I was volunteered to present a simplified version of my research to a group of visiting politicians yesterday. I was given exactly 3.5 minutes to present starting at 3:13 pm, I guess politicians live in a precise world (as we all expected they showed up somewhat late). So here is what I said:
The focus on my research in on how the tides interact with Fraser Ridge (a sub-surface bump in the Strait of Georgia). One really interesting effect is the formation of lee waves on the flood tide. Ocean waters tend to be stratified, which means the water is organized so the denser water sits lower than the less dense water. As tides move this water over an obstacle like Fraser Ridge, water is forced to speed up because of the constricted space and it gains momentum. On the lee side of the obstacle the momentum can carry less dense water down deep. Eventually, friction causes the water to slow and the less dense water bounces back up in a formation called a lee wave. Effects like these lee waves can provide an explanation why some coastal sites form productive ecosystems.
What is interesting about Fraser Ridge is that a rare glass sponge reef has made its home there. Glass sponge reefs were once common in the world's oceans at the same time that dinosaurs roamed the earth. Like the dinosaurs, we thought glass sponge reefs were extinct. In the 1990s, living glass sponge reefs were discovered in a few locations off the coast of BC and it turns out they make great habitat for young rock fish. Glass sponges are filter feeders fixed to the bottom so they need enough flow to bring in their food, remove their waste and keep them from being buried in sediment. Periodic formation of lee waves can provide the flow they need.
At my study site, a lee wave forms on each flood tide. The sponges have chosen to live on the steepest slope which corresponds to the strongest currents, turbulence and sharpest lee wave.
Thursday, September 30, 2010
Tuesday, September 28, 2010
Working comfortably in remote places
I've been reading 'Packing for Mars' and enjoying it greatly. The author describes the ups and downs of working in space. I've never worked in space, but I certainly can relate to some of the difficulties of working in remote, confined and difficult places. Add on top of that sleep deprivation, situations can become really dangerous and/or hilarious (for some reason sleep deprivation can leave me giggly).
When I first started doing field work in the army I made the mistake of thinking that if I only had a short time to sleep, I should just lay down with my boots on and attempt to sleep anywhere – like on a pile of rocks (looked comfortable in the dark) or the main thoroughfare for an army of ants. It didn't take me long to realize taking the time to blow up an air mattress, pull out a sleeping bag, and take my boots off would make me so much more comfortable.
I've spent months working out of tents, which can be comfortable especially if I've brought a cot. I've even packed a pillow when heading out to these places. A large tented camp can be just like a small town – hot food and showers are often available. If the ground isn't frozen, mud always makes an appearance (I've never lived in a tented camp in the desert but I suspect the issue then would be sand). Everything can end up covered in mud and without running water it is hard to clean up. I've had mud fill all the treads on my boots to the point where I just slip slide around.
Working on small boats exposes one to the weather, which is okay with the proper clothing and a warm place to spend the night (or day if working on the boat at night). Open boats aren't my favorite; on a nasty day it is nice to get inside if only for a few moments.
By far, my favorite field work space are full sized ships – I like knowing there is a comfortable place to sleep nearby especially if my shift is long. Hot showers (even if they are short), clean clothes and hot food prepared by someone else are other pluses. There are always people around on a ship which I find to be a comfort if we are out in the middle of the ocean or up in the arctic. The downside to working on a ship is my tendency towards sea sickness which can be dealt with.
Where ever I go, being comfortable appears to be a choice. It's never that much harder to make oneself more comfortable – start with taking the boots off.
When I first started doing field work in the army I made the mistake of thinking that if I only had a short time to sleep, I should just lay down with my boots on and attempt to sleep anywhere – like on a pile of rocks (looked comfortable in the dark) or the main thoroughfare for an army of ants. It didn't take me long to realize taking the time to blow up an air mattress, pull out a sleeping bag, and take my boots off would make me so much more comfortable.
I've spent months working out of tents, which can be comfortable especially if I've brought a cot. I've even packed a pillow when heading out to these places. A large tented camp can be just like a small town – hot food and showers are often available. If the ground isn't frozen, mud always makes an appearance (I've never lived in a tented camp in the desert but I suspect the issue then would be sand). Everything can end up covered in mud and without running water it is hard to clean up. I've had mud fill all the treads on my boots to the point where I just slip slide around.
Working on small boats exposes one to the weather, which is okay with the proper clothing and a warm place to spend the night (or day if working on the boat at night). Open boats aren't my favorite; on a nasty day it is nice to get inside if only for a few moments.
