Experienced mescaleros (see Mescalero and Experts) in Acateyahualco (see Meeting in Acateyahualco) gauge the quality of their product (see Mescal) by pouring the newly distilled mescal into a calabash cup and looking at the density of bubbles. I asked if this was a measure of alcohol content and was told that it was not. I was also told that if you do the same thing with commercially-produced mescal - made from Agave grown in plantations - you don't get any bubbles. Interesting. [NOTE: Image above shows mescal with "an average quantity" of bubbles. Really superior mescal would fill the cup with bubbles, I was told].