Skip to content

Want to save money on soaps and detergents?

Have you ever watched Fight Club?
Remember how Brad Pitt stole human fat to make soap?
And how he gave Edward Norton a chemical burn with lye? And then poured vinegar on him to neutralize the base?
Yeah, don’t do that.
Anyhow, I did watch that movie a few months ago, and since I’m usually up for the challenge of making my own anything, I thought it would be interesting to make my own soaps from scratch.
It’s not a difficult process, and the materials needed are not expensive at all, but it takes several days to make the soap. The quantities in the recipes are far too much for my personal use, and even too much for me to give as gifts, but investing all that time/money/effort/space/equipment for a smaller amount seems pointless when regular soap isn’t really that expensive.
Like Schrödinger’s cat and the principle of uncertainty, when you save money, you spend time and vice versa (bad joke, forget I said anything).
BUT, yesterday I saw this article, on how to save money on your laundry detergent, and that brought back my interest in the subject.

OK, let’s start at the beginning

What are detergents and soaps?
These are molecules with a dual nature- part hydrophilic and part hydrophobic. When in water, they dissolve only partially, and the hydrophobic part of the molecule clumps together to form a tiny oil bubble, which can solubilize other oily substances within it. When in oil, they do the opposite- the hydrophilic part of the molecule clumps up to form tiny bubbles and trap other water soluble molecules within it. The exact behavior of each detergent or soap depends on the balance between its hydrophobic and hydrophilic parts (HLB, hydrophilic lipophylic balance), the nature of the head group (hydrophilic part) and the nature of the tail group (hydrophobic part), but the general behavior is to form clumps or layers out of one part on the molecule, while the other part is soluble in its surroundings.
The difference between soaps and detergents is that soaps are ‘natural’ and detergents are completely synthetic. The reason it matters whether something is ‘natural’ or completely synthetic, is because it has a different impact on the environment and our health.
Soap would be composed of a naturally occurring fatty acid, such as is found in the membrane of cells and fatty tissues (that’s the fat Brad Pitt stole), and has an aliphatic tail (a hydrocarbon chain) and a carboxylic acid for a head:

The carboxylic acid is hydrophilic, because it is polar, similar to the water, and it can also form hydrogen bonds with the water. Unfortunately, that is not hydrophilic enough for the molecule to be soluble in water, because of its long tail. What you need is to force the head to be more polar, or have more hydrogen bonds with the water.
To make the head more polar, you can turn it into an ionic group, by changing the pH for example. The carboxylic group is an acid, and at a certain pH it will lose its hydrogen from the hydroxyl group and become negatively charged. In order to do that, we usually use lye (NaOH), a very strong base:

That’s the main component of bar soap.
But this head group is very sensitive to pH, hard water (containing a high concentration of Ca+2, Mg+2), and a high concentration of electrolytes in general. In their presence it will return to its acidic form and lose its function.
The larger the head group, the more hydrophilic it is, the less sensitive it is to its environment. So a better soap would be one made with KOH:

That’s the main component of liquid soap.

The next step to a less sensitive substance and a larger hydrophilic head would be to replace the carboxylic acid entirely with something much more polar or more strongly ionic. That would make it a detergent, because the process of forming such a molecule is synthetic.
An ionic detergent may have a sulfate (SO4-3) head or a sulfonate (SO3-2) head. The difference is the ester bond versus the ether bond of the head to the tail:

(sodium lauryl sulfate, SLS, SDS, or sodium dodecyl sulfate, is a detergent and an emulsifier used in toothpaste, shampoo and other things. I think I’ll give toothpaste its own post)
The ester bond is sensitive to pH, and so is sensitive to the presence of water, whereas the non-ester bond is not. That’s why sulfate detergents are usually solids, and sulfonate detergents are usually liquids. The liquid detergents are less sensitive, more efficient, and you need less of them to clean whatever it is they are designed to clean.

To add more hydrogen bonds to the head, you can react the carboxylic acid with ethylene oxide, in a chain reaction, which will produce non-ionic detergents:

This is a chain reaction which cannot be controlled, and the end result is a mixture of molecules with different lengths and different behaviors. You can direct the reaction toward a certain average length depending on the initial starting concentration of the reactants, but you will still get a mixture, not a pure substance. These materials are usually toxic if swallowed.
These detergents are more stable and more efficient then the previous ones, but you can see that again we have an ester group, which is sensitive to pH. To make the detergent even more stable, we need an ether bond.
The ether bond cannot be produced by the carboxylic acid, so instead of a fatty acid, we need to start with a fatty alcohol:

Now we have one of the better detergents, which is very stable, easily soluble in water, you need only a small amount of it, and it works best in cool temperatures, so you don’t even need to waste money on heating the water.

