(For this story, this is how transfiguration, and the subsequent transmutation works. If you disagree, please write a story that includes how you believe it should work. I look forward to reading your story!)
Any object that is completely 'transfigured' into another object can be broken apart and the pieces will remain in the new form even after the spell that created the transfiguration ends. Objects that are not 'truly' transfigured and broken apart revert to their original form (albeit broken) when the spell fades away.
Background: In transfiguration, the target object will hold the form that it is given by the caster's magic for a certain amount of time and then revert to the original form. For example, the transfiguration of a rubber ball into a playful kitten will allow the magic user to play with a small feline for an hour or slightly longer but then the 'kitten' returns to the original form of a rubber ball. The transfiguration did not give the kitten a brain, internal organs, etc., just the outer shell with some of the behaviors the caster expects. This means that wizards are not able to transfigure food from another object because the magic user does not understand the true form of an apple, an egg, or a loaf of bread.
In 1993, two Herbology students at Hogwarts School of Wizardry and Witchcraft, made a startling discovery. The students, Neville Longbottom and Harry Potter, were third year Hufflepuffs working with Professor Pomona Sprout in the famous greenhouses at the school to increase production of certain valuable plants to provide ingredients for potions. The two boys studied the plants Foxglove (Digitalis purpurea) and Mother-in-laws Tongue (Sansevieria trifasciata) extensively. They used a muggle item to examine and document the structure of the stems, leaves, blooms, and seed pods. (The item is called a microscope and it magnifies the object for the eye to see details.)
Following the spider attacks at the beginning of the school year, the two students observed that the spiders that had been turned into water balloons, a muggle party favor, and then pierced to allow the water to run off, failed to return to their true spider form after the transfiguration spell ended but their shells, legs, and internal organs returned to their original form though scattered all along the road leading to the entrance to the castle.
Potter reports that in subsequent discussions, Longbottom suggested, "Our classmates defended the castle, but they don't truly understand water. That's why pieces and chunks of spider returned."
Working through the whole of the school year of 1993-1994, the two young wizards learned to successfully transform wooden sticks and broken crockery into verdant Foxglove (Digitalis purpurea) and Mother-in-laws Tongue plants. In multiple experiments, the two students with a group of friends aiding their research, would take the transfigured plants and cut them up into appropriately sized potion ingredients, and then wait for the transfiguration spell to end. However, after the spell ended, the carved-up plants did not return to their original form. This challenged many known theories of transfiguration. Test subjects of both plants were transfigured and left whole–these plants did return to the original form of broken limbs and crockery.
Once the 'transmutation of transfigured plants' was documented, Professor Sprout proceeded to repeat the testing with two other plants that she knew well enough to truly transfigure them. Once again, the same students were able to complete successful transmutations by knife or mortar and pestle of the important parts of the transfigured plants. Thereafter with the assistance of the school mediwitch and the potions mistress, the students tested the transmuted potion ingredients in simple potions. These tests showed the potions brewed with the transmuted ingredients were potent and would be effective. (NOTE: Beginning in August 1993, Leticia Evergreen was engaged by the school governors to teach potions at the school.)
With funding provided by an anonymous backer not associated with Hogwarts, four different potion masters were engaged in blind tests of the ingredients for potency and effectiveness of brewing for potions for heart failure, baldness, pneumonia, and rheumatism. When the potions were tested, there was no difference between the potions brewed with naturally grown ingredients and those brewed with the transmuted ingredients. Upon announcement of the discovery, additional blind tests were conducted by the ICW and the Guild of Potion Masters. Despite some protests, the Neville's Law proved to be valid. (The anonymous backer was later revealed to be Gringotts).
The initial announcement was made jointly by the ICW and International Guild of Potion Brewers, but the full paper was delayed for six weeks following the death of Longbottom for whom the law is named. Finally published on 15 May 1994, the paper was well received everywhere but Magical Britain. The British Ministry for Magic issued press releases that discounted the facts and theories discussed within the paper.
However, the Guild and the ICW issued a rebuttal that was carried on the front page of all British publications on 1 June. The newspaper published the rebuttal on page 2 for each of the next ten days. The rebuttal appeared again on the inside of the July issues of magazines. Other events swept the opposition to acceptance of Neville's Law in Magical Britain away early in August 1994.
In the closing paragraph of the paper released after Longbottom's death, Harry Potter wrote, 'When my friend Neville Longbottom wished himself dead, the Longbottom family lost a true scion who would have upheld their traditions for his whole life. And we lost a wizard who might have changed the entire world. I miss my friend.'
Here ends Neville's Law of Transmutation and Transfiguration. Thanks for reading and I hope to read your stories on .
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