You will need to take the dried powder and boil it down for a bit longer than the fresh cactus. Just stir and stir, and stir some more for about a 1/2 hour. You'll notice the cactus start to slightly separate from the water. At this point, stop stirring and see if there is any foam that builds up. If there is no more foam, it is then safe to put the top on the pressure cooker and get the pressure up to 15psi. When using powdered cactus, let the cactus stay at 15psi for 15-20 minutes. At that point, the cactus WILL separate from liquid and allow you to continue with your next two pulls. However, this tek is way more work than is necessary for dried powder. All one really needs to do with powder is base strongly with NaOH or KOH, put in solvent, shake up and let sit for about 12-24 hours. Then just pull the top solvent layer, salt, put the solvent layer back into the extraction vessel, then repeat 3-4 more times. SWIM performs this tek by adding about 500ml of a 30% KOH solution to 100 grams of cactus powder. He shakes the crap out of the jar, then adds about a 3-4 inch layer of d-limo. Shakes vigorously a few more times, then lets the jar sit for 24 hours. He then pulls the d-limo off the top, salts and repeats another 4 times. This tek takes a bit longer, but it is probably the easiest mescaline extraction tek there is. Once SWIM gets some more powder in, he can do a writeup for that tek if anybody is interested.