How does the cold water thing work?
The solid substances need heating to dissolve completely. It’s about entropy, the thermodynamics of mixing, which is a different post.
Non-ionic detergents are usually liquid, so they are already in the right phase and don’t need heating. In fact, heating will actually damage them. They have a certain conformation in cold water, and a different conformation in hot water. It’s about thermodynamics again, but this time I’ll explain a bit: large molecules have many different ways of moving and shaping themselves. Each new shape has a different level of energy, meaning it takes a different amount of energy to move into that particular shape and maintain it. Heat is one form of energy the molecule can use to move and change its shape (conformation).
Non-ionic detergents, with their long head group, twist into a helical shape. The ‘cold’ conformation, the one that requires less energy, is the water soluble one, in which the oxygen atoms in the head turn outwards, in a way that lets them form hydrogen bonds with the water. In the ‘hot’ conformation, the helix twists so that the oxygen atoms now face inwards, and cannot form bonds with the water.

After you fiddled with the head group (and there are many more ways to do that), you can also fiddle with the tail group, making it more or less hydrophobic, longer, shorter, more twisting, give the molecule two heads or two tails, and many more options. The only thing that you need to maintain is the dual nature of the molecule, so it will be able to sit in the interface between two different solvents.

How do soaps and detergents clean?
This is where the dual nature of the soaps and detergents becomes important.
After you had a nice greasy meal, you want to wash your hands with water. But the water doesn’t dissolve the grease, and therefore, when the water flows away, the grease remains.
Soap is able to dissolve in water, but forms tiny bubbles of oil, which can trap the grease. When the water flows away, the bubbles flow with it, and the grease that is trapped in them is removed. Same thing happens when you wash your clothes, your floor or anything else, when you use soap or detergent.
But that’s not all! Soap and detergents also have some anti-bacterial properties. Since cell membranes are by and large composed of molecules similar to soap, they may be damaged by it, and the cells may die. That may be one of the reasons that harsh soaps or detergents damage your skin. It also damages many different bacteria, but not all bacteria.

Why does the washing machine need to move so much?
Water has a large surface tension, which means water molecules prefer to stick together, rather than mix with other substances. It also means water will usually not penetrate the thick weave of your clothes, because going through those tiny pores will force the water to break into tiny beads, which requires an investment of energy in order to break the surface tension.
Detergents are supposed to reduce water surface tension and help the water soak the clothes, in order to get to the dirt. Older detergents were less efficient in doing so, and the washing machine needed to invest physical force to break the water into tiny beads, which would then penetrate the clothes.
The more efficient the detergent, the less mechanical force is required in the washing.

How does all this tie to your household’s budget?
Your washing machine is designed to twist and turn, no matter which detergent you use, so you don’t have to buy the expensive stuff. In fact, if your clothes aren’t that dirty or don’t have any grease stains on them, you don’t need any detergent at all. The water is enough to dissolve any non-greasy dirt, and the washing machine’s gyrations are enough to force the water to meet that dirt.
Same goes for floor washing detergent and hand soap.
Only if the dirt is greasy, or particularly smelly (scent molecules are usually ‘oily’), you will need detergent to wash it off.
As for bacteria, soap doesn’t remove all of it, and washing your hands or clothes with water alone is still very effective in removing most of it. There is a difference between using and not using soap as far as bacteria go, but not a large difference.
(On the other hand, always washing your hands with soap is a ‘better safe than sorry’ situation, because you do come in contact with a lot of bacteria and greasy, without even noticing).
Reduce your soap and detergent consumption, and you will reduce your expenses.
Since detergents aren’t great for the environment, reducing your consumption of them will also benefit the planet.
To reduce your expenses even more, you can make your own bar soap, liquid soap, shampoo, laundry detergent, moist towels

Aluminum foil in the dryer?!?!?!
Yes indeed!
If we’re already talking about saving money with our laundry, let’s talk about the dryer.
I live in a very sunny country, so for most of the year we hang-dry our clothes in the sun. It’s both free and eco-friendly.
If you can’t hang-dry your clothes, you’re probably using a dryer, and your clothes get static if you don’t use that special scented paper. Personally, I like the smell of it, but I don’t like the price of it.
There are two ways to reduce the cost: use the spacial paper more than once, or use Aluminum foil, scrunched up in to a ball (and use it more than once, of course). The Aluminum foil will prevent the static just like the special paper!

Folded Failed Fudge

Another eureka moment came to me last week, as I was trying to fix my Failed Fudge yet again.
Again I reheated it with some water, stirring till it dissolved, and then letting it boil without stirring. Then I let it cool, probably too much, and it was too solid to beat with a wooden spoon.
Not one to give up easily, I started pulling it and folding it by hand. Didn’t do it for very long because I didn’t see a major change, and it was pretty solid already, so I pressed it down in the pan and left it to solidify over night.
What I got is Folded Failed Fudge:

It has thin layers of chewy fudge, between brittle thin layers of Failed Fudge, with chewy and crunchy texture. Very much reminiscent of the Reese’s Crunchy Crispy Bar. I told you success was nigh!
It’s as if the outer-most layer that formed on the fudge as it cooled remained brittle, but everything underneath remained nice and fudgy. When I folded it, all I did was increase the number of layers, just like making puff pastry.

