What were the pills....

That Bernard's friend was giving to him in the library?? I know he said they were aspirin, but the "goofiness" that Bernard got off of them almost immediately after taking them leads me to believe that they were of psychotropic nature. I know back in the day LSD only came in liquid/paper blotter form, so what the HELL were THOSE pills??? The infamous "STP?" Or what?

Any information would be greatly appreciated. Thanks :)