thiotoluidine; followed by primuline, discovered by A. G. Green in
1887.

1886. Secondary azo-dyes of stilbene series introduced by Leonhardt & Co.

ADDENDUM.

By passing steam over red-hot carbon, a mixture of carbon monoxide and
hydrogen is formed. This mixture of inflammable gases is known as
"water-gas," and in the preparation of the gas on a large scale, coke is
used as a source of carbon. If, therefore, water-gas became generally
used, another use for coke would be added to those already referred to (p.
47).

With reference to the consumption of coal in London (p. 46), it appears
from the Report of a Committee of the Corporation of London, issued at the
end of 1890, that the present rate of consumption in the Metropolis is
9,709,000 tons per annum. This corresponds to 26,600 tons per diem. It has
been proved by experiment, that when coal is burnt in an open grate, from
one to three per cent. of the coal escapes in the form of unburnt solid
particles, or "soot," and about 10 per cent. is lost in the form of
volatile compounds of carbon. It has been estimated that the total amount
of coal annually wasted by imperfect combustion in this country is
45,000,000 tons, corresponding to about L12,000,000, taking the value of
coal at the pit's mouth. Taking the unconsumed solid particles at the very
lowest estimate of 1 per cent., it will be seen that, in London alone, we
are sending forth carbonaceous and tarry matter into the atmosphere at the
rate of about 266 tons daily; and volatile carbon compounds at the daily
rate of 2660 tons (see p. 32). At the price of coal in London this means
that, in solid combustibles alone, we are absolutely squandering about
L10,000 annually, to say nothing of the damage caused by the presence of
this sooty pall. Such facts as these require no comment; they speak for
themselves in sombre gloom, and in the sickliness of our town
vegetation--they give a new meaning to the term "in darkest London," and
they plead eloquently for science and legislation to show us "the way
out."

INDEX.

Accum, condensation of tar-oils, 69

Acetic acid, 64

Acetophenone, 178

Acid brown, 151

Acid greens, 106

Acid magenta, 92

Acid naphthol yellow, 143

Acid yellow, 120

Acridine, 180

Air, composition of, 24

Albo-carbon light, 140

Alizarin black, 172

Alizarin blue, 174

Alizarin carmine, 174

Alizarin green, 174

A