if there is a purple/dark blue tinge to the black then it is most likely MDxx. the puff of gas/smoke often happens with strong pills as well as pure powder.
Thanks,there was no purple just straight to black almost immediately with a puff of smoke, I`ve been told by a mate they are very very strong + very very lovey!!!
i guess it doesnt matter how many times i say it someone still doesnt get it... smoke and a very slow change to grey/black is an indication of DXM smoke and a quick change to purple/black (really its a very dark royal blue) is an indication of MDxx
smoke alone is not an indication of anything. you must look at the colour of the reaction. even strong amphetamine has been known to give off smoke. and by "smoke" we mean a puff of gas that looks like smoke (a chemist will probably yell at me for that one). apparently the DXM reaction gives a much darker "smoke" than an MDxx one.