Bring the water to a low boil.Slowly add the cannabis, stirring frequently.Next, add the sugar, stirring to dissolve.Cook for 20 minutes, covered, not allowing the mixture to boil too vigorously.Remove cover and add glycerin.Continue cooking, gentle bubbles, for 7-8 minutes, stirring constantly. The mixture will thicken.Allow the syrup to cool and transfer to a measuring cup with a spout. (Less spills!)Strain the syrup through a small strainer and cheesecloth. Best kept in the fridge.