MICROCHEMICAL REACTIONS OF BARIUM 
345 
stated, no deleterious influence on the precipitation of the oxa¬ 
lates of calcium and strontium, we meet, in the case of barium, 
with a most interesting and remarkable reaction. Owing to the 
formation of double oxalates of barium and iron or barium and 
aluminum, instead of the typical fibrous bundles of needles 
and crystallites, there are now obtained tufts and bunches of 
very long exceedingly fine curving hair-like crystals (trichites) 
of characteristic appearance. The chemical composition and 
formulas of these compounds have not yet been definitely ascer¬ 
tained. 
In order to obtain this interesting compound, proceed as 
follows: To the test drop containing barium, add ferric chloride 
in sufficient amount to impart a faint but distinctly yellow color; 
then add a fragment or two of sodium or ammonium acetate; 
stir. The yellow color should now have changed to a reddish 
tint. Into this drop, thus prepared, cause a drop of oxalic acid 
to flow. Tufts and sheaves of very fine hairs soon appear. The 
hairs rapidly grow longer and longer and soon begin to curve in 
a most peculiar manner. The presence of calcium or strontium, 
or both, in even large amounts does not appear to have any 
serious influence on the formation of this double oxalate of 
barium and iron, save that its separation is often somewhat re¬ 
tarded. In such mixtures the oxalates of calcium and strontium 
first appear in their usual form, then after a time the hair-like 
tufts of the double oxalate appear. If the quantity of barium 
is quite small, in proportion to the iron, little rosettes of radiating 
needles are obtained, separating near the edges of the drop. 
Aluminum gives rise to the formation of a similar product, 
but the crystal masses are colorless, while those; of the iron salt 
are light brown. 
EXPERIMENTS. 
a. Test a salt of Ba with H2C2O4, in both hot and cold solutions. 
h. Make a mixture of Ca, Sr, Ba. Add H2C2O4. Repeat the experiment in 
HNO3 solution; after a few minutes, decant the clear solution, concentrate slightlv 
and add NaC2H302. 
c. Try the effect of the presence of FeCh on the precipitation of oxalates of Ca, 
Sr, Ba; first each element separately, then in mixtures of Ca and Ba; Sr and Ba; 
Ca, Sr and Ba. 
