528