"Acid" refers to one specific chemical,
lysergic acid diethylamide (LSD).
"Research chemicals" is usually a euphemism for "unscheduled drugs" and can refer to hundreds of possible chemicals. Throughout the years there's been a few psychedelics discovered that are active at the sub-milligram levels needed to be active on blotter. These are drugs like the NBOMe series (
25I-NBOMe is popular but there are also half a dozen more of varying activities - 25C, 25D, 25iP, 25P, 25B, 25E, C30-NBOMe - as well as NBOH and NBF compounds of the same.) Prior to the discovery of the 25x-NBOMe series people used to occasionally see things like
5-MeO-AMT and
DOB/
DOI. There is also (rarely) stuff like
Br-DFLY on blotters too - although generally the fancy expensive designer RC drugs are more expensive than LSD and are less often substituted.
These drugs, being much newer and lacking as much "live fire testing" as LSD has recieved throughout the years, are generally much riskier compounds to take. Stuff like the DOx and 25x-NBOMe series have caused deaths in overdoses.
Currently the biggest risk is people substituting things like 25I-NBOMe for LSD, because they both fit on blotter papers and can be taken sublingually (under the tongue). However, NBOMe compounds generally are dosed much higher than LSD on blotter & have a lower safety margin, so it means taking more than one or two tabs can be a huge risk.
A quick and dirty test is
making sure your acid blotters glow under a UV light - NBOMe compounds don't. There are also commercial LSD test kits as well as the Ehrlich reagent for indoles (which is a color spot test for LSD).
Tripping with friends has a social component that's almost as important as the biology of the psychedelics: shared hallucinations are actually more common then you'd think. My favourite shared hallucination fact is that sometimes people who get really loaded on deleriants (don't reccomend it - the experience is amnesic and unpleasant) will share invisible cigarettes. (The military observed this when developing incapactitating agents like
BZ.)