Mercury pt.2- the Alchemy of Mercury

Introduction to Alchemy
Alchemy is the art of transmutation, the ability to turn one thing into another. Alchemy is the mother of chemistry, and despite its bad reputation, alchemy has done a great deal for science. Alchemists have discovered many interesting acids and compounds (Aqua Regia is one example), and invented many devices, which are still used today in the lab, and in the kitchen (Bain Marie and some distillation apparatus are great examples).
The main difference between chemistry today and alchemy is the belief in the duality of matter.
For chemists, a lump of metal is just a lump of metal. For alchemists, metal is the son or daughter of a heavenly body, which in itself is a deity.
But I’m getting a head of myself, that was the ancient Greek belief. Alchemy started long before the Greeks and the Romans came to power.
The word ‘alchemy’ comes from the term ‘al Chem’, from Chem, were Chem is the old name for Egypt. The modern European alchemy came from Egypt and the Middle East, but actually began much earlier than that, in China.

Chinese Alchemy
The first person to write about his alchemical experimentations was Wei Po-yang, in the first century AD. In his writing he refers to earlier alchemists, which lead researchers to believe that alchemy probably began around 400BC in china.
The Chinese alchemy is based on Daoism, the Chinese philosophy, and therefore includes the principal of duality, that the integration of two opposites in one entity, Ying and Yang, is the way to perfection. They believed that every solid object in this world also has a spiritual aspect, a magical force.
The Chinese believed that there are five elements: fire, water, earth, metal and wood, and these elements also represented various traits in a person, the tendency of an object to do one thing or another, and many things that we now consider metaphorical.
Chinese alchemists focused mainly on manufacturing potions of eternal life, and many of these potions contained cinnabar or mercury, plus various herbs. Mercury pills were also very common medications.
A very famous story involving mercury is the death of the first Chinese emperor, Qin Shi Huang, in the third century BC.
He was the first person to unify China, build the Great Wall and much more, but as he aged, he became more and more obsessed with his own mortality and searched for a way to cheat death. Doctors would prepare mercury pills and potions for him, and eventually he died of mercury poisoning.
According to legend, the emperor was buried in a magnificent tomb, which includes, among other things, a hundred rivers of mercury. His tomb is sealed to this very day, so it is difficult to tell how much of the legend is true. However, modern archaeologists sent in probes, which indicated that the amount of mercury found in the tomb is a hundred times the amount of mercury found naturally in the area.

Transmutation of metals probably also started with the Chinese alchemists. They believed that after roasting, the metals would gain spiritual qualities. Therefore it was important for gold or cinnabar to go through this process if they were to be used as medications, or give eternal life to those who ate them.
Gold was not very common in China, but mercury and cinnabar were more prevalent, so Chinese alchemy focused more on mercury, as opposed to European alchemy.
The red color of the cinnabar, which resembled the sun, also represented fire, energy and nobility.
Mercury was so important do the Chinese alchemists that the word for mercury (‘dan’) is a part of the term for alchemy (‘waidan’).
The Daoism in alchemy is evident in the fact that the alchemists regarded mercury and cinnabar as opposites. The mercury, due to its white color, symbolized the moon, and the cinnabar, with its red color, symbolized the sun.
Sulfur (yellow) also symbolized the sun, and since sulfur, together with mercury, created cinnabar, sulfur was also considered the opposite of mercury.
Mercury was considered an active substance, and the sulfur was considered passive. Notice that they have personality traits, as if they were living creatures.

In the 4th century AD, there lived the alchemist Ko Hung, who believed that man is what he eats, meaning that a man who eats gold will reach perfection (gold is perfect because it doesn’t react with anything, it doesn’t need anything to complete it. it’s a noble metal). The trouble was that a true believer will be a poor person, and will not be able to afford gold. Therefore, gold had to be substituted with gold that was produced from cinnabar. The process would require roasting and other methods, which will imbue even more spiritual qualities to the gold, so it will be even more magical.
Ko Hung found other uses for cinnabar. For example, one could rub his feet with cinnabar, which would allow him to walk on water. A little cinnabar over the threshold of a house will repel thieves. If an old man would mix cinnabar with raspberry juice and drink it, he would be able to produce offsprings. Ko Hung found many more interesting and exiting ways to get mercury poisoning, and it’s a wonder he didn’t die of it himself.
(This is me, reminding you that mercury, cinnabar, and anything else alchemists thought would lead to eternal life, is extremely toxic and should not be ingested, inhaled, topically applied, or anything else. Just stay away from it.)

European Alchemy
The Chinese alchemy slowly spread out to Europe, and the alchemy of Empedocles and Aristotle developed around 300 years BC. Just like the Chinese alchemy, it consisted of 5 elements, with slight alterations: fire, water, earth, air and ether. Ether was an intangible element, which gave every substance and every object its essence, its ‘soul’.
European alchemists believed that all the materials in the world can be created using a combination of these elements, and that the elements are the womb in which various materials were created. The earth, for example is the womb in which metals grow. The planets (or rather, the gods that were represented by those planets) are the ones who impregnate the earth. Each planet (each deity) would produce a different metal. The god Mercury (the messenger of the gods, the fastest runner) was represented by the planet mercury (nearest to the sun, with the fastest orbit around the sun), and produced the metal Argentum Vivum (mercury, of course).
The European alchemical symbol for mercury is the staff of Mercury:

alchemical symbol for mercury

The circle and the cross together form the sign of a female. Originally this was supposed to be a hand held mirror, and since women used mirrors, this became the sign of a female in general, or more specifically Venus. As the symbol for mercury, it reverts back to the sign of a mirror, because mercury is so shiny and reflective.
The horns on top of the mirror represent the crescent of the moon, which was symbolized by silver, which was considered to be related to mercury.
The cross may also represents the link between matter and spirituality, and the circle represents perfection (which the alchemists tried to achieve).
Mercury is the only element in the periodic table that kept its alchemical name.

