The late Dr. V'vekfter. 
311 
of 'The Chemistrv of Vegetable and Animal Physiology.' 
Dr. Voelcker assisted Mulder in his various investigations, and 
it was doubtless this work, and the connections into which it 
led him, that gave a direction to his future studies and labours 
— to which, in fact, his devotion to agricultural chemistry 
owed its origin and its stimulus. 
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 was 
in papers given at the Meetings of the British Association for 
the Advancement of Science ; in 185/) — " On Caseine, and a 
method of determining Sulphur and Phosphorus in Organit- 
Compounds in one operation;"' and in 1857 — "On the pro- 
portion 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. \ oelcker to go to 
Edinburgh to take charge of the laboratorv of that Association. 
He went to Edinburgh in February 1847, and remained there 
until August 1849 ; with the exception that he spent from 
November 1848 to February 1849 at Durham, at the University 
of which place Johnston was Professor of Chemistrv, 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 lor the first time he found 
himself constantly in communication 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 eminentlv 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- 
knowledge, industry, and conscientiousness, contributed in no 
small degree to his success as a teacher, a scientific adviser to 
the practical farmer, and in his Profession as a Consulting 
Chemist generally. 
During his stay in Edinburgh, he made the acquaintance of 
