One of the most basic forms of Transfiguration is that of state change Transformation. A state form Transformation is defined as the Transfiguration of a substance that changes only its state of matter but not its type of matter. As this Transfiguration does not change the nature of the basic material with which the witch or wizard uses, state change Transformation is perhaps one of the simplest Transfigurations. Nevertheless, like all Transfigurations, state change Transformation requires precision and an in-depth understanding of the change the witch or wizard wishes to invoke on the substance. In this case in particular, we must thoroughly understand the states of matter.

Understanding the States of Matter

There are four known states of matter: solid, liquid, gas, and plasma. (Due to its highly energized and dangerous nature, we will not cover Transformations involving plasma.) Most of the time, these separate states can be identified by observable properties. Solids are the state of matter that retains a fixed volume and shape, regardless of what container they’re put in, provided that the container is large enough to hold the item. Liquids maintain a fixed volume, but their shape will alter to match their container. Gases expand in volume and shape to fill the entire container they occupy.

For example, in the case of water, which you are no doubt familiar with, drinking water and the water in lakes and oceans are all in a liquid state. When water freezes into ice, it has become a solid. And when you boil water, it transforms into its gaseous state. A broomstick is a solid. Pumpkin juice is a liquid. The vapor of the Draught of Peace is a gas.

Clearly, identifying separate states of matter is simple enough. However, in order to Transfigure substances from one state to another, we must understand the states of matter beyond their simple bulk properties; we must understand their molecular properties.

Two important words to remember at this point are enthalpy and entropy. Enthalpy is the total energy of a system, and entropy is the measure of chaos in that system. In regards to the states of matter, entropy and enthalpy usually correlate. For instance, the molecules in a solid are very low in energy. The molecules around them bind to them and knit closely into a patterned structure called a “crystal lattice," and because they do not have the energy to break the bonds, they do not move much. Thus, solids have low enthalpy and low entropy. Molecules of a liquid have more enthalpy; they can resist bonds from other molecules enough to slip and slide over one another, but they do not have the enthalpy or entropy of gas molecules, which ricochet off the walls of their container like a pack of crazed pixies, with no significant bonds to one another. To put it simply, solids have the least amount of enthalpy and entropy, gases have the most, and liquids are somewhere in the middle.

Changes of States of Matter

Beyond the three basic states of matter, there are six separate phase changes, which are melting, freezing, condensing, vaporizing, sublimation, and deposition (also known as desublimation). Melting is the change from solid to liquid, and freezing is the reverse. Similarly, condensing is when gas changes into a liquid, and vaporizing is when a liquid becomes a gas. Sublimation and deposition are less well-known, as they are not as common in nature as the other phase changes, but sublimation is defined as the change from solid directly to gas, whereas deposition is when a gas becomes a solid.

The changes that involve a substance moving from a more energized state of matter to a lower one are called exergonic, meaning that they expel their energy into the surrounding environment. The exergonic phase changes are freezing, condensing, and deposition. The remaining three phase changes are considered endergonic, meaning that they absorb energy from their surroundings.

In nature, substances usually shift through states of matter through either temperature or pressure changes. Low surrounding temperatures leech warmth and therefore energy from the substance, whereas high temperatures bleed energy into the substance’s molecules. High pressure causes phase changes by increasing the amount of energy necessary for molecules to resist their bonds, and low pressure does the opposite.

In state change Transformations, we will simply increase or decrease the enthalpy available to the molecules of the substance. Please note, however, that temperature change is an indicator of heightened or decreased enthalpy and is not separate from magical state change Transformations. Substances that do not change phase with simple, non-magical means likely require a very high level of enthalpy to change state, and a Transformation of such substances may bring about a dangerously drastic temperature change. As a result, Transformations of such substances (iron, for example, such as Altea the Ambitious painfully discovered in 1643) are highly discouraged.

Performing State Change Transformations:

In order to perform the Transformation, keep in mind that you are changing the level of energy of the molecules of the substance; therefore, the energy of your mental state and wand movements is extremely important in the effective use of the spell. Specifically, in order to change the substance from a state of higher enthalpy to one of lower enthalpy, you must remain calm, collected, and orderly. To change the substance to a state of higher enthalpy, you must be energetic, excitable, and spontaneous. (As a result, many students find that energy-decreasing Transformations are considerably easier during extended study periods, or after other activities that cause chronic boredom.)

Exergonic Transformations

Exergonic Transformations are used for condensation, freezing, and deposition, although deposition requires some alteration from the general spell, due to the fact that deposition involves the cross from gas to solid without ever passing through the liquid state. To decrease the enthalpy of the substance, you must first recognize the higher energy state of the substance, and visualize the energy levels to which you wish to bring it. Then, point your wand at the substance and reach your energy to match that of the molecules, as if to snag them. Move your wand in a slow horizontal line before you, moving from the outside of your body towards the inside. Your wand should be carefully controlled; this movement is not a leisurely wave, but rather, it is calculated and firm. At the same time, calm your energy and slow your wand until it comes to a steady stop. The incantation for this spell is “Cubitus." You should finish saying the incantation at the precise moment that your wand comes to a stop. Visualize that you are pulling the molecules in, and settling them to rest.

To alter this spell for deposition, recall that you are reigning in the molecules from a much more lively state than in other exergonic Transformations. The wand movement for this spell is similar to that of other exergonic transformations, but it is steadier and more dynamically changes pace before coming to a very firm stop. Rather than simply settling the molecules, this Transformation is more akin to pressing the molecules up against a brick wall. Many students have difficulty with this Transformation because they tend to try to slap the substance into submission, but the spell requires a very calm energy. Even if deposition spells are firmer than other exergonic spells, an antagonistic burst of energy is ineffective in producing a state change.

Endergonic Transformations

Endergonic Transformations refer to the magical invocation of state changes including melting, vaporizing, and sublimation, and, similar to the case of deposition in exergonic Transformations, sublimations also reserve a special case in endergonic spells. Like exergonic spells, endergonic spells require you to visualize the energy change you wish to make, but whereas exergonic transformations require you to settle your energies and use calm, precise wandwork, endergonic spells are somewhat more spontaneous. You should begin with your mind calm and steady, matching the energy of the substance, but release a burst of energy towards the end of the spell. The wand movement is an upward flick at an angle of about 80 degrees, with increasing speed then a sudden halt at the end, as if the molecules are being flung away. The incantation is "Concito" and should be said with increasing energy.

Sublimation endergonic spells are similar, but the wand movement is more pronounced; rather than a simple flick, the wand movement for sublimation Transformation is an unguided flourish that often ends with the wand tip pointed back over your shoulder. Remember, the difference between sublimation and other endergonic spells is that sublimation requires an even stronger increase in enthalpy.

CASE STUDY: Water Water is perhaps the substance that is most commonly used in state change Transformations, which, of course, is why it is a primary exception to the general freezing spells. Whereas the molecules of the vast majority of substances are closest together in their solid state, water does not follow that rule. In its solid state (ice), water molecules are actually held further apart than they are in their liquid state. They are still rigid, with little energy, but the difference in structure does have a significant difference on the spellwork for freezing Transformations of water. In particular, the wand movement of the freezing spell for water is not a short, firm line inwards across the body. Instead, it is a longer, languid horizontal line that moves outwards and comes to a much slower stop. The incantation and mental process involved in the spell remains unchanged. All other state change spells for water remain true to the general rule.