Disclaimer: The following is a product of my own personal interpretations of the text and lore of the game and do not represent the intentions of the developers or writers. The purpose of this article is to help those that wish to roleplay their characters with interpretations and explanations to some of the more ambiguous aspects of the game.
Perhaps the second largest departure from the science and technology of our world and Erinn's is alchemy. This aspect of the world is interesting in that it is both familiar and foreign to us. At its core, Alchemy in Erinn is the manipulation of physical quantities to induce a desired effect. Alchemy in the world of Erinn is similar to Physics and Chemistry of our world however, given the magical nature of the world of Erinn, the similarities end here and we begin a journey into another aspect of this strange, yet familiar world.
Alchemy in regards to game play is divided into two categories, Battle and Construct with Battle alchemy skills are used with the intent of harming something and Construct skills are with the intention of crafting. In universe, such a divide would actually be much more blurry that what can interpreted from just simple game mechanics. Simply put, a resident would not see Battle Alchemy Skills as a separate skill, but rather a normal mundane alchemy skill pushed to the limit in order to inflict damage to something. In the sense, the cylinder is much less of a true weapon in universe, but rather a weaponized lab instrument.
In the lore, Alchemy has a rich, but ultimately tragic history with its use and development. Many personal tragedies in the story were directly or indirectly caused by Alchemy. Alchemy and its related materials are technology that the Fomors developed. Its intended purpose was to give those without natural talent in magic and mana to be able to use magic. By using the nature materials of the world, one can forgo the use of mana to manipulate the world at large, but simply do so directly with material quantities rather than magic ones. The humans saw what a wonderful tool this was and stole the technology for their use. Like many inhabitants of Erinn, not all people have the gift or the knowledge to control mana, though brilliant, not all these minds were able to use magic well despite being knowledgeable or possessing the natural talent to understand mana. The introduction of Alchemy changed that. No matter the personal skill level and talent for magic, as long as one met the conditions to replicate a specific reaction, the effect will be occur, regardless of skill or talent. This allowed those that could not use magic, use magic. With all advancements, magic users saw this with many different views. Some saw it as a curiosity but ultimately returned to their own familiar fields, others saw it as an affront to the natural connections that magic users had with nature and the world, and some saw it as a threat to their political power. The last two were invites to tragedy. With the power struggle between Alchemy and Magic, murder and betrayal ran unopposed leading to the devastation of one city and scarring of many individuals. At present (The player's time) Alchemy and Magic are in a more or less peaceful cease fire as the tragedy at Emain Macha served as a wake up call to both sides at the violence that their infighting had brought. While both sides still show tensions and mild hostilities to each other, they try to stay out of each other way's and conduct experiments independently.
In lore, both magic and alchemy have much more expand roles beyond the skills we interact with in the game system. Magic and alchemy have applications that we have never actually performed personally as players. With magic, users of the craft can bend nature to their wills with sufficient knowledge and mana, even being able to call forth creatures from other worlds. In alchemy the feats possible are said to be able to create life itself. We will examine some of the lesser known facts about alchemy as this is an article devoted to the subject. Alchemy is actually a new technology relatively to the humans of Erinn, in fact some of the skills related to alchemy are recent inventions, the most glaring of these skills being heat buster. This skill was actually invented by the corrupt alchemists and stolen by you for use against them. Much of alchemy's crafts are actually done by baking its components in the ovens, this demonstrates that as a technology stolen from fomors, humans do not actually have a full grasp on its workings.
For familiarity and ease of recognition, we shall examine the skills in alchemy as outlined in the skill tab, namely as battle alchemy and construct alchemy. For being the more simple of the two, we will examine battle alchemy first.
The skills associated with Battle Alchemy are Water Cannon, Flame Burst, Sand Burst, Wind Blast, Shock, Heat Buster, Life Drain, and Frozen Blast. The core skills, Water Cannon, Flame burst, sand burst and Wind blaster are alchemy in its rawest form, the release of the base elements. These are basic skills that technically any person can immediately use should they pick up a cylinder and some crystals. While the game mechanic demands that increased skill ranks means better damage, in universe an untrained person armed with a cylinder and water crystals would realistically hit as hard as a trained alchemist as personal skill and talent do not affect alchemy at large. Though a trained alchemist would be better at using the skill due to knowing where to hit, aiming, recoil, etc. However, as far as the basic skills are concerned, it is like loading a gun and firing. Next we see the most complex and advanced skills. Shock, Life drain, heat Buster and Frozen blast are skills that are actually out of reach for most alchemy beginners. The in universe explanation is that these skills require a deep understanding of how to manipulate the elements to do as intended. It can surmised that skills like Life drain require constant attention and control from the user to even work. Though it is worth mentioning that one of the outliers in these skills is the skill shock. Shock originally is a magic skill, much like Fireball, and Thunder, however it is ancient magic and the only person to know how to produce it naturally is the goddess Neamhain who may or may not have taught it to Jenna. The Alchemy skill Shock is actually an approximation to the original skill used by the Partholons, though it behaves and offers the same effects. The advance skills in Battle Alchemy are performed by causing reactions in the cylinder using specific combinations of crystals and controlled reactions.
Next is the actual bread and butter of Alchemy in Erinn, the construct part. Alchemy is a science in Erinn, and knowledge produced and related to it are technologies. While we have seen that magic has many uses with our knowledge of fundamental forces in universe, Alchemy has more practical uses in Erinn than magic due to their technological levels. Alchemy alters physical quantities, and the effects are immediate and understandable. Alchemy will change iron into gold, forge a sword from daggers, even crystallize mana into a stable form for use later. While Alchemists may not know by which the exact mechanic works on, they understand the effects far more than the applications of magic, and because the knowledge is unrelated to the talent of the user, many more students of the discipline can pool their knowledge for faster progress and discoveries. This is why despite being a new-born technology in reference to magic, alchemy and its masters hold more political power than magic users do in Uladh's capital, Tara.