To complete this section you need 1 Magic Tallow. Throw an item that contains 1 Ignis into the Crucible, and then add 1 rotten flesh to get 1 Magic Tallow.
You will want to unlock the Alumentum section. This can be completed if you have the research. Alumentum lasts 3 times longer than coal.
The easier way to make Alumentum and to avoid a huge amount of Flux entering the area is:
Then using 4 charcoal as the catalyst, you will get 4 Alumentum. You can then use 2 Quartz Slivers to extract the 4 remaining Alkimia. This would eliminate any risk of flux getting into the area.
To get Magic Tallow and Alumentum, you can use 4 coal and 2 gunpowder. Then use charcoal as the catalyst. Then throw in 16 rotten flesh (one at a time as a catalyst) to get out Magic Tallow. You might run out of water but you can top up the cauldron. This should give you 20 Magic Tallow. You can then use Slivers to get out the 5 remaining Alkimia.
Make sure you add the charcoal FIRST. Even when the Crucible is empty there will still be essences in it, just add water.
Ensure you are wearing your Goggles of Revealing!
Once you have crafted your Tallow you can complete the Hedge Alchemy section.
The next stage of Hedge Alchemy will explain about Tallow Candles. These will come in handy later on, but it will also show you how to make items such as gunpowder and slime balls by putting in certain Essences into the crucible. It will also tell you how to convert rotten flesh into leather.
The easiest way to complete this section is to grab 2:
Add one of these to the crucible and add one more to get two back. Complete this part and you will be shown how you to make cobwebs, buckets of lava, clay and string by combining Essences and items in the Crucible.
You will also need to create these items in the Crucible. The easiest and safest way (with minimal flux) way to do this is:
You can then complete this section.