PharmChem Laboratories in California was another source for LSD analysis. In the 1970s, PharmChem carried out tests on samples sent to its facility by drug consumers themselves; a list of results obtained from 1972 to 1974 can be accessed at Erowid. In this list, 514 samples were submitted as LSD. They came in different forms: on paper or sugar cubes, in tablets, capsules, gel, or liquid, and soaked onto mushrooms. Forty-three of these samples (8.3 % ) did not test positive for LSD, or they had LSD plus another substance (PCP, amphetamine, methamphetamine, pseudoephedrine, DOM, or ergot derivatives). The other 91.7 % contained LSD with no adulterating substances: 44 samples (8.5 % ) contained LSD plus iso-LSD (an allegedly non-psychoactive isomer); 5 samples (0.9 % ) contained LSD marked as impure; for the remaining 422 samples (82.1 % ) LSD was the sole substance detected. LSD quantities were expressed in micrograms for 156 samples, with 5 µg being the minimum quantity found (although some others merely had a "trace" amount), 475 µg was the maximum quantity in a single sample, and 78.8 µg was the average quantity.