Under the Alchemy Tab, you need to look in Alchemical Metallurgy to unlock Artifice.
Under Alchemical Metallurgy you will be given a Recipe for Alchemical Brass Ingots. These are simple to create. All they need is 5 Instrumentum and then add an iron ingot into the Crucible. This can be done easily with a stone Shovel. Once you have made your first ingot you can complete the section and leave the next section, as there are 5 parts to Alchemical Metallurgy in total. You just need to make one ingot and can leave the rest for later.