By far, my favorite field work space are full sized ships – I like knowing there is a comfortable place to sleep nearby especially if my shift is long. Hot showers (even if they are short), clean clothes and hot food prepared by someone else are other pluses. There are always people around on a ship which I find to be a comfort if we are out in the middle of the ocean or up in the arctic. The downside to working on a ship is my tendency towards sea sickness which can be dealt with.
Where ever I go, being comfortable appears to be a choice. It's never that much harder to make oneself more comfortable – start with taking the boots off.
Thursday, September 16, 2010
Water drops on kale
I was out in my garden this morning in the few moments of sun before more rain and I noticed beads of rain water had formed on the kale leaves. See how the veins on the leaf are moved when looked at through the water? See the sky reflection? If I had leaned close enough, my reflection would probably be visible too.
Wednesday, September 15, 2010
Sticky Honey
At first honey flows as a thick glop that evolves into an seemingly infinite stream. I never bother to wait long enough for it all to come off my measuring spoon, instead I just lick it – actually I could just lick spoons of honey without putting it into anything (like everyone else, I'm hardwired to like sweet things). Honey is sweet in a complex way I find intriguing. I'm always on the lookout for different types of honey to try. Recently, I bought a big plastic tub of clover honey on my trip east. Years ago, while wandering around downtown Munich, I found an entire shop devoted to different types of honey – I was amazed by the sheer number of types of honey: lavender, clover, buckwheat, avocado, heather and the list could go on. I think people really like honey.
Honey has been consumed since ancient times, likely as far back as 10,000 years ago or more. At one time honey was often the only sweetener available. When the tomb of King Tutankhamun was found in 1922, a pot of honey was discovered inside that was still edible (I'm not sure I'd go for potentially cursed mummy honey). On top of sweetening, honey has been used medicinally for eons. Modern studies have shown that honey helps healing wounds, it even provides a soothing effect when applied to burns. It also is a possible treatment for gingivitis, cataracts, ulcers and more.
According to 'The Flavor Bible', honey is a moderately loud flavor considered 'rustic' that goes with both the savory and the sweet. Every honey made tastes unique because the flavour of honey is determined by the flower the nectar came from, and there are almost an infinite number of possible flower combinations. Bees can be picky about what flowers they use. In one study, beehives were situated in the middle of avocado orchards while the avocado trees were blooming. Avocados produce a lot of nectar, so it should have been a win-win for the trees and bees. It turned out the bees preferred nectar from flowers surrounding the orchard.
Once nectar is brought back to the hive, the bees ingest and regurgitate the nectar multiple times until it is partially digested. At this point, it's stored in the honey comb while worker bees fan it with their wings until enough water evaporates. When the water content is low enough, honey will never spoil. When finished, honey has the following composition: 17.1% water, 82.4% total carbohydrate and 0.5% proteins, amino acids, vitamins and minerals.
At 64 calories per tablespoon, honey is a good source of nutrition. Honey colour is an indication of how strong the honey will taste. Light honeys are mild and dark honeys are stronger. It turns out that the darker honeys often have more antioxidants and potassium, but beware, honey can darken during shipping and storage.
What I think is cool about honey (beyond snacking possibilities) is that it's a non-Newtonian fluid. A non-Newtonian fluid is a fancy way to say that it doesn't respond evenly when poured in contrast to a Newtonian fluid like water. If you take a spoon of water and turn it over the water will flow out at an even rate. If you take a spoon of honey and turn it over, at first it will just bulge then a thick stream will slowly descend downwards. Over time the stream will speed up and thin.
In a non-Newtonian fluid the relationship between shear stress (pushing parallel to flow) and strain rate (how fast it deforms) is non-linear. That is, a simple number, usually viscosity (resistance or thickness of the fluid), can't be used to relate shear stress and strain rate together. To add complexity, this effect can even vary with time. The large molecules of the honey form links with each other that have an elasticity to them and can actually counteract for a while forces like gravity. Eventually, the flow overcomes this resistance and links will break. Other links will form and this non-linear effect will persist.
I'm going to keep looking for different types of honey when I travel and I won't expect it to come out of the jar easily.