Arab Alchemy
From Europe, alchemy seeped to the middle east, where in the 4th century AD, the famous alchemist Jābir (Abu Musa ibn Jābir Hayyān) expanded the European system of alchemical elements to add mercury, sulfur and salt.
Jābir believed that a metal consists of four of the Greek elements. The difference between each metal was the different ratios between those elements. Therefore, in order to transform one metal to another, you had to change the ratios.
The object that would cause the transmutation is the Philosopher’s Stone – a mythical object with the ability to grant eternal life and to transform lower metals into gold. The Philosopher’s Stone consists of mercury, sulfur, salt and time. Mercury represents a change (just like in the Chinese alchemy), sulfur symbolizes the purification by fire, salt symbolizes the resistance to fire, and time symbolizes the dedication of the alchemist needed to create the Philosopher’s Stone.
The Philosopher’s stone has the duality of matter and spirit: mercury and sulfur are both solid materials, and at the same time they are the symbols of change and purification by fire. Mercury rests at the center of this belief, as an ideal matter which encourages change, and from it, all other metals can be produced, with the addition of sulfur in different ratios. Gold, for example, would require more sulfur than mercury, since both gold and sulfur are yellow. Silver however, contains more mercury than sulfur, since both silver and mercury are white.
Jābir’s belief may be based on the distillation of mercury from amalgams with gold or silver, which must have looked like mercury was producing gold and silver as it evaporated.
Despite his belief in the mystical, Jabir was also a distinguished chemist, who discovered, among other things, mercury oxide (which in the future will be used to demonstration Lavoisier’s theory of combustion), and mercury chloride (the compound HgCl2, also known as ‘corrosive sublimate’, which was widely used in photography.).

‘Modern’ Alchemy
From the Arab world, alchemy returned to Europe during the middle ages and more modern times, in the form of superstitions and strange medicines. Medicinal alchemy was known as Iatrochemistry, and I’ll tell you all about it next time.
In the meantime, I’ll leave you with one strange superstition:
In the 19th century people believed that a loaf of bread, filled with mercury and thrown in a river or a lake, would drift next to a corps, to reveal its location. This popular superstition is documented in the press, as well as in fiction, as a valid method for discovering dead bodies. In “the adventures of Huckleberry Fin” by Mark Twain, when Huck reaches Jackson Island, his friends believe he drowned, so they float some bread full of mercury in the hope of finding his body. When the loves drift to Jackson Island, Huck picks them up, shakes out the mercury drops and eats the bread. Not the smartest idea, but safer to eat mercury than to breath it.
All on the wonderful ways to die of mercury poisoning in Mercury pt.3.

Cookie Dough Fudge Mint Chip 1.2

The results are in:
The fudge dissolved a bit into the ice cream and made beautiful caramel colored streaks. It also tasted great and melted nicely on the tongue.
The cookie dough needs to be sweeter, but it had good texture and it was a good amount.
The cream was not minty enough, probably because my essence was too old. My friend not used to tasting the cream in ice cream, and thought it was a bit odd. She’s also a big mint fan, and it wasn’t minty enough for her. Next time, maybe add some vanilla, and use a fresher mint essence.
The chocolate bits were hardly felt, and the lack of something crunchy was noticeable. I would prefer to replace them with walnuts, but it wouldn’t be Cookie Dough Fudge Mint Chip if I did. The only option is to double the amount of chocolate bits for the sake of crunch.
Something that didn’t come up, but your all thinking: isn’t mint ice cream green? No. it’s green if you use artificial colorant, which I refuse to do. There might be a way to use actual mint and its chlorophyll to get a green color, but it seemed like too much hassle, along with the cookie dough and the fudge. Maybe next time.

The revised recipe:

Eggless cookie dough (prep time: 10min):
2 cups all purpose flour
1 cup brown sugar
1 cup white sugar
3/4 cup butter, melted
4-5 tbsp milk
Mix flour and sugars in a bowl. Stir in the melted butter until you get a crumbly mixture. Add the milk, one spoonful at a time, and mix well, until you can form a ball of dough.
Use about a 1/4 of the amount for this ice cream, and freeze the rest for later use.

