Quote Originally Posted by ricardo12458 View Post
...The only problem is......a lot of the units are denominated in grains.....don't think there is a modern scale that measures so accurately....

The conversion from grains to grams is straightforward, either by formula or table. At that point, it is the exact same issue as any other small quantity measurement. You make a solution using enough of the chemical that your scale can accurately weigh it, and then use a volume of the solution that delivers the original quantity specified in the recipe. This is the reason to use drops or mls of 1% or 10% solutions.