Honey has been consumed since ancient times, likely as far back as 10,000 years ago or more. At one time honey was often the only sweetener available. When the tomb of King Tutankhamun was found in 1922, a pot of honey was discovered inside that was still edible (I'm not sure I'd go for potentially cursed mummy honey). On top of sweetening, honey has been used medicinally for eons. Modern studies have shown that honey helps healing wounds, it even provides a soothing effect when applied to burns. It also is a possible treatment for gingivitis, cataracts, ulcers and more.
According to 'The Flavor Bible', honey is a moderately loud flavor considered 'rustic' that goes with both the savory and the sweet. Every honey made tastes unique because the flavour of honey is determined by the flower the nectar came from, and there are almost an infinite number of possible flower combinations. Bees can be picky about what flowers they use. In one study, beehives were situated in the middle of avocado orchards while the avocado trees were blooming. Avocados produce a lot of nectar, so it should have been a win-win for the trees and bees. It turned out the bees preferred nectar from flowers surrounding the orchard.
Once nectar is brought back to the hive, the bees ingest and regurgitate the nectar multiple times until it is partially digested. At this point, it's stored in the honey comb while worker bees fan it with their wings until enough water evaporates. When the water content is low enough, honey will never spoil. When finished, honey has the following composition: 17.1% water, 82.4% total carbohydrate and 0.5% proteins, amino acids, vitamins and minerals.
At 64 calories per tablespoon, honey is a good source of nutrition. Honey colour is an indication of how strong the honey will taste. Light honeys are mild and dark honeys are stronger. It turns out that the darker honeys often have more antioxidants and potassium, but beware, honey can darken during shipping and storage.
What I think is cool about honey (beyond snacking possibilities) is that it's a non-Newtonian fluid. A non-Newtonian fluid is a fancy way to say that it doesn't respond evenly when poured in contrast to a Newtonian fluid like water. If you take a spoon of water and turn it over the water will flow out at an even rate. If you take a spoon of honey and turn it over, at first it will just bulge then a thick stream will slowly descend downwards. Over time the stream will speed up and thin.
In a non-Newtonian fluid the relationship between shear stress (pushing parallel to flow) and strain rate (how fast it deforms) is non-linear. That is, a simple number, usually viscosity (resistance or thickness of the fluid), can't be used to relate shear stress and strain rate together. To add complexity, this effect can even vary with time. The large molecules of the honey form links with each other that have an elasticity to them and can actually counteract for a while forces like gravity. Eventually, the flow overcomes this resistance and links will break. Other links will form and this non-linear effect will persist.
I'm going to keep looking for different types of honey when I travel and I won't expect it to come out of the jar easily.
Friday, September 10, 2010
Making Blue - part 2
Further to my last post, another synthesized blue lurks in my paint box – Prussian Blue. It is a complex dark blue pigment that was first synthesized around 1706 by the paint maker Diesbach (whose first name I couldn't find) in Berlin. Since its discovery, Prussian Blue has been used extensively in making paint, and is the traditional "blue" in blueprints. Strangely, It has been used as an antidote for certain kinds of heavy metal poisoning – perhaps a story for another day.
The synthetic Prussian Blue filled a gap left by the loss of knowledge of how to make Egyptian Blue. It is a stable and relatively light-fast blue that is cheaper than ultramarine made from lapis lazuli. Artists were waiting for a pigment like this, so within two years of it's discovery it was already being traded across Europe. Prussian Blue is a strong colour that tends towards black or dark purple when mixed into oil paints. Interestingly, the particle size of the pigment creates the exact hue.
Prussian Blue is a complex chemical including iron and cyanide. It's not particularly toxic because the cyanide is bound tightly to the iron. I was surprised to learn about the number of applications where this pigment is used. In medicine, Prussian Blue is used to detect iron in biopsies like bone marrow. It is also the basis for laundry bluing, that is, it's used to add a slight hint of blue to someone's washing to combat yellowing of whites.
Once children's crayons contained a Prussian Blue, but now that has been changed to Midnight Blue. It has been a long time since I've looked at crayon colours – I think the last time was when I melted them to colour wax for candle making.
The synthetic Prussian Blue filled a gap left by the loss of knowledge of how to make Egyptian Blue. It is a stable and relatively light-fast blue that is cheaper than ultramarine made from lapis lazuli. Artists were waiting for a pigment like this, so within two years of it's discovery it was already being traded across Europe. Prussian Blue is a strong colour that tends towards black or dark purple when mixed into oil paints. Interestingly, the particle size of the pigment creates the exact hue.
