The Chemical History of a Candle · Lecture I, part 1 · Part 1: Lecture I: A candle and its flame
1. What candles are made of
Goal: Your child can name the materials candles were made from in Faraday's day and explain the three things every candle has to provide.
You'll need
- Two or three different candles from around the house (unlit), with any labels
- A science notebook and pencil
- A plain candle (a short, thick one is best) and a few tea lights
- A large plate or metal baking tray to stand them on
- Matches or a long lighter (for the adult only)
- A glass of water nearby
What's in the book
The start of the first lecture. Faraday greets the "boys and girls," shows candle-wood from the Irish bogs, dips, miners' candles and a candle from a sunken ship, then explains how tallow, stearin, spermaceti, wax and paraffin candles are made, and why fancy fluted candles burn badly.
The lesson, step by step
Meet Faraday
Michael Faraday (1791–1867) started work as a bookbinder's apprentice and became one of the most famous scientists in Britain. He gave these six talks to young people at the Royal Institution in London over the Christmas holidays of 1860–61. The chemist William Crookes edited them into this book, so we read them almost word for word as Faraday spoke.
The Royal Institution still holds Christmas Lectures for young people every year.
SayFor the next weeks, one ordinary candle is going to teach us chemistry.
A starting list
Ask your child to write down everything they think happens when a candle burns. Where does the wax go? What is the flame? Keep this list. You will look at it again at the very end of the course.
Read together
Read pages 13 to 21 aloud, taking turns. Faraday's old spellings ("shew" for show, "honour") are fine to read as they are.
There is no better, there is no more open door by which you can enter into the study of natural philosophy, than by considering the physical phenomena of a candle.
"Natural philosophy" was the old name for science.
The idea in plain words
Faraday starts with a piece of wood from an Irish bog that burns like a candle. He says it has everything a candle needs:
The fuel provided, the means of bringing that fuel to the place of chemical action, the regular and gradual supply of air to that place of action — heat and light — all produced by a little piece of wood of this kind, forming, in fact, a natural candle.
So every candle needs three things: fuel, a way to bring the fuel up to the flame, and a steady supply of air. Watch for all three in every lesson.
Look at real candles
Lay your candles on the table, unlit. Read any labels: paraffin, beeswax, soy? Find the wick. Is the candle narrower at the top? Faraday says moulded candles are made as cones so that they slide out of the mould, but wax candles are made differently:
A wax candle can never be cast.
Now light one plain candle on its plate and just watch it quietly for two minutes. Don't explain anything yet; you will study it next time.
Safety: an adult lights the flame and stays right there; tie back long hair and roll up sleeves; set the candle on a plate on a fireproof surface, away from paper and curtains; keep a glass of water nearby.
Say it back
Your child tells back, in their own words, how Faraday says candles are made. Prompts:
What is a "dip," and how is it made?
What did the candle from the sunken ship show?
Why are fluted candles bad candles?
What we know now
Most candles today are made of paraffin wax that comes from petroleum. Faraday's paraffin came from Irish bogs. Spermaceti came from whales; whales are protected now, and no one makes candles from them.
Afterwards
Notice it this week: every time you see a candle, a lamp or a fire, ask "where is the fuel, how does it reach the flame, and where does the air come in?"
Tip
Faraday mentions people and places of his day (Mr. Field of Lambeth, the Royal George). There is no need to look them all up; keep the story moving.
Answers to the book's problems
The three things: fuel; a way of bringing the fuel to the flame; a steady supply of air. A dip is a length of cotton dipped again and again in melted tallow until enough tallow builds up. The Royal George candle had lain in salt water for many years and still burned regularly when lit. Fluted candles are bad because their uneven shape spoils the even cup of melted fuel (he explains this fully in the next part).
Worked out for this site from the scan. If a number in your copy differs, trust the book.