Dissolve in alcohol, avoid water like others suggested. You can't calculate micrograms if the blotter dosage is unknown, lab testing is needed for that.
> if it's in liquid form, I'm guessing it's already in some volumetric dosing
Yes, just take a smaller dose then.
> Lab tested you say... not convenient as in I can't just go to a lab and tell them "hey I need to be trippin so can you check these blotters"?
Here in my country I can... this kind of services are available for free in some European countries.
Energy Control in Spain provides this to foreigners for a relatively small fee. You can contact them at: international AT energycontrol.org
You're right, but it's probably much easier than you think[1].
You can also send anything into ecstasydata[2] and it will be tested a posted to the site. Unfortunately under US law they can't tell you purity or dosage, but can at least tell you if it's legit.
[1] http://energycontrol.org/ [2] http://www.ecstasydata.org/view.php?id=3897
I actually have Fadiman's book but didn't get to the part of micro dosing - was more interested in the full trips guidance, but I remember being very intrigued by micro dosing.
Lab tested you say... not convenient as in I can't just go to a lab and tell them "hey I need to be trippin so can you check these blotters"?