Prussian Blue is a complex chemical including iron and cyanide. It's not particularly toxic because the cyanide is bound tightly to the iron. I was surprised to learn about the number of applications where this pigment is used. In medicine, Prussian Blue is used to detect iron in biopsies like bone marrow. It is also the basis for laundry bluing, that is, it's used to add a slight hint of blue to someone's washing to combat yellowing of whites.
Once children's crayons contained a Prussian Blue, but now that has been changed to Midnight Blue. It has been a long time since I've looked at crayon colours – I think the last time was when I melted them to colour wax for candle making.
Tuesday, September 7, 2010
Making Blue – or what to do if you don't have enough lapis lazuli
'Through the atmosphere the universe tones towards us in the colour blue and according to the thickness of the air, takes on every grade of blue until it goes over to black-violet on the mountain tops'
-Goethe 'Theory of Colours'
The above quote makes me think of the Van Gogh painting 'The Starry Night' – one of my favorites. I love the shades of blue (I love the swirls too but, that makes up a different story). So what makes paint blue? Typical pigments used include Azurite, Cerulean Blue, Cobalt Blue, Prussian Blue and Ultramarine which was once made from lapis lazuli.
Although there are other natural blues that can be used in pigments, lapis lazuli intrigues me the most. Years ago, I read a book on natural colours where the author journeyed to Afghanistan (in safer times) to find lapis lazuli. I don't have the book at hand, so I can't quote from it, but ever since then I've thought lapis lazuli had a fantastic story, I even like saying 'lapis lazuli'. Powdered lapis was used as eyeshadow by Cleopatra – what could be more exotic than that?
Lapis lazuli has always been prized for its intense blue color. It has been mined from Afghanistan for over 6,000 years and there are other sources around Lake Baikal in Siberia. Lapis lazuli is classified as a rock composed of more than one mineral. Since it polishes well, it can be made into jewelry, carvings, boxes, mosaics, ornaments, and vases. In ancient Egypt, lapis lazuli was favored for inclusion on amulets and ornaments such as scarabs. To answer my paint question, lapis lazuli was also ground and processed to make the pigment ultramarine.
So what if lapis lazuli wasn't available (or too expensive)? Before modern synthetic colours became available there were several options.
Egyptian Blue is a pigment that was made and used by Egyptians for thousands of years and may even be the first synthetic pigment. In Egyptian it's called 'hsbd-iryt', which translates to 'artificial lapis lazuli'. Although it's only one of many components, copper is what makes Egyptian Blue blue. The exact hue of blue can range from light to dark depending on how it is made. Egyptian Blue coloured stone, wood, plaster, papyrus, and canvas. It was also used in objects like cylinder seals, beads, scarabs, inlays, pots and statuettes. Unfortunately, when the Roman era ended, knowledge on how to make Egyptian Blue was lost. Egyptian blue has been found on objects from all over the Roman Empire and may have been independently discovered in places like ancient China.
At least 2,000 years ago a synthetic blue turned up in China. Chinese Blue and Egyptian Blue have the same basic structure and have very similar properties. The difference is that Egyptian Blue contains calcium where Chinese Blue has barium. Was this Chinese Blue produced from knowledge of Egyptian Blue making it's way along the silk road? There are theories that lean both ways.
Another ancient blue comes from pre-columbian mesoamerica and examples are still blue today. Maya Blue is a organic-inorganic hybrid that was made by heating indigo and a fibrous clay together. This method worked so well it is an active area of research today.
Back to lapis lazuli. Lapis lazuli's use as a pigment in oil paint ended in the early 19th century when a chemically identical synthetic variety, often called French Ultramarine, became available.
-Goethe 'Theory of Colours'
The above quote makes me think of the Van Gogh painting 'The Starry Night' – one of my favorites. I love the shades of blue (I love the swirls too but, that makes up a different story). So what makes paint blue? Typical pigments used include Azurite, Cerulean Blue, Cobalt Blue, Prussian Blue and Ultramarine which was once made from lapis lazuli.
Although there are other natural blues that can be used in pigments, lapis lazuli intrigues me the most. Years ago, I read a book on natural colours where the author journeyed to Afghanistan (in safer times) to find lapis lazuli. I don't have the book at hand, so I can't quote from it, but ever since then I've thought lapis lazuli had a fantastic story, I even like saying 'lapis lazuli'. Powdered lapis was used as eyeshadow by Cleopatra – what could be more exotic than that?
