We have frequently remarked small radiant and arborescent
crystallizations on dirty windows in London, and have found them to
consist of _sulphate of ammonia_. This salt, or at least, sulphite of
ammonia (which becomes sulphate by exposure to air), is an abundant
product of the combustion of coal.

_Brande's Journal._

* * * * *


_Indigo._


This valuable plant, which gives rise to as great speculation in India,
as hops in England, is much injured by wet weather; although the
rapidity of the growth of plants during much rain, in the temperature of
the tropics, is extraordinary, yet a proportional deficiency in all that
characterizes the vegetable world necessarily follows. This we find to
be the case with all forced vegetables; and the mildness of the radish
of hastened growth, when contrasted with the highly pungent and almost
acrid flavour of the slowly and gradually advanced one, may be adduced
as explanatory of this observation. Hence, it is practically well known
to manufacturers, that the indigo plant, however fine and luxuriant, as
is the natural result of much rain, is very deficient _in produce_, and
a similar loss is experienced even if the plant, without the fall of too
much rain, has grown up under cloudy weather. Sunshine, much and
continued sunshine, is essentially necessary for the proper exercise of
those secretory organs by which this peculiar drug is formed and
perfected.