Scientific American Supplement, No. 455, September 20, 1884 | Page 4

Ethine (C{2}H{2}) | 25.94 | 14.53 |
377.07 | 0.8985 | Propine (C{3}H{4}) | 39.91 | 9.44 | 377.07 | 1.3824 |
Butine (C{4}H{6}) | 53.88 | 6.98 | 377.07 | 1.8662 | Quintone

(C{5}H{6}) | 65.85 | 5.72 | 377.07 | 2.2809 | Benzene (C{6}H{6}) |
77.82 | 4.84 | 377.07 | 2.6955 | Styrolene (C{8}H{8}) | 103.75 | 3.63 |
377.07 | 3.5936 | Naphtalene (C{10}H{8}) | 127.70 | 2.95 | 377.07 |
4.4232 | Turpentine (C{10}H{16}) | 135.70 | 2.77 | 377.07 | 4.7003 |
Dry air | 28.87 | 13.06 | -- | 1.0000 |
* * * * *

EMERALD-GREEN: ITS PROPERTIES AND MANUFACTURE.[1]
[Footnote 1: This substance is also known by the name Schweinfurt
green.]
By ROBERT GALLOWAY, M.R.I.A.
The poisonous effects of wall-paper stained with emerald-green
(aceto-arsenite of copper) appears to be a very favorite topic in many
journals; it is continually reappearing in one form or another in
different publications, especially medical ones; there has recently
appeared a short reference to it under the title, "The Poisonous Effect
of Wall-paper." As some years ago I became practically acquainted
with its properties and manufacture, a few observations on these
subjects may not be without interest.
In the paragraph referred to, it is stated that the poisonous effect of this
pigment cannot be entirely due to its mere mechanical detachment from
the paper. This writer therefore attributes the poisonous effects to the
formation of the hydrogen compound of arsenic, viz., arseniureted
hydrogen (AsH{3}); the hydrogen, for the formation of this compound,
being generated, the writer thinks probable, "by the joint action of
moisture and organic matters, viz., of substances used in fixing to walls
papers impregnated with arsenic." In some of our chemical manuals, Dr.
Kolbe's "Inorganic Chemistry," for example, it is also stated that
arseniureted hydrogen is formed by the fermentation of the starch-paste
employed for fastening the paper to the walls. It is perfectly obvious
that the fermentation of the starch-paste must cease after a time, and

therefore the poisonous effects of the paper must likewise cease if its
injurious effects are caused by the fermentation. I do not think that
arseniureted hydrogen could be formed under the conditions, for the
oxygen compound of arsenic is in a state of combination, and the
compound is in a dry solid state and not in solution and the affinities of
the two elements--arsenic and hydrogen--for each other are so
exceedingly weak that they cannot be made to unite directly except
they are both set free at the same moment in presence of each other.
Further, for the formation of this hydrogen compound by the
fermentation of the starch, or by the growth of minute fungi, the entire
compound must be broken up, and therefore the pigment would
become discolored; but aceto-arsenite of copper
(3CuAs{2}O{4}+Cu(C{2}H{3}O{2}){2})
is a very stable compound, not readily undergoing decomposition, and
is consequently a very permanent color. It has also been not
unfrequently stated that the injurious effects of this pigment are due to
the arsenious oxide volatilizing from the other constituents of the
compound. This volatilization would likewise cause a breaking up of
the entire compound, and would consequently cause a discoloration of
the paper; but the volatilization of this arsenic compound is in every
respect most improbable.
The injurious effects, if any, of this pigment must therefore be due to
its mechanical detachment from the paper; but has it ever been
conclusively proved that persons who inhabit rooms the wall-paper of
which is stained with emerald-green suffer from arsenical poisoning? If
it does occur, then the effects of what may be termed homoeopathic
doses of this substance are totally different from the effects which arise
from larger doses. During the packing of this substance in its dry state
in the factory, clouds of its dust ascend in the air, and during the time I
had to do with its manufacture I never heard that any of the factory
hands suffered, nor did I suffer, from arsenical poisoning. If there is
any abrasion of the skin the dust produces a sore, and also the delicate
lining of the nostrils is apt to be affected. It is in this way it acts in large
doses; I am therefore very skeptical as to its supposed poisonous effects

when wall-paper is stained with it.
Different methods are given in works on chemistry for the manufacture
of this pigment, but as they do not agree in every respect with the
method which was followed in English color factories some years ago,
it will be as well, for the full elucidation of the manufacture of this
substance, to briefly recite some of these methods before describing the
one that was, and probably is still, in use; and I will afterward describe
a method which I invented, and