Lapis lazuli has always been prized for its intense blue color. It has been mined from Afghanistan for over 6,000 years and there are other sources around Lake Baikal in Siberia. Lapis lazuli is classified as a rock composed of more than one mineral. Since it polishes well, it can be made into jewelry, carvings, boxes, mosaics, ornaments, and vases. In ancient Egypt, lapis lazuli was favored for inclusion on amulets and ornaments such as scarabs. To answer my paint question, lapis lazuli was also ground and processed to make the pigment ultramarine.
So what if lapis lazuli wasn't available (or too expensive)? Before modern synthetic colours became available there were several options.
Egyptian Blue is a pigment that was made and used by Egyptians for thousands of years and may even be the first synthetic pigment. In Egyptian it's called 'hsbd-iryt', which translates to 'artificial lapis lazuli'. Although it's only one of many components, copper is what makes Egyptian Blue blue. The exact hue of blue can range from light to dark depending on how it is made. Egyptian Blue coloured stone, wood, plaster, papyrus, and canvas. It was also used in objects like cylinder seals, beads, scarabs, inlays, pots and statuettes. Unfortunately, when the Roman era ended, knowledge on how to make Egyptian Blue was lost. Egyptian blue has been found on objects from all over the Roman Empire and may have been independently discovered in places like ancient China.
At least 2,000 years ago a synthetic blue turned up in China. Chinese Blue and Egyptian Blue have the same basic structure and have very similar properties. The difference is that Egyptian Blue contains calcium where Chinese Blue has barium. Was this Chinese Blue produced from knowledge of Egyptian Blue making it's way along the silk road? There are theories that lean both ways.
Another ancient blue comes from pre-columbian mesoamerica and examples are still blue today. Maya Blue is a organic-inorganic hybrid that was made by heating indigo and a fibrous clay together. This method worked so well it is an active area of research today.
Back to lapis lazuli. Lapis lazuli's use as a pigment in oil paint ended in the early 19th century when a chemically identical synthetic variety, often called French Ultramarine, became available.
Sunday, September 5, 2010
Origami Shrimp
In my aquarium I have a number of Amano Shrimp who keep the place clean. Amano Shrimp originate from South Eastern Asia and have clear bodies about a knuckle long with wine-red spots. They have an interesting life cycle in that they are a fresh water shrimp whose larvae require salt water to live. In the wild they must migrate up and down rivers throughout their lives. When I give my fish flake food, these shrimp always dart forward and snatch the largest flakes. They then fold up the flakes into what looks like origami shapes before munching on them. I assume they fold their food this way to make a large flake less cumbersome to move with – or perhaps they just like origami.
Origami is a Japanese art of folding paper. According to wikipedia: The goal of this art is to transform a flat sheet of material into a finished sculpture through folding and sculpting techniques, and as such the use of cuts or glue are not considered to be origami. I have a number of origami how-to books from which I could make creatures from sea stars to giraffes – I don't do a lot of folding, I just have some books.
Origami is an applied geometry that has practical applications beyond making pretty cranes. Origami folds can be planned mathematically as there are a limited number of ways a piece of paper can be folded. Computational origami extends the math to optimize folds for practical like folding an airbag for car or finding an efficient way to fold solar panels to make the journey to space.
Interesting links here and here.
Saturday, September 4, 2010
More on candles
'There is no better, there is no more open door which you can enter into the study of natural philosophy than by considering the physical phenomenon of a candle'
- Michael Faraday (1791-1867)
Faraday was a physicist and chemist, best known for his contributions in the areas of electricity and magnetism. Two units of measures are named for him: the Faraday (unit of electrical charge) and the Farad (unit of electrical capacitance). Faraday also spent time on projects such as lighthouse construction and operation, and protecting metal ship hulls from corrosion. He gave tips on the cleaning and protection of artwork. On top of these and other activities, he delivered a series of public lectures and wrote for the general public. Around 1860, Faraday gave a successful series of lectures on the chemistry and physics of flames called 'The Chemical History of a Candle', a transcript of which I stumbled upon recently.
On describing a method of making candles, he explained: 'The fat or tallow is first boiled with quick-lime and made into soap, and then the soap is decomposed by sulphuric acid, which takes away the lime, and leaves the fat rearranged as stearic acid, while a quantity of Glycern is produced at the same time ... The oil is then pressed out ... and at last you have left that substance which is melted and cast into candles'
Makes me tired just reading that! Candles can also be made by the dip method I've described before or from bees wax. In Faraday's day sperm candles were made from purified oil found within the head cavities of sperm whales and paraffin candles were made from paraffin somehow obtained from bogs in Ireland (how exactly this was done was not mentioned – I'm curious so I may look this up later).
