On Reading Napoleon’s Buttons

Posted by jns on 1 February 2008

Also a few months back, I read the delightful Napoleon’s Buttons : How 17 Molecules Changed History, by Penny Le Couteur and Jay Burreson (New York : Jeremy P. Tarcher/Putnam, 2003, 375 pages). I haven’t run across so many popular chemistry books so far, but this clearly is one of the good ones. I enjoyed the blend of historic anecdote, chemical analysis, introduction of technical vocabulary, and copious molecular diagrams. Yes! A popular-science book with molecular diagrams! At whatever level one reads the diagrams–even if one sees them only as decoration–they enhanced the text in my opinion.

My book note is here. Below is an extra extract on a subject that I find fascinating and unlikely: the discovery of saponification, that magical transformation of fat and ashes that creates some that cleans things! So, here we have some social history of bathing, chemical history of saponification and relsted topics, and some fun facts thrown in to blend the flavors.

(As an aside, this excerpt ends just at the idea of long molecules called “lipids” is introduced. It’s the physical chemistry of lipids that allows soap to wash away grease in water. How that all works and some of the collective properties of lipids doing their job was a hot topic among my fellow condensed-matter physicists in my early research days, although I never worked on it myself.)

In Europe the practice of bathing declined along with the roman Empire, although public baths still existed and were used in many towns until late in the Middle Ages. During the plague years, starting in the fourteenth century, city authorities began closing public baths, fearing that they contributed to the spread of the Black Death. By the sixteenth century bathing had become not only unfashionable but was even considered dangerous or sinful. Those who could afford it covered body odors with liberal applications of scents and perfumes. Few homes had baths. A once-a-year bath was the norm; the stench of unwashed bodies must have been dreadful. Soap, however, was still in demand during these centuries. The rich had their clothes and linens laundered. Soap was used to clean pots and pans, dishes and cutlery, floors and counters. Hands and possibly faces were washed with soap. It was washing the whole body that was frowned upon, particularly naked bathing.

Commercial soap making began in England in the fourteenth century. As in most northern European countries, soap was made mainly from cattle fat or tallow, whose fatty acid content is approximately 48 percent oleic acid. Human fat has about 46 percent oleic acid; these two fats contain some of the highest percentages of oleic acid in the animal world. by comparison, the fatty acids in butter are about 27 percent oleic acid and in whale blubber about 35 percent. In 1628, when Charles I ascended to the throne of England, soap making was an important industry. Desperate for a source of revenue–Parliament refused to approve his proposals for increased taxation–Charles sold monopoly rights to the production of soap. Other soap makers, incensed at the loss of their livelihood, threw their support behind Parliament. Thus it has been said that soap was one of the causes of the the English Civil War of 1642-1652, the execution of Charles I, and the establishment of the only republic in English history. This claim seems somewhat far-fetched, as the support of soap makers can hardly have been a crucial factor; disagreements on policies of taxation, religion, and foreign policy, the major issues between the king and Parliament, are more likely causes. In any event, the overthrow of the king was of little advantage to soap makers, since the Puritan regime that followed considered toiletries frivolous, and the Puritan leader, Oliver Cromwell, Lord Protector of England, imposed heavy taxes on soap.

Soap can, however, be considered responsible for the reduction in infant mortality in England that became evident in the later part of the nineteenth century. From the start of the Industrial Revolution in the late eighteenth century, people flocked to towns seeking work in factories. Slum housing conditions followed this rapid growth of the urban population. In rural communities, soap making was mainly a domestic craft; scraps of tallow and other fats saved from the butchering of farm animals cooked up with last night’s ashes would produce a coarse but affordable soap. City dwellers had no comparable source of fat. Beef tallow had to be purchased and was too valuable a food to be used to make soap. Wood ashes were also less obtainable. Coal was the fuel of the urban poor, and the small amounts of coal ash available were not a good source of the alkali needed to saponify fat. Even if the ingredients were on hand, the living quarters of many factory workers had, at best, only rudimentary kitchen facilities and little space or equipment for soap making. Thus soap was no longer made at home. It had to be purchased and was generally beyond the means of factory workers. Standards of hygiene, not hight to state with, fell even lower, and filthy living conditions contributed to a high infant death rate.

At the end of the eighteenth century, though, a French chemist, Nicolas Leblanc, discovered an efficient method of making soda ash from common salt. The reduced cost of this alkali, an increased availability of fat, and finally in 1853 the removal of all taxes on soap lowered the price so that widespread use was possible. The decline in infant mortality dating from about this time has been attributed to the simple but effective cleansing power of soap and water.

Soap molecules clean because one end of the molecule has a charge and dissolves in water, whereas the other end is not soluble in water but does dissolve in substances such as grease, oil, and fat. [pp. 286--288]