color in water. The dark brown substance readily dissolved in ammonia,
alcohol, dilute acid, hydrochloric acid, sulphuric acid, and
decomposed in nitric acid, but did not dissolve in benzine or fat oil.
After several days' rain during the summer, a quantity of the water
was caught, evaporated, and the residue dried. Its characteristics
were similar to those above mentioned. By an experiment instituted in
water under conditions similar to the first mentioned, the dry brown
substance weighed 71 grammes. It possessed the same characteristics.
In the solution effected with water containing some aqua ammonia of
the brown substance, a white precipitate of oxalate of lime occurred
when an oxalate of ammonia solution was added, but the brown substance
remained in solution. A further precipitation of oxalate of lime was
produced by a solution of oxalic acid, but the brown organic substance
remained in solution. This organic substance being liberated from the
lime was evaporated, and left a dry, resinous, fusible brownish black
substance, which also dissolved readily in water. It will be seen from
these trials that the substance obtained from the rain water running
from a paper roof is a combination of an organic acid with lime, which
readily dissolves in water, and that also the free organic acid
combined with the lime dissolves easily in water.

The question concerning the origin of this organic substance or its
combination with lime can only be answered in one way, viz., that it
must have been washed by the rain water out of the paper. But since
such a solid substance, easily soluble in water, is contained neither
in the fresh roofing paper nor in the coal tar, the only deduction is
that it must have arisen by the decomposition of the tar, in
consequence of the operation of the oxygen. The lime comes from the
coating substance of the roof, for which tar mixed with coal pitch was
used. The latter was fused with carbonate of lime. These analyses