The book is arranged in two parts. The first part is a fictionalized autobiography of the couple. The second part contains detailed synthesis instructions for over 200 psychedelic compounds (most of which Shulgin personally invented), including dosages, subjective experiences, and other commentary.
Shulgin's choices of synthesis procedures in the second half of the book are themselves perhaps a small act of subversion: While the reactions are beyond the ability of people with no chemistry education, they tend to emphasize techniques that do not require difficult to obtain chemicals. Notable among these are the use of mercury-aluminum amalgam (an unusual but easy to obtain reagent) as a reducing agent and detailed suggestions on legal plant sources of important drug precursors such as safrole.
Through PiHKAL (and later, TiHKAL) Shulgin sought to ensure that his discoveries would escape the limits of professional research labs and find their way to the public; a goal consistent with his stated beliefs that psychedelic drugs can be valuable tools for self-exploration. The MDMA (ecstasy) synthesis published in PiHKAL remains one of the most common clandestine methods to this day. However, many countries saw these chemicals as dangerous and banned the major ones such as 2C-B, 2C-T-2, and 2C-T-7. In the United Kingdom, most of the drugs of PiHKAL are illegal.
In 1994, two years after the publication of PiHKAL, the United States DEA raided Shulgin's lab. Finding problems with his record keeping, the DEA requested that Shulgin turn over his DEA license (which allowed him to work with and possess otherwise illicit substances), and he was fined US$25,000 for the possession of anonymous samples which had been sent to him for quality testing. Prior to the publication of PiHKAL, during the 15 years in which Shulgin held his license, there were two unannounced reviews of the lab; both failed to find any irregularities. Richard Meyer, spokesman for DEA's San Francisco Field Division, has stated that "It is our opinion that those books are pretty much cookbooks on how to make illegal drugs. Agents tell me that in clandestine labs that they have raided, they have found copies of those books," suggesting to many that the publication of PiHKAL and the termination of Shulgin's license were related.
The "Essential Amphetamines" are what Shulgin describes as the "ten essential oils that have a three carbon chain, and each lacks only a molecule of ammonia to become an amphetamine" (PiHKAL Entry #157 TMA). The list consists of:
It should be noted that not all of these are chemicals tested in PiHKAL; some are just mentioned.