The late Dr. Voelcker. 
313 
the discharge of his Hospital duties, and died after a very short 
illness. His loss, especially under these painful circumstances, 
was always most keenly felt by his father. 
In 1855, Professor Voelcker was appointed Consulting 
Chemist to the Bath and West of England Agricultural So- 
ciety ; and he held the office up to the time of his death, a 
period of nearly thirty years. In this capacity he gave lectures 
at various places from time to time, instituted field and other 
experiments, conducted much laboratory investigation, and 
contributed papers to the ' Journal ' of the Society. 
In 1852 his first paper in the 'Journal of the Royal Agri- 
cultural Society of England ' appeared. He also contributed 
one in 1855, one in 1856, and one in 1857. In that year, 
1857, he was appointed Consulting Chemist to the Society ; 
and from that time to the date of his death, about twenty-seven 
years, he contributed one or more papers to every half-yearly 
number of the Society's ' Journal.' 
For about six years after his appointment as Consulting 
Chemist to the Society, he still retained his Professorship at 
Cirencester ; and he availed himself of the opportunities which 
the College farm afforded, for carrying out various experiments, 
at the homestead and in the field, which were supplemented by 
collateral laboratory investigations. He had already com- 
menced an investigation into the composition of farmyard- 
manure, and as to the changes it undergoes in keeping under 
various circumstances ; and this enquiry he continued and ex- 
tended from time to time. Thus, he took up the question of 
the composition of the drainings from dung-heaps, and of the 
loss of manure involved ; also of the changes which liquid 
manure undergoes in contact with different soils of known 
composition, of which he made and published the analyses. 
From the results obtained in these enquiries, he was led to 
investigate the absorptive powers of the different soils of known 
composition ; — for ammonia, from its solutions as caustic 
ammonia, carbonate, and sulphate of ammonia, and as chloride 
of ammonium ; — their absorptive power for potash, from its 
solutions as hydrate, carbonate, sulphate, and nitrate, and also 
as chloride of potassium ; — ^their absorptive power for soda, 
from its various combinations, and so on. And, following up 
the same line of enquiry, he determined the changes which 
soluble phosphates undergo when in contact with different soils. 
He conclusively proved the absorption of ammonia by soils, 
by recovering some of that which had been taken up, by 
washing it out again with large quantities of water. But 
subsequent results of his own and others, showing how readily 
ammonia is oxidated into nitrates in the soil, would doubtless 
