origin of disease by oxidising and consuming
the germs which breed it. So powerful is it that one part in five
thousand parts of flour paste, blood, &c., will for months prevent
fermentation and putrefaction, whilst a little of its vapour in the
atmosphere will preserve meat, as well as prevent it from becoming
fly-blown. Although it has, in certain impure states, a slightly
disagreeable odour, this is never such as to be in any way harmful,
whilst on the other hand it is said to act as a tonic to those connected
with its preparation and use.

The new artificial colouring matters which are continually being brought
into the market, testify to the fact that, even with the many beautiful
tints and hues which have been discovered, finality and perfection have
not yet been reached. A good deal of popular prejudice has arisen against
certain aniline dyes on account of their inferiority to many of the old
dye-stuffs in respect to their fastness, but in recent years the
manufacture of many which were under this disadvantage of looseness of
dye, has entirely ceased, whilst others have been introduced which are
quite as fast, and sometimes even faster than the natural dyes.

It is convenient to express the constituents of coal-tar, and the
distillates of those constituents, in the form of a genealogical chart,
and thus, by way of conclusion, summarise the results which we have
noticed.

COAL.
|
.----------+-----------+----+-------------------+--------+----.
| | | | | |
Water House-gas Coal-tar Ammoniacal Coke |
| liquor |
.---------+-------+---------+---------. | Sulphur
| | | | | | (sulphurreted
First Second Heavy Anthracene Pitch | hydrogen:
light light oils (green | sulphurous
oils oils (creosote oils) | acid: oil
| (crude oils) | | of vitriol)
.----+----. naphtha) | Anthracene |
| | | | | |
Ammoniacal Benzene | | Alizarin or |
liquor toluene,| | dyer's madder |
&c. | | |
|