Failed fudge (prep time: about 1 hour. For proper fudge it would take 2hr+all night to cool):

85gr (3oz) dark chocolate (semi-sweet, bitter, whatever you’ve got)
3 cups white sugar
1 tbsp corn syrup
1 cup half-and-half or light cream
1/4 tsp (a good pinch) of salt
1 tsp vanilla flavoring
3 tbsp butter
In a large saucepan, cream, salt, corn syrup and sugar. Break the chocolate in to small bits and add it to the pan, while stirring to dissolve everything.
Once everything has dissolved, stop stirring and let it boil for about 10min. using a wooden spoon, drop a small mount of the syrup on a cooled plate. Let the drop cool, and then run it through with a skewer or something thin, to form a line. If the drop is still soft, but holds the line and doesn’t flow to fill it, turn the heat off and let the fudge cool. If the drop is still very fluid, keep cooking and testing, until you reach the right consistency.
If the drop is too rigid, turn the heat off and let the syrup cool a bit. Meanwhile, boil some water. After the syrup cooled enough for you to touch it without burning your finger, add 1/2 of the boiling water and mix it in. Return the pan to the flam and cook again to the right consistency.
Once the fudge has cooled enough for you to touch it comfortably, stir in the butter and vanilla essence. Don’t let the fudge cool too much; otherwise it’ll actually turn to proper fudge. Continue stirring until the fudge starts to solidify. This shouldn’t take long. Try to transfer the fudge to a square pan (covered with waxed paper) before it solidifies completely, but even if you can’t, it’ll be OK. Just break the fudge into chunks and get it out of the pan in to a different container that will be comfortable to store.
Use about 1/5 of the fudge (broken or cut in to small bits) for this ice cream, and store the Failed Fudge for something else. Maybe even reheat it with some water and make proper fudge out of it. See previous post, what did I do wrong? to learn how to fix Failed Fudge.

Mint chip ice cream (prep time: 30min, cooling time: one night, churning time: 30min):
Prepare the cream mixture the night before you plan to eat the ice cream, it needs to cool for a long time. Also, put the ice cream maker’s bowl in the freezer over night.
1 cup milk
2 eggs
100gr sugar
2 cups whipping cream
1/2 tsp vanilla essence
2 tsp mint essence (more or less, depending on the strength of the essence)
100gr chocolate chips or dark chocolate (or walnuts), chopped into small pieces
Heat the milk in a small pan.
Meanwhile, lightly whisk the eggs with the sugar. They just need to blend together.
Once the milk is very warm, add a small amount of it to the eggs, while whisking briskly. Continue adding the milk and whisking, until all the milk has been added. Return the egg and milk mixture to the pan and heat it, without boiling, while constantly stirring, until the custard coats the back of a wooden spoon in a thin layer. Basically, it needs to thicken just a bit. Remove it from the flame and let it cool a bit. It will thicken as it cools, because it continues cooking from its own heat.
If the custard formed lumps, don’t be discouraged. Just run it trough a sieve and discard the lumps (or it them. Milk, sugar and eggs, nothing wrong with that.).
Stir the custard in to the cold cream, and add the flavorings. start with just one tsp of mint essence, taste the cream mixture and then decide if you want to add more. Stir the mixture well and let it cool further in the fridge, over night.
The next day, churn the ice cream according to your ice cream maker’s instructions. Meanwhile, form the cookie dough into small balls no bigger than your thumb and likewise with the Failed Fudge. Cut the dark chocolate to about half that size.
Once the ice cream finished churning, transfer it to a suitable container (like a 1.5L plastic container) and mix in the cookie dough, Failed Fudge and chocolate.
Eat now or freeze for later.

Cookie Dough Fudge Mint Chip 1.0

It’s getting hot around here this time of year, and I’ve started an ice cream project to combat the heat. I’m on a quest for the best variation of Cookie Dough Fudge Mint Chip. Why this combination of all the infinite possibilities? If you don’t know, I’m not going to tell you. You’ll just laugh at me.

Any way, there can be a number of interpretations to this, and this week I’m making a mint flavored ice cream, with bits of fudge, cookie dough and dark chocolate swirled in it.


The cookie dough recipe came from The Cupcake Project and the fudge recipe from The Accidental Scientist. I highly recommend both sites for their scientific value, as well as their culinary value. The first takes a very scientific approach to cupcakes, and the second just uses cooking as an excuse to explain science in a fun way. I like The Accidental Scientist, but it only scratches the surface of cooking science. If I were to explain the science of every single ingredient that went into this particular recipe, I wouldn’t have time for anything else this week. Instead, I’m going to spread it out over the next few weeks, and share only one sugary-goodness of information at a time.

This time it’s going to be:

Oh, Fudge!

Yep, I totally fudged this one. I tried, and then I tried to fix it, and when it was looking better, I did another mistake and it was too late to fix it again. Oh well, I’ll know better next time. On the up side, the failed fudge still works in my ice cream, AND! And this is an Important AND! I now know how Reese’s get that crumbly texture for their peanut butter in the peanut butter cups. It’s over-cooked peanut butter fudge! I’ve been trying to figure that out for years. Now if I can only get some caramel crystals in there, I could make their Crispy crunchy bar. Successes is nigh!

OK, let’s get on with the science:

The ingredients first call for chocolate, which is an emulsion of sugar (water soluble) and cocoa butter. As we all know, water and oil don’t normally mix, so different methods are employed to force the sugar to blend with the butter in a nice, smooth texture. There is constant stirring, to prevent large sugar crystals from forming, and there are emulsifiers, such as soy lecithin, that are added to the mix.

