example of stereoisomerism. Gastropoda, i.e., snails, have a shell that is spirally coiled and shows a striking chiral preference; that is, a preference for either right-handed or left-handed spirals. Ninety-nine percent of the species of gastropoda have a right-handed spiral; however, some species are different, for example the lightning whelk (a large gastropod of the Carolinas and Texas, growing up to 16 in. in size) is normally a left-handed spiral. Occasionally a typical right-handed species will produce a shell which is left handed. The Indian chank (of the Bay of Bengal) is one such example; the rare left-handed shells of this species have been highly valued and mounted in gold and placed on Hindu altars. The explanation of the handedness of shells (given in the August 1971issue of "Sea Secrets," an International Oceanographic Foundation publication) is The earliest gastropods had disk-like planispiral shells. However, torsion apparently originated due to one retractor muscle being asymmetrically placed, and this seems to have put some evolutionary pressure on the adult. The gastropods were left with a. single retractor muscle and this, of course, had to he attached to the mlnmella. Some left-handed snails are mirror images of right-handed forms while others, like Busycon perueram, are right-handed animals in a left-handed shell.
A complete chemical.explanation of this phenomenon has not yet been given. It would seem that the macroscopic chirality of an individual specimen must be explicable in terms of the chemistry of its hereditary factors and the preponderance of one stereoisomer in a molecule which controls its growth.
