# Dictionary of National Biography, 1885-1900/Voelcker, John Christopher Augustus

​VOELCKER, JOHN CHRISTOPHER AUGUSTUS (1822–1884), agricultural chemist, was born on 24 Sept. 1822 at Frankfort-on-Main, the fifth son of Frederick Adolphus Voelcker, a merchant of that city. Ill-health during childhood postponed the commencement of his education until he was twelve years old, but by persevering energy he was able at the age of sixteen to earn his own living as a pharmacist's assistant at Frankfort. After a four years' course in that capacity he went in 1842 as manager of a similar business at Schaffhausen. In 1844 he entered the university of Göttingen, where he studied chemistry under Professor Wöhler. During his college career he also attended Justus von Liebig's lectures on agricultural chemistry at Giessen. He took his degree of doctor of philosophy at Göttingen in 1846. His earlier work was directed to researches in general mineral and organic chemistry, and he published several papers in German and Dutch scientific periodicals.
He left Göttingen to take up the post of principal assistant to Professor Gerrit Jan Mulder at Utrecht, aiding him in preparing his ‘Chemische Untersuchungen’ (Frankfort, 1852, 8vo). Mulder devoted much attention to the study of physiological chemistry, especially in its relation to vegetable and animal production. Though Voelcker's stay at Utrecht was short, his work there fixed the ultimate bent of his researches. In February 1847 he went to Edinburgh to be assistant to James Finlay Weir Johnston [q. v.], then chemist to the Agricultural Chemistry Association of Scotland. While assistant to Johnston he lectured on his behalf at Durham University, and he formed an intimate friendship with George Wilson (1818–1859) [q. v.], the regius professor of technology at Edinburgh. This friendship had a marked influence on Voelcker's subsequent career. It was during the two years he spent at Edinburgh that he first came into touch with practical farmers and gained experience of their requirements.
In August 1849 Voelcker was appointed professor of chemistry at the Royal Agricultural College, Cirencester. Here he found his opportunity. By carrying out practical field experiments, in combination with scientific work in the laboratory, he was able to put to the test matters of agricultural practice and to study their scientific import.
In 1855 Voelcker was appointed consulting chemist to the Bath and West of England Agricultural Society, and in 1857 to the Royal Agricultural Society of England. He continued to hold both positions till his death. In 1863 he resigned his professorship at Cirencester, and, coming to London established a laboratory in Salisbury Square, and commenced a private practice as consulting chemist. In 1870 he was elected a fellow of the Royal Society; he was one of ​the founders and one of the first vice-presidents of the Institute of Chemistry of Great Britain and Ireland, established in 1877. He was an active member of the London Farmers' Club, to which he contributed papers from time to time, and of which he was elected chairman in 1875. His advice was constantly sought in technical and legal inquiries, such as the questions of sewage and metropolitan water supply. He was one of the jurors of the International Exhibition of 1862, of the Fisheries Exhibition of 1883, and of the Health Exhibition of 1884.
Voelcker died on 5 Dec. 1884 at his house, 39 Argyll Road, Kensington. In 1852 he married at Frankfort Susanna Wilhelm of that city, who survived him; by her he had, with other children, two sons, John Augustus and William, who carried on his work; the former also succeeding to the posts of consulting chemist to the Royal Agricultural and Bath and West of England societies.
Voelcker's work and writings were marked by thoroughness and clearness. Though leaving no special literary work or textbook, he was a busy writer of articles of a chemico-agricultural nature in scientific periodicals, and the journals of the Royal Agricultural Society testify to his activity as an author. Every half-yearly volume contains one or more papers from his pen, the whole forming a valuable compendium of articles on the application of chemistry to practical farming. Special mention may be made of the following:
* ‘On Farmyard Manure.’
* ‘On Liquid Manure.’
* ‘On the Changes which Liquid Manure undergoes in contact with different Soils.’
* ‘On the Chemical Properties of Soils.’
* ‘On the Composition of Cheese.’
* ‘Cheese Experiments.’
* ‘On the Absorption of soluble Phosphate of Lime.’
* ‘On Milk.’
* ‘On the Absorption of Potash by Soils of known Composition.’
* ‘On the Changes which take place in the Field and Stack in Haymaking.’
* ‘On the Causes of the Benefits of Clover as a preparatory Crop for Wheat.’
* ‘On the Chemistry of Silesian Sugar-beets.’
Several of his lectures were also published.
[Private information; Biogr. Sketches by Sir J. Henry Gilbert, in Journ. Roy. Agric. Soc. of Engl. 1885, 2nd ser. xxi. 308, and by Sir T. D. Acland, Journ. Bath and West of Engl. Soc. 3rd ser. xvi. 175; Ronna's Travaux et Expériences du Dr. A. Voelcker, 8vo, Paris, 1886, 2 vols.; Bell's Weekly Messenger, 8 Dec. 1884, p. 5; Mark Lane Express, 8 Dec. 1884, p. 1548; Agric. Gaz. 8 Dec. 1884, pp. 720, 728 (with portrait), 15 Dec. p. 752; Ann. Reg. 1884, p. 168.]
E. C.-e.