There is also half-and-half, or cream in this old fashioned fudge. Mile and all its fatty variants are emulsions. I suspect that the cream in this recipe is supposed to help the chocolate and the sugar blend together better. Using a pre-existing emulsion to emulsify other things. More on emulsions and emulsifiers in the next ice cream post.

Next on the list, we have sugar. White table sugar contains sucrose, a disaccharide that combines glucose and fructose in one molecule. Corn syrup also contains glucose and fructose, but not in the same molecule. In the past, it was thought that corn syrup was more detriment to one’s health than regular sugar. The theory was that because the sugar in corn syrup was already broken down to its components, it would get to the blood stream faster, and cause a large spike in the blood sugar level. According to recent studies, there is no difference between the uptake of corn syrup and the uptake of regular sugar, so they are both just as damaging. Another myth was that corn syrup was sweeter than regular sugar, because it was already broken down to the basic components. Wrong again. They are both just as sweet.

But if there’s no difference, why do we use corn syrup in candy-making? Two reasons: 1. It’s cheaper to produce, which makes candy companies happy. 2. Glucose and fructose behave differently than sucrose when melting, when forming crystals, or when mixed with fats. The molecules are different, so they have a different chemical behavior.

From The Accidental Scientist: “Corn syrup acts as an “interfering agent” in this and many other candy recipes. It contains long chains of glucose molecules that tend to keep the sucrose molecules in the candy syrup from crystallizing. “

What else do we have there? There is salt and vanilla for flavoring, and a bit of butter for a smoother texture.

For instructions and their explanations, go to The Accidental Scientist. Their explanations are excelent!

So what did I do wrong? Everything.

I’ve made English toffee and caramels before, without much trouble, but the fudge was much more sensitive. Perhaps it’s because of the chocolate (more fat in the recipe?) or because it uses much less corn syrup (more difficult to control the crystals).

The first problem is I’m too proud (and too cheap) to buy a candy thermometer. I have to guess at the temperatures according to the behavior of the syrup in water or on a cool surface. I’m getting better at this every time, so there’s hope.

This time I probably over cooked the fudge, and the water content was too low. Second thing was that I didn’t wait for it to cool properly before I started to beat it. It was beautiful to see how fast the crystals formed and the oozing mass suddenly solidified, the way super-cooled water turns to ice when disturbed. It still tasted good, but the texture was grainy and brittle, just like the Reese’s peanut butter cups filling (mini Eureka moment!).

To fix this, I broke the failed fudge into small pieces, added some water to the saucepan, and reheated the whole thing to a boil, while stirring. I stopped stirring when all the pieces melted, and let it boil for another 5min or so, when I estimated that it reached the soft ball stage again. This time I let it cool properly, for over an hour, till it reached body temperature (again, no thermometer). I started beating it, and continued till the fudge looked right. Since I never saw how fudge is made, that may not have been what fudge is supposed to look like, and I was a little worried that I under cooked it this time. It was still looking good and fluid after 30min of rest in the pan, so I put it in the fridge over night, in the hope that it would solidify. Bad idea. It cooled too fast and in the morning in was gritty and brittle again.

This is exactly what happens with regular chocolate as well. When the weather is hot and chocolate starts to melt, some people put it in the fridge, only to discover that it turned gray and flaky the next day. The gray spots are called ‘blossom’. The fats in the chocolate melted, which allowed the sugar crystals to move and grow. The rapid cooling locked the crystals in their new formation, which is less mouth-watering for the consumer. The chocolate itself is perfectly fine and safe to eat, it just doesn’t look as great as before. This can be fixed by melting down the chocolate and letting it cool slowly, a process known as ‘tempering’.


I could have fixed my fudge a second time, but it was getting late. I had promised my friends I would bring them my first ice cream experiment today, so I had to work with what I had.

I think it turned out pretty good. I actually like that the failed fudge is soft and melts in my mouth easily, as apposed to the chocolate bits, which are too hard and take too long to melt, so they feel like tasteless plastic lumps. I’m not a big fan chocolate chips in my ice cream, but the friends I’m visiting today are, so I’ll see what they thing of my creation.

Recipe, pictures and critique, when I come back.

Phys In Your Fizz

Have you heard about Guinness White?

Guinness put out this ad a few years ago:

Good Things Come to Those Who WHITE
A pint of the black stuff becomes a pint of the white stuff with the launch of a creamier new version: “Guinness White”.
Guinness is made from the same raw ingredients as regular Guinness Draught – hops, barley, water and yeast, but the barley is frozen instead of roasted, which provides the white colour.

 But this beer isn’t a new invention. In San Seriff they have been making Guinness White since 1977. Back then, they sowed the barley seeds upside down, to get the inverted colors.

 Some bartenders came up with their own method of making Guinness White: They use a special glass with etching on the inner surface, which stops just where the (black) head starts.
The roughness of the surface is what makes the bubbles form.
You can order a white Guinness, then order a normal Guinness, and and the only thing that changes is the glass, not the beer. 

