@Andro
In Alchemy Proper, you never use sulfuric acid or any other acid anywhere. By acid the sages mean the ability of their water to volatilize stuff. You already know this.
You definitely can use it as an expression of the Acid Principle and a
'lower-level substitute' for
'our water', but it is not an
absolute necessity. Other means can be used.
Unless you work completely
'purist' and move through the density scale from there, there is a need to
'magnetize' your initial matter/body by
'opening' it so it can attract AND keep
'our water'. There are various ways to 'magnetize/open/spiritualize' matter.
Some (but not all) of these ways
may involve acids, such as in the long process with Marcasite (a sulfide), where sulfuric acid forms
naturally.
Besides, you have already mentioned that you haven't performed the work yet, so IF this is
still the case and all your info comes from reading and from a set of fixed ideas you have formed in your mind, you are in no position to preach what 'alchemy proper' is or isn't, or what 'auxiliary' means are at our disposal to kick-start the process.
Interesting to note what a combination of mild shit-storm as well as positive feedback my
admitted memory-related mistake has caused here and in PM as well
Yes, the only knowledge of chemistry is needed only in the beginning.
What particular knowledge of chemistry would that be?
Rest even a 5 yr old can do.
If he/she doesn't get distracted, as 5 year olds often do

... Also, if you have a preference for a path using high temperatures, would you allow a 5 y/o child near it?
_____________________
Addendum: As 'proof of concept', in the past I have used more 'common' expressions of the
'acid principle' to
'open' various matters/bodies and
'elevate' them, such as changing 'states' (from 'closed' to 'open', from 'fixed' to 'volatile', from polar-soluble to non-polar soluble, etc...).
To further exemplify, various 'waters' such as dew, rainwater, even a body's own 'waters' are examples of (perhaps relatively week but nevertheless efficient) expressions of the 'Acid Principle'.
Another interesting example of using the 'Acid Principle' is found
HERE.
What is often referred to as 'Our Water' (Secret Fire) can be (somewhat and quite loosely) compared with a
'dew on steroids'.
It is archetipally derived from
'Spiritus Mundi Acidus Corporeus' (Golden Chain). Aso in the Golden Chain, 'Our' Subject/Matter is similarly described as
'Spiritus Mundi Fixus Alcalicus Corporeus'.
IF we commence our work with
common (corporeal) matter(s), we
inevitably work with CHEMICALS ('Code'). Using 'Code against Code' is similar to the Hermetic Way of using 'Law against Law'. A variation of 'hacking', if you will...