230 VARIETIES AND CLARIFICATION OF HONEY. 
are sometimes burst by the solidification of the honey, and 
they are, therefore, less suitable for the preservation of 
honey than small wooden casks. In damp air the honey 
gradually undergoes a partial decomposition : liquefying 
and becoming sour. If the acid of such old honey be satu- 
rated with milk of lime, some ammonia is evolved and lac 
late of lime formed. That the honey ferments, if it be 
watery, is well known. If the same after being diluted 
with water be saturated with lime a fiocculent sediment is 
formed, which possesses the qualities of a ferment contain* 
ng caseine. 
It has been hitherto believed that all honey contains some 
free acid ; but Kohnke tested recently separated and almost 
colourless marsh-honey, from more than fifty hives, with 
litmus paper, and could not discover any acid reaction. 
But upon testing honey from bees which had been killed by 
brimstone, an acid reaction took place. 
3. Clarification. — As regards the purification of honey 
for medicinal use, there has been already so much written 
and proposed "on it, that one would scarcely believe that 
anything new could be added ; nevertheless we think that 
the following deserves notice. Kohnke prefers the method 
of purification by means of charcoal (kohle) to all other 
methods. In order, therefore, to prepare Mel depuratum, 
he takes ten parts by weight of solid honey, five parts by 
weight of water, and one part of animal charcoal (bone 
black), in pieces of the size of peas, and carefully separated 
from the fine powder. The whole is heated in a covered 
tinned copper kettle over a slow charcoal fire, at a tempera- 
ture of 144°.5 F. to 1#7° F. 
This heat is to be kept up for from twenty-four to thirty- 
six hours ; frequently stirring the mixture. At last the heat 
is to be increased until the honey begins to boil, which must 
be only allowed to continue for one or two minutes. He 
then pours the whole into an earthen vessel, and lets it 
stand for six or eight days. 
