55 
perfectly neutral solution, is not able to yield with Iodide of 
Potassium and Starch the familiar blue reaction, but that this 
reaction makes its appearance when some acid or traces of 
Protosulphate of Iron are added. 
Old Spirits of Turpentine always contains some Formic 
Acid, and hence the blue color with Iodide of Potassium and 
Starch can be traced to the simultaneous presence of Acid 
and Peroxide of Hydrogen. If it could be proved that this 
reaction appears, even when the spirit contains not the slight- 
est trace of an acid, and without any addition of Protosul- 
phate of Iron, then the active agent is surely not Peroxide of 
Hydrogen. I shook Spirits of Turpentine with caustic lye 
thoroughly, whereby every trace of an acid was perfectly re- 
moved. The thus treated Spirits, showed not the slightest 
acid reaction-with wet test-paper, did not decompose Iodide 
of Potassium and Starch, and shaken with water did not 
yield Peroxide of Hydrogen; the acid as well as the active 
Oxygen was therefore thoroughly removed; the latter proba- 
bly forced to go into chemical combination with the Hydro- 
carbon and Potassa. The Spirits was then poured into a 
capacious flask, covering the bottom to a depth of about one 
half an inch, and left standing three days in common day- 
light. Then it was shaken with Iodide of Potassium and 
Starch, when a slight reaction appeared. The flask was now 
exposed for three hours in the direct sunlight, when a portion 
of the contents shaken with Iodide of Potassium and Starch; 
produced at once an intense blue color, although not the 
slightest trace of any acid could be detected. Another por- 
tion was shaken thoroughly with about one quarter its 
volume of water, which was then poured off and filtered. 
This water had a perfectly neutral reaction, and an odor of © 
Spirits of Turpentine. After addition of Iodide of Potas- 
sium and Starch, only a slight blue color made its appearance, 
but after addition of a trace of Protosulphate of Iron, an in- 
tense blue tint appeared at once. These observations show 
plainly, that (1) the active.principle in Spirits of Turpentine 
is not Peroxide of Hydrogen, and (2) that the effect upon 