OK, so all three are clearly an April fool’s prank, but the last one is based on actual science. A modern beer glass very often has a few concentric rings etched on the base, which functions as a nucleation site to promote the formation of bubbles, and form the ‘head’ of the beer. Nucleation sites are where something starts to form, where a bunch of molecules meet and then stick together. Once a tiny bubble forms, it continues to grow because the gas molecules diffuses from the liquid into the new bubble. What drives the inflation is the difference between the higher pressure of the gas dissolved in the liquid compared with that inside the bubble. When the bubble develops enough buoyancy, it detaches from the nucleation site and continues to grow as it rises. This growth makes the bubble increasingly buoyant, causing it to rise more and more quickly toward the surface.

A Minty Spin On An Old English Favorite

Remember the Mentos-Coke fountains? (two of my favorite videos are here and here). Mentos, or anything added to a fizzy drink (sugar, salt, sand…) acts as a nucleation site for the carbon dioxide dissolved in the liquid. Gas takes up more space than liquid, even though the number of molecules doesn’t change. Once you have a lot of gas contained in the same space the liquid was in, the pressure increases and the gas escapes violently, and takes some of the liquid along with it.

Why was there gas in the liquid to begin with? The English chemist William Henry (1775-1836) formulated one of the gas laws (Henry’s law), which says that gas can dissolve in a liquid, and the amount that dissolves depends on the temperature and pressure of the system, and the type and volume of the liquid. Our fizzy drinks are all water-based and packed at a high pressure, to insure a maximum amount of gas dissolved. When you open the bottle, the pressure drops, and the carbon dioxide leaves the liquid and reverts to the gas form. The gas will continue to leave until it reaches equilibrium with the new pressure level (Le Chatelier’s principle: If a chemical system at equilibrium experiences a change in concentration, temperature, volume, or partial pressure, then the equilibrium shifts to counteract the imposed change and a new equilibrium is established). This process may take some time (days), but if you add nucleation sites it will go much faster (seconds), hence the Mentos-Coke fountain.

The same thing happens with divers and the nitrogen from the air they breathe. The air we breathe is about 78% nitrogen, the pressure is 1 atmosphere, and very little of the atmospheric nitrogen dissolves in the blood. As you dive into the ocean with an air tank, the deeper you go, the higher the pressure, and more nitrogen is dissolved in your blood. When you rise back to the surface, the pressure decreases and the nitrogen in your blood reforms as tiny gas bubbles, which might clog you blood vessels and cause a heart attack (a condition known as ‘the bends’). For this reason, it is recommended not to dive too often (as to not accumulate too much nitrogen in the blood) and also not to fly on a plane too soon after a dive (the higher you go, the lower the pressure, the bigger the gas bubbles).

The carbon dioxide in beer, Champagne, hard cider and other alcoholic beverages comes from the action of yeast. The yeast eat sugar and emit carbon dioxide as waste products. This is also what makes bread rise. This is the beginning of biotechnology, and of a different post.

Dissolved carbon dioxide functions as an amphoteric acid/base duo and has some very interesting functions in our bodies. That’s another biochemical post altogether. 

Sinking Bubbles

Another interesting phenomenon related to Guinness and to inverted things is the marvel of the sinking bubbles. We are very much used to seeing gas bubbles floating up to the surface of a liquid- an event related to the difference of density between the gas and the liquid- but sinking bubbles were thought to be nothing more than an optical illusion. In 1991, Dr Andrew Alexander (Edinburgh University, Scotland) and Professor Richard Zare (Stanford University, CA, USA) managed to film the phenomenon and prove that it is real (check out their site for the video and more). Some time later, Professor Clive Fletcher (University of New South Wales, Sydney, Australia) used a computer simulation called FLUET to explain how and why the bubbles go down instead of up. The conclusion was that the “normal bubbles”, which float up in the center of the glass, create a current in the beer, so the beer rises in the center and falls near the glass circumference. The bubbles close to the side of the glass are pushed downwards by the beer, and sink to the bottom.

Not every glass of Guinness will necessarily exhibit this effect. According to the researchers, the simulations only apply to beer in the trademark, barrel-chested Guinness glass.

The Gender Bias Champagne

photo by Gérard Liger-Belair  

Professor Richard Zare also found that Champagne tends to go flat when women drink from it. Most people drink Champagne on special occasions, and on those occasions, women usually wear lipstick. The lipstick contains an anti-foaming agent, which kills the bubbles in Champagne or any other bubbly liquid.

Champagne Bubbles Vs. Guinness Bubbles

There ways in which the beverages and their bubbles are dramatically different. For example, the champagne bubbles rise faster, expanded much more rapidly and form at higher rates than their beer counterparts, as was reported by Professor Gérard Liger-Belair (University of Reims, France) in 1999. He used a high-speed camera, strobe light, photographic enlarger, and ruler to measure sizes, speeds, and rates of formation of champagne bubbles.

Beer and champagne differ from each other in three properties: the amount of dissolved gas, the percentage of alcohol, and the concentration of large molecules, such as protein and starch. Champagne has three times the dissolved carbon dioxide and more than twice the alcohol content of beer. However, beer has 30 times champagne’s concentration of protein.

