xix 



He also appears to have devoted his attention to the investigation 

 of some of the compounds of manganese, and of some other metals, , on 

 which, in 1846, he published papers. In the same year he also pub- 

 lished a paper on the occurrence of mannite in the roots of Triticum 

 repens ; and one on the analysis of poppy-oil. 



It was also whilst he was still at Gottingen, that Professor Mulder, 

 the distinguished Dutch chemist, paid a visit to Wohler at that place ; 

 and, on Wohler's recommendation, Mulder engaged Voelcker as his 

 principal assistant, who accordingly returned with him to Utrecht, 

 where he remained for some time. Dr. Yoelcker assisted Mulder in 

 his various investigations, and it was doubtless this work, and the 

 connexions into which it led him, that gave a direction to his future 

 studies and labours. 



At Utrecht, Dr. Voelcker commenced the investigation of some of 

 the albuminous compounds, and he continued the inquiry from time 

 to time for some years afterwards ; but the only record of this work 

 which has come under my notice is in papers read at the meetings of 

 the British Association for the Advancement of Science : in 1855 — 

 " On Caseine, and a Method of Determining Sulphur and Phosphorus 

 in Organic Compounds in one Operation;" and in 1857 — "On the 

 Proportion of Organic Phosphorus in Legumine." 



During Dr. Voelcker's stay at Utrecht, Professor James F. W. 

 Johnston, of Edinburgh, who was Chemist to the Agricultural 

 Chemistry Association of Scotland, afterwards incorporated with the 

 Highland and Agricultural Society of Scotland, paid a visit to Mulder, 

 and he induced Dr. Voelcker to go to Edinburgh to take charge of- 

 the laboratory of that Association. He went to Edinburgh in 

 February, 1847, and remained there until August, 1849 ; excepting 

 that from November, 1848, to February, 1849, he spent at Durham, at 

 the University of which place Johnston was Professor of Chemistry, 

 and for whom he lectured and worked in the laboratory there. 



At Edinburgh the whole responsibility of the position, both as 

 analyst and consulting chemist, frequently devolved upon him, 

 Professor Johnston spending much of his time at Durham, or being 

 otherwise engaged. It was under these circumstances that he first 

 gained experience in the requirements of practical agriculture ; for it 

 was here that for the first time he found himself constantly in com- 

 munication with practical farmers, learning from them their wants, 

 and investigating and advising on the problems they brought before 

 him for his solution. Trained in analysis in the best schools of the 

 time, himself an acute observer, and having an eminently practical 

 turn of mind, the responsibility of his position greatly tended to 

 develop his powers, and to give him that self-reliance which was his 

 characteristic through life, and which, thoroughly sustained by know- 

 ledge, industry, and conscientiousness, contributed in no small degree 



d2 



