I have had two types of powder lately...
1. fine white smooth powder
2. clumpy almost damp looking off white stuff
When tested the first one bubbled and turned black the instant the tester touched it.
The second one took a bit longer went purple then black in maybe 10 seconds or so.
My experience with both was that the first was much much better than the second. But part of that was the first came on a lot quicker and a lot stronger than the second.
Both were good and I know of other that have had the second type and had it react to the tester a lot better so I might have just got some lower quality.
My issue was that the last lot I bought as caps and they were not very full, and in my opinion not strong enough. What I have done is open a couple and made up a much stronger cap to give me some fun for when I have had my 4-6 weeks off.
BT definately good point, everyone needs to be careful of this.
Have fun! And remember pure MDMA can be quite different than pills, I have known people to almost not be aware it was having any direct effect due to the smoothness and lack of anything in it to knock you around (was going to say smack you out for fun, but that would be just silly
).