8 
and guaiacum tincture, which, however, disappeared on standing. 
Blood does not lose this reaction on cooking. Fourth, blood which 
had stood in contact with alcohol for two years gave in very small 
quantity, with oil of turpentine and tincture of guaiacum, a blue 
color; the alcohol itself, however, did not give a blue color. Fifth, 
dried blood cakes from a calf, 3 years old, were rubbed up to a fine 
powder. One gram of this powder was then mixed with 400 grams 
of water and shaken a number of times. A few drops of this gave, 
with old oil of turpentine and guaiacum tincture, a blue color. Sixth, 
1 drop of solution No. 5 with 5 drops of water gave the reaction. 
Seventh, if one doubles the dilution of the last solution so that 1 drop 
contains not more than 1 part of blood in 40,000, the reaction still 
persists. With very small quantities of blood at extreme dilution it 
is necessary to wait for a few minutes before the reaction takes place. 
Since Schoenbein has found it probable that the iron in the blood 
carries the ozone of the ozone carrier to the tincture of guaiacum, 
control experiments must be made with iron preparations. Accord- 
ingly, ferric oxide and hydroxide, caput mortuum, and the basic car- 
bonate of iron were tried with negative results; also limatura ferri 
(iron filings), ferrous oxide, hydroferrocyanic acid, potassium ferro- 
cyanide, and phosphate of iron did not carry ozone. On the other 
hand, ferrous sulfate, ferric lactate, ferrous iodide, and ferrous sulfide 
did blue guaiacum, but not to a very high degree; and ferric acetate, 
citrate, and chloride did blue it to a very high degree. These, how- 
ever, did not approach old putrid blood in activity. Subacetate 
of copper and copper sulfate were also recognized as ozone carriers, 
but not in very high degree. On the other hand, red lead- and anti- 
mony preparations gave negative results, as did also the red coloring 
matters, logwood, brazil wood, santal wood, and carmine. Of the 
iron preparations which are ozone carriers, none have a color similar 
to blood, so that no confusion could arise; ferric acetate is indeed red, 
but it is much brighter in color than blood. It also happens that by 
means of ammonia water we can very easily distinguish between 
liquids containing blood and those containing iron preparations. The 
former give a greenish-yellow liquid, while the latter give a strong red 
turbidity and soon produce a red precipitate. A very small amount 
of iron also gives a yellow-colored solution, which, however, is bright 
and clear, while the blood gives a fluid which is never transparent. 
One must not employ too much ammonia water in making this test. 
Only by sulphur atum ferri (ferrous sulfide) was this distinction 
between fresh blood and iron salts not so evident. After a few hours, 
however, and especially after a few days, the difference became ob- 
servable. The confusion of the blood reaction with the copper reac- 
tion is prevented by potassium ferrocyanide. Finally, old blood 
