I'd argue that a lot of 'Alchemy' had actually been very spiritual/religious/philosophical from the start.

It was... more of a way of trying to understand the world, in a very broad, total, and inventive way, with connection to and focus on the material, but much also focused on and devoted to the divine.

The whole idea was to try and define the rules that bridged the gap, if that makes any sense.

Its not that 'Alchemy' diverged or emerged as the spiritual side of proto-Chemistry expiriments...

... its more that the materialistic parts of Alchemy that 'worked' grew out of it , into Chemistry, the 'spiritual' parts of it that 'worked', grew into Religious or Philosophical ideas, some quite popular and influential, others very, very niche.

Alchemy also isn't always related to or involving Astrology.

Sometimes those mixed.

But not always.

... and the Freemasons, other weird covert orders like that... I mean, their ideas, rituals, customs, symbolism... largely are evolutions of spritual/religious/philosophical concepts that were present in Alchemical writings.

As an example, its why most of the Founding Fathers were Deists.

They either literally were Freemasons, or, believed in the Freemasonic concept of a Deity... you actually still to this day can't be a Freemason and an Atheist/Agnostic at the same time, you must believe in a God.

The Freemasonic 'Great Work' is... to transform society into a more righteous, more divinely aligned society....according to their own conception of what that means.

The Masonic Founding Fathers literally believed that the creation of the USA ... was them doing that.

Its all over the symbolism that still exists in many of our monuments, on our currency....the all seeing eye of providence, the unfinished pyramid, "E Pluribus Unum", forging a new society by mixing together a variety of peoples, as if making a superior metal alloy.

Alchemy etymologically derives from al-kīmīā, الكیمیاء.

Which itself etymylogically has ... a couple of likely/potential meanings, possibly simultaneously.

Either:

The Black Land, referring to the fertile terrain near the Nile River.

Khemet being the Egyptian word for Egypt, the land.

Or,

Transmutation, meaning a process by which one can create or transform into or reunite with the basically Platonic Ideal form...

Or,

Metallurgy, basically.

So if you were to try and translate the term 'Alchemy' into modern English, you'd basically end up with 'The Study of Ancient Knowledge of Transformation' ... something like that.

Where you could be transforming either your soul, or literal metal, or both.

It does not help that there is the famous 'Noble Lie' from Plato's hugely influential Republic, where the idea is posited that the Gods made some people's essence out of gold, some of silver, some brass and iron... that that false idea could serve as a grand lie by which social order could be maintained.

So you've kind of got metals and souls intertwined, conceptually, going back to something like 375 BCE.

I guess what I am trying to say its that it is nearly impossible to try to describe 'Alchemy' without being anachronistic.

They did not think of things in the same way that we do today.

PS:

You wanna know arguably the most famous alchemist of all time?

Isaac Newton.

Spent by far most of his life... studying Alchemical texts.