196 A. B. MACALLUM. 
Bunge’s fluid extracts very little or no iron from sections when 
the temperature is below 20°C., but at the higher temperatures 
stated the extraction is complete at the end of the intervals 
mentioned, and with a longer action more or less of the 
“masked” iron is liberated and removed. When a tissue— 
as, for example, that of the spleen in some animals—contains 
an excess of iron in an inorganic form, the time of extraction 
must be prolonged, and the extracting fluid large in quantity, 
After the inorganic and albuminate iron has been thus removed 
from a section—a result which may be demonstrated by 
treatment of the preparation with ammonium sulphide,—it 
may be subjected to the action of either of the two other acid 
alcohols to liberate that portion of the “ masked” iron as yet 
unaffected. 
The acid alcohols do not readily attack and liberate the iron 
of hemoglobin and hematin except at a high temperature. 
Of this fact I have convinced myself by numerous experiments 
on hemoglobin, whether prepared from alcohol material or 
from that coagulated by heat. A quantity of it, in a powdered 
form, put into a flask and covered with a quantity of Bunge’s 
fluid, was heated for twenty minutes, and the fluid then, after 
filtration through a filter free from iron, was neutralised and 
treated with ammonium sulphide. The mixture gave no imme- 
diate evidence of the presence of iron, but when the test-tube 
containing it was put aside for twenty-four hours, a dark-green 
sediment made its appearance, and this was shown to be sul- 
phide of iron when it was separated on an iron-free filter and 
treated with a quantity of an acid ferrocyanide mixture. This 
iron was, in great part, derived from the hemoglobin and 
hematin, as well as from organic combinations present in the 
leucocytes and plasma, and but little had its source in the in- 
organic and albuminate compounds of the same, a fact shown 
by further experiments on the powder which had once been 
acted upon by boiling Bunge’s fluid. The extract made with 
a fresh quantity of the reagent gave, on neutralisation and on 
the addition of ammonium sulphide, the same evidence of the 
presence of iron that was obtained in the first experiment. A 
