Like many profession and skills, it takes time and work to learn, the hardest part is normally beginning to understand, and learning how much we still do not know, the more we learn the more we see there is still out there for us to learn, and how little we understand, these are skills you could spend several lifetimes studying and practicing and never learn it all.
Look into this along with your study of Hokes.
Reread why we inquarter the gold content of the alloy.
Note: what material she was working with and what reagents.
What was she dissolving and in what acid was she using and why that acid?
Why was she lowering the gold content in the alloy, Why add silver or copper to the gold?
Was she dissolving silver in nitric? Gold in nitric? or these metals in aqua regia?
Study Hokes book, ask her the questions as you study you will find yourself reading the answers to your questions.
You may have to read her book, several times to get the total picture of what she is telling you between the pages, before you can begin to see the overall picture.
Gold will not dissolve in nitric acid.
Silver will dissolve in nitric acid.
A mixture or karat alloy of gold and silver can be difficult to dissolve or even will not dissolve in nitric acid, the gold can protect the silver from the reaction of your acid.
Silver can protect gold from a chloric acid, or even aqua regia, as silver forms a chloride crust that protects your gold from the acid or reagents involved.
Educating yourself just like refining takes work, time, and patience to improve your skills.