>>>I have one more question if you will bear with me.
Why can't a "part" be in weight? I have seen other books use it.<<<
Wow, it seems like the harder we try to explain, the further we push you away from understanding the concept.
Let's go at this way.
The reason the "parts" can't be in "weight" is that's the way the original herbalist created the formula.
As 'wings said, this is more "art than science" (you know, the long forgotten "ART of healing"...science has failed dismally, eh?)
As I mentioned, it's like baking bread...the same specific recipe will fail or succeed on any given day depending upon the humidity in the area (and how high or low one is located geographically).
If you want to sit down with a gram scale and a Dr. Christopher/ Dr. Schulze formula, and start calculating & converting the parts to "weights", have a blast...but you'll likely end up with different RATIOS than they intended...here's why:
Let's say the formula is for 3 parts Mullein (VERY leafy and light) to 1 part Comfrey Root (VERY heavy and dense)
Those converted weight will NEVER be consistent from supplier to supplier (a cup of dried comfrey root from Mountain Rose weighs more or less than one cup from Pacific Botanicals). All herbs weigh more or less depending upon the humidity in the air...and some will absorb more water from the air that others (the leaf absorbing much more than than the root)...hence what one cup of Comfrey weighed yesterday, might only be 7/8 cups to get the same weight tomorrow (depending on humidity, etc).
But 1 cup of Comfrey root to 3 cups of Mullein leaf will ALWAYS be the correct ratio of one herb to another....no matter HOW much humidity they've absorbed or how different the weight is from supplier to supplier.
This brings up another point (which you didn't ask) but I want to clarify. Never mix powdered herbs with herbs that are c/s (cut & sifted) i.e. chopped into consistently sized pieces. A cup of powdered herbs has virtually "zero air space" but a cup of chunked herbs contains LOTS of air. To keep the ratios correct in any given formula, always use ALL powdered or ALL c/s, but never both (unless that's the only thing available, and you really need the product).