Silk Road, the “deep web” service that allowed its users to anonymously buy and sell things like illegal drugs and weapons, was shuttered this week, leaving countless users without their usual connect.

A redditor posting from what looks like a throwaway account took to the site yesterday to issue a “PSA” about the relative purity of MDMA purchased from Silk Road versus dealers in New York. Using a purity testing kit, the redditor examined samples from Silk Road and two different NYC suppliers, and found that while the Silk Road molly was relatively pure, the street stuff seemed to contain amphetamines or methamphetamines. The yellow dots above are the NYC molly, post-testing, and the black dot is the stuff from Silk Road.

From Reddit:

This is a picture I took on Saturday of 3 different samples. The two yellow samples are from two different suppliers in New York, the black sample is from a trusted supplier on silk road. Not encouraging drug use or anything, but if you are going to do it, get a test kit or ask a friend with one to test it for you!

Obviously, this is far from a thorough, certifiably accurate or statistically significant test, but it does reinforce an important point: if you’re going to be taking drugs–no matter where you’re getting them–it pays to be sure you know what you have before putting it in your body.