Go get the latest edition of Michael Moore's Materia Medica from his WWW site: http://www.swsbm.com.
Go for the manuals.
A question on the herblist in November 97:
>Hi All, when it says on a bottle of tincture that the herb to menstruum ratio is (say) 1:5, is this by weight? volume? and then if it is (say) 60% alcohol, 40% water, does this mean that the 5 in the ratio is made up of 60% alcohol and 40% water?
>Also, how do you personally decide how much dried herb to put in that canning jar before you add the vodka? I've recently been thinking that I have probably been putting too much dried herb in, since in most jars it doesn't have an easy time sloshing around.
A specification of 1:5 60% is most probably for dried herb. Weight the herb - let's say it's 100 g. The menstruum is by volume; metric is easier (for me)(1 g water = 1 ml), so to get 5 parts of menstruum you add 500 ml (= 1/2 liter) 60 % alcohol to the 100 g of herb. With dried herb you can either macerate or percolate. Maceration is the normal 'put herb in a jar, pour menstruum over, put lid on, leave 2-4 weeks, shake every day or two'. Percolation is faster, and actually quite easy, but the description of it is lengthy.
You'll want a reliable materia medica to get ratios and percentages for different herbs - a good one is available on Michael Moore's website at http://www.swsbm.com (go for the Manuals, go for the Materia Medica).
Fresh herbs are usually done at a ratio of 1:2 and 95 % alcohol - unless you use the 'simplers' -approach, which is to jam as much shredded herb as you can fit into a jar, cover it with 95 % alcohol, close the lid, wait a day, and top it up. Fresh herb is usually macerated.
The simplers approach doesn't give you very consistent quality from batch to batch, so most more professional herbalists stick to given ratios and menstruum strengths.