A burning candle is a chemical reaction that turns wax and oxygen into carbon dioxide and water while letting off heat and light. Soot isn't a product of this chemical reaction, instead it is incompletely burned carbon. Once lit, how does a candle get fuel to sustain itself?
The heat of the flame melts a pool of wax. This wax is then drawn to the flame by capillary action – the wick just provides a way to get wax to flame. Capillary action is a process where liquid can rise, seemingly against the force of gravity, and it is common in the world around us. For example, the transport of fluids in plants uses capillary action. If you were to put a freshly cut celery stick into a cup of water that had purple food colouring in it, you would end up with purple celery. Capillary action occurs in thin tubes or within the weave of a candlewick as a result of inter-molecular attractive forces between the liquid and solid surrounding surfaces.
Molecules within a liquid are attracted to one another, this is called cohesion, which manifests as surface tension. Because of cohesion, the most efficient shape for a liquid is a sphere, which is why raindrops are round. When a liquid touches a solid material (like the wick) that attraction now occurs with the solid material – this is called adhesion. If adhesion is greater than cohesion the surface will curve up at the boundary like the meniscus formed when water is in a glass. Alternatively, if the adhesion is less than cohesion, then the surface will curve down. So, if the cohesion of water molecules and adhesion to a solid surface act together (which would happen in a thin space) the liquid would be drawn up – the thinner the space, the higher the liquid would rise. And that's how wax gets to the flame.
By the way, Faraday's idea of using a common thing like a candle flame to teach science is still used.
- Michael Faraday (1791-1867)
Faraday was a physicist and chemist, best known for his contributions in the areas of electricity and magnetism. Two units of measures are named for him: the Faraday (unit of electrical charge) and the Farad (unit of electrical capacitance). Faraday also spent time on projects such as lighthouse construction and operation, and protecting metal ship hulls from corrosion. He gave tips on the cleaning and protection of artwork. On top of these and other activities, he delivered a series of public lectures and wrote for the general public. Around 1860, Faraday gave a successful series of lectures on the chemistry and physics of flames called 'The Chemical History of a Candle', a transcript of which I stumbled upon recently.
On describing a method of making candles, he explained: 'The fat or tallow is first boiled with quick-lime and made into soap, and then the soap is decomposed by sulphuric acid, which takes away the lime, and leaves the fat rearranged as stearic acid, while a quantity of Glycern is produced at the same time ... The oil is then pressed out ... and at last you have left that substance which is melted and cast into candles'
Makes me tired just reading that! Candles can also be made by the dip method I've described before or from bees wax. In Faraday's day sperm candles were made from purified oil found within the head cavities of sperm whales and paraffin candles were made from paraffin somehow obtained from bogs in Ireland (how exactly this was done was not mentioned – I'm curious so I may look this up later).
A burning candle is a chemical reaction that turns wax and oxygen into carbon dioxide and water while letting off heat and light. Soot isn't a product of this chemical reaction, instead it is incompletely burned carbon. Once lit, how does a candle get fuel to sustain itself?
The heat of the flame melts a pool of wax. This wax is then drawn to the flame by capillary action – the wick just provides a way to get wax to flame. Capillary action is a process where liquid can rise, seemingly against the force of gravity, and it is common in the world around us. For example, the transport of fluids in plants uses capillary action. If you were to put a freshly cut celery stick into a cup of water that had purple food colouring in it, you would end up with purple celery. Capillary action occurs in thin tubes or within the weave of a candlewick as a result of inter-molecular attractive forces between the liquid and solid surrounding surfaces.
Molecules within a liquid are attracted to one another, this is called cohesion, which manifests as surface tension. Because of cohesion, the most efficient shape for a liquid is a sphere, which is why raindrops are round. When a liquid touches a solid material (like the wick) that attraction now occurs with the solid material – this is called adhesion. If adhesion is greater than cohesion the surface will curve up at the boundary like the meniscus formed when water is in a glass. Alternatively, if the adhesion is less than cohesion, then the surface will curve down. So, if the cohesion of water molecules and adhesion to a solid surface act together (which would happen in a thin space) the liquid would be drawn up – the thinner the space, the higher the liquid would rise. And that's how wax gets to the flame.
By the way, Faraday's idea of using a common thing like a candle flame to teach science is still used.
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