Originally Posted by

**Ivor Joedy**
Of course I know what you mean, but I don't think the formula is complicated. It is the constant need to rethink

each case, as you demonstrate it, that is prone to failure.

The formula is so easy, especially the factor "k", that I can do most cases in my head within seconds.

Or I use it for control.

I made this formula for the simple reason that most real world cases I meet

are not of the simple type you cite.

They are closer to the following type:

Once I had 56.7 gram of a perfume, containing oakmoss, patchouli and castoreum.

Now it is only 36.47 gram. I know the concentration of oakmoss in the whole was (and is) after many dilutions 4.73%

I decide to increase it to 7.5% My oakmoss is prediluted to 66% by weight.

How much of the predilution have I to add? I like to know it within 1 minute, error free and without messing with maths.

For this I consider all other ingredients as solvent.

k = (7.5% - 4.73%) / (66% - 7.5%) = 0.0474

So I have to add 36.47g * 0.0474 = 1.729 gram of the prediluted oakmoss to obtain ca. 38.2 g perfume with 7.5% oakmoss inside.

I hope you can do it similar fast and error free with your method. And - that's important to me - without

beeing doomed to only ratios of simple numbers.

As for me, I keep the stuff as easy as possible and do not like to rethinking the same stuff every time,

once having understood the general principle. I have done the previous calculation first within 20 seconds with my

pocket calculator and without need to sit down and write something.