Candles Part 3 - Natural Philosophy

Over the winter of 1860-1861, as the secession crisis was tearing the American Republic into pieces, Michael Faraday, one of the most renowned scientists of the day, delivered a series of six lectures on science at the Royal Institute to audiences consisting principally of children. The Royal Institute had offered such lectures during the Christmas holidays since 1825, and Mr. Faraday delivered 19 of the lectures series between 1829 and 1860.

Mr. Faraday’s lectures were accompanied by demonstrations that illustrated the phenomena he described. The 1860 lectures, published under the title The Chemical History of a Candle, did not deal with cutting edge discoveries but rather explained some of the basic knowledge about the makeup of the physical world that science had obtained and conveyed some of the wonders to be found in so commonplace an object as a candle.

Mr. Faraday was himself a wonder. Born to a family of limited means in 1791, he had a scant formal education and was apprenticed to a bookbinder, where he took the opportunity to read widely and gained an interest in science. Upon the completion of his apprenticeship in 1812, he attended a series of lectures on science given by Sir Humphry Davy, an eminent scientist of the day. Mr. Faraday sent Sir Humphry a handwritten book based upon the notes from his lectures, which was well-received. When an opening for a chemical assistant occurred at the Royal Institute, Sir Humphry hired Mr. Faraday, which opened to him a career of experimentation and analysis. In 1832 Oxford University awarded Mr. Faraday an honorary doctorate. Although Sir Humphry made a number of significant discoveries, it has been said that his most important contribution to science was Michael Faraday.

In the first lecture given in the 1860 series, Mr. Faraday showed that the heat of the flame melted the nearest portion of the candle and that the melted wax (spermaceti, stearin, tallow) was held in a little cup formed in the top of the candle.

You see, then, in the first instance, that a beautiful cup is formed. As the air comes to the candle, it moves upward by the force of the current which the heat of the candle produces, and it so cools all the sides of the wax, tallow, or fuel as to keep the edge much cooler than the part within; the part within melts by the flame that runs down the wick as far as it can go before it is extinguished, but the part on the outside does not melt.

If a current of air moved horizontally across the candle, a side of the cup would melt and the candle would gutter.

The liquid wax in the cup did not burn -- indeed, inverting the candle extinguished it because the candle could not make the wax hot enough to ignite it. The molten wax, however, moved up the wick through “capillary action”. Mr. Faraday demonstrated this by pouring colored water into a dish from which rode a column of salt -- the colored water could be seen rising through the salt. As the wax, rising through the wick approached the flame, it vaporized, and as a vapor, it ignited.

In the midst of his lecture, Mr. Faraday observed:

Now the greatest mistakes and faults with regard to candles, as in many other things, often bring with them instruction which we should not receive if they had not occurred. We come here to be philosophers, and I hope you will always remember that whenever a result happens, especially if it be new, you should say, “What is the cause? Why does it occur?” and you will, in the course of time, find out the reason.

The first lecture made further observations about the structure and brightness of the flame, and subsequent lectures dealt with the nature of combustion, the facts that water is a product of combustion in a candle’s flame, that hydrogen is a component of candles, that oxygen in the atmosphere is necessary for combustion and that carbon is also a component of candles, and they concluded with observations about respiration and an analogy of respiration to the burning of a candle.

Even in wartime, even in a country at war (which England was not in 1860), the life goes on with its commonplace obligations, its entertainments and, hopefully, its learning.