Olaus, one of the most learned men of his age, the son of a Lutheran minister, was born in 1626, at Borchen in Denmark. He was sent to study physic in the university of Copenhagen in 1644, and he began to practise during a terrible plague which made great havoc in that city. In 1660, although appointed professor of botany and chemistry, he visited Holland, England, and France; was received as doctor at Angers; and visited Rome in 1665. In the course of his travels he attended the most celebrated schools, and was selected by Queen Christina as her master in chemistry. He returned to Copenhagen in 1666, and discharged the duties of his office with great assiduity, as his works abundantly testify. He was raised to the office of member of the supreme council of justice in 1686, and to that of counsellor of the royal chancery in 1689; and he died of the operation of lithotomy in 1690. The following is a list of his works:

1. Dokimasia Metallica, Copenhagen, 1660, 8vo; 2. De Ortu et Progressu Chemic Dissertatio, ibid. 1668, 4to; 3. Hermetis, Egyptianorum, et Chemicorum Sapientia, ibid. 1674, 4to; 4. Lingua Pharmacopoeiarum, ibid. 1670, 4to; 5. Cogitationes de variis Lingua Latina Ætatis, ibid. 1675, 8vo; 6. De Causis diversitatis Linguarum, ibid. 1675, 4to; 7. De Sonno et Somniferis, Francfort, 1680, 1683, 4to; 8. De Usu Plantarum Indigenarum in Medicina, Copenhagen, 1688, 1690, 8vo; 9. Dissertationes V. de Poetis Graecis et Latinis, ibid. 1676; 10. Conspectus Chemicorum Scriptorum Illustriorum, ibid. 1696, 4to; 11. De An-