Use 1/2 mole of sulfuric acid per mole of mescaline so that you produce the "neutral" sulfate not the acid sulfate. Best is to measure the pH during neutralization. I would guess the correct pH to be about 7, does anyone have a better value?
From the Merck Index:
5965. Mescaline.
3,4,5-Trimethoxybenzeneethanamine; 3,4,5-trimethoxyphenethylamine; mezcaline. C11H17NO3; mol wt 211.26. C 62.54%, H 8.11%, N 6.63%, O 22.72%.
Psychotomimetic alkaloid isolated from peyote (mescal buttons), the flowering heads of Lophophora williamsii(Lemaire) Coult., Cactaceae. Isoln: A. Heffter, Ber. 29, 221 (1896). Structure and synthesis: E. Spth, Monatsh. 40, 129 (1919); K. H. Slotta, H. Heller, Ber. 63, 3029 (1930); E. Spth, F. Becke, Monatsh. 66, 327 (1935); M. U. Tsao, J. Am. Chem. Soc. 73, 5495 (1951); K. Banholzer et al., Helv. Chim. Acta 35, 1577 (1952). Novel synthesis: M. N. Aboul-Enein, A. I. Eid, Acta Pharm. Suec. 16, 267 (1979). MS determn: S. P. Jindal, T. Lutz, Eur. J. Mass Spectrom. Biochem. Med. Environ. Res. 2, 117 (1982).
Pharmacokinetics in rabbits: C. Van Peteghem et al., Eur. J. Drug Metab. Pharmacokinet. 7, 1 (1982). Mode of action study: M. E. Trulson et al., Eur. J. Pharmacol. 96, 151 (1983). Use in evaluating serotonin S2 antagonists: C. J. E. Niemegeers et al., Drug Dev. Res. 3, 123 (1983). Evaluation of use with chlorpromazine, q.v., in various psychoses: H. C. B. Denber, S. Merlis: J. Nerv. Ment. Dis. 122, 463 (1955). Toxicity data: L. B. Speck, J. Pharmacol. Exp. Ther. 119, 78 (1957); H. F. Hardman et al., Toxicol. Appl. Pharmacol. 25, 299 (1973). Reviews: A. R. Patel, Progress in Drug Research vol. 11, E. Jucker, Ed. (Birkhauser Verlag, Basel, 1968) pp 11-47; G. J. Kapadia, M. B. E. Fayez, J. Pharm. Sci. 59, 1699-1727 (1970).
Crystals, mp 35-36 deg. bp12 180 deg. Moderately sol in water; sol in alcohol, chloroform, benzene. Practically insol in ether, petr ether. Takes up CO2 from the air and forms a crystalline carbonate. LD50 i.p. in rats: 370 mg/kg (Speck).
Caution: This is a controlled substance (hallucinogen) listed in the U.S. Code of Federal Regulations, Title 21 Part 1308.11 (1995).
Hydrochloride, C11H17NO3.HCl, needles, mp 181 deg. Sol in water, alcohol. LD50 in mice, rats, guinea pigs (mg/kg): 212, 132, 328 i.p. (Hardman).
Sulfate dihydrate, (C11H17NO3)2.H2SO4.2H2O, prisms, mp 183-186 deg. Sol in hot water, methanol; sparingly sol in cold water, ethanol.
Acid sulfate, C11H17NO3.H2SO4, crystals, mp 158 deg.
N-Benzoylmescaline, needles from aq alc, mp 121 deg. Very sol in alcohol, ether.
N-Methylmescaline, occurs naturally, bp 130-140 deg.
N-Acetylmescaline, occurs naturally, mp 94 deg.