The higher gas concentration in champagne may cause the bubbles to form more quickly, the faster to leave the liquid and reach equilibrium with the atmospheric carbon dioxide

The large concentration of protein in beer acts as surface-active compounds, coating the bubbles and making them stiffer. The stiffer the bubble, the more drag it encounters, the slower it rises to the surface. Champagne, by contrast, has too little protein, and its bubbles grow too quickly to be covered by what little protein there is, so they remain flexible and rise to the surface quickly.

Ucorked: the science of champagne, by Gérard Liger-Belair seems like a really interesting book about, and it’s in plain English, for everyone to enjoy.

Who cares?

Why would renowned scientists spend their time worrying about bubbles in beer and champagne? Because it’s interesting and because even though we take those bubbles for granted, they have considerable value in the food and beverage industry. Plus, many things that seem trivial in one field have important applications in another. In the case of sinking bubbles and anti-foaming agents, the subject is very relevant to the study of emulations, which is extremely important to the food and pharmaceutical industry, dyes and paints, nano-biotechnology and many, many other fields. You start with beer, and then you take over world!

Mercury, from antiquity to the present, part I

alchemical symbol for mercury

Mercury: a chemical element, metal  

Chemical symbol: Hg  

Atomic number: 80  

Melting point: −38.83 °C  

Boiling point: 356.73 °C  

Appearance: silvery-white liquid  

Mercury metal is unique in that it appears as a liquid at the room temperature, unlike most metals, which are solid (only four other metals might be liquid on a warm day: caesium, francium, gallium, bromine, and rubidium). Another unique trait is that Mercury can create amalgams, which are liquid alloys with other metals, and have some very interesting uses.  

Mercury compounds are known since pre-historic times, and along with pure metallic mercury, they are deeply entwined with human history. Mercury is very prominent in the fields of alchemy, chemistry, and medicine, and it has a way of reflecting the beliefs and thoughts of a society whenever and wherever it appears.  

In this post I intend to introduce you to the fascinating history of Mercury, and to the history of chemistry in general.  

The ancient origins of Mercury  

Since Mercury in its metal form is rarely found in nature, the mineral Cinnabar (HgS, an ionic compound) was the most common form in use during pre-historic times. This mineral has a reddish-brown color, and when it is artificially made, it’s called Vermilion.  

Due to its intense color, Cinnabar was used as a pigment during pre-historic times in Europe, central America and china. The Mayans in Honduras used to paint the skeletons of their royalty, but the Italian ancestors preferred to paint the skulls of their cattle.  

Cinnabar-painted Mayan woman in Copan  

At around 500 BC, the Romans began to mine the Cinnabar in Almaden, Spain (probably the oldest functional mine, it was operational for 2500 years and only recently closed). At this point in time, they did not know how to extract the Mercury from the mineral, despite the fact that drops of mercury formed spontaneously on the mineral itself. Workers in the mines were prisoners, minor offenders such as thieves, which were only sentenced to slave labor. In effect, they were sentenced death, due to mercury poisoning. Life expectancy of the workers was 3 years from the day they started working.  

Only after two hundred years, at around 300 BC, Greek philosophers began to mention the metallic mercury in their writings. Theophrastus and Aristotle mention the mercury as Argentum Vivum or “living silver” (also known as Quicksilver, ‘quick’ being the English word used a long, long time ago to describe something living. They really did believe it was a living entity. More on that in Mercury pt.II). The name Argentum Vivum refers only to the naturally occurring metallic mercury, because they still did not know how to extract the mercury out of the Cinnabar.  

The first production of mercury from Cinnabar was by sublimation, and is first mentioned around 50BC, in the writings of Dioscorides and Vitruvius. Principally, the Cinnabar was heated in an iron caldron, covered with a lid. The ionic mercury was reduced by the iron to metallic mercury, and then the mercury condenses on the lid (just like water vapor condenses on the lid of a cooking pot). Mercury produced in this manner was considered different than the naturally occurring mercury (Argentum Vivum), so it was called Hydrargyrum (liquid silver) by the naturalist Pliny. The name Hydrargyrum is the origin of the chemical symbol we use today: Hg.  

In Pliny’s time, metallic mercury was known to form amalgams with other metals, a trait that was used in the extraction and cleaning of silver and gold from various ores. Gold and silver are naturally found in their metal form, but they are mixed with different minerals. To extract the precious metals, the minors would pulverize the rocks to a fine powder, and then mix the powder with the liquid mercury. The gold or silver would form amalgams with the mercury, and thus separate from the minerals. To separate the silver or gold from the amalgam, the minors would boil the amalgam and allow the mercury to evaporate. What was left in the pot was (relatively) clean silver or gold. This was an extremely dangerous task, since mercury vapors are very toxic.  

The cinnabar compound was known to be toxic since it was first mined, but only around 150 AD the Greek healer Galen (Galen of Pergamum) determined that metallic mercury is toxic. Remember this, because others have forgotten. More on this in Mercury pt.III.