The spiritual uses of alchemical symbols are esoteric, but the basic energies they represent will provide you with different benefits. The four elements of water, earth, air and fire are straightforward but some symbols such as sulfur, creation, mercury, or salt can have other effects like cleansing or adding on to your base energy. Some have obvious uses like gold for wealth or earth for grounding. Some symbols may even be invoked to treat certain health conditions, like the symbol of iron being used to treat anemia over time.
To add the symbols to your body, it is recommended to use eye liner or body-safe markers approved for usage. It is not the same as drawing the sigil of a deity so nothing is summoned besides the energy of whatever substance the symbol represents. You can tattoo it, but you should make sure first that the energy of the substance resonates with you on a spiritual level and that you can handle having it permanently. You may also end up changing relationships with other people or the manifestations of your life since the addition of another element into your auric field will change the soul’s journey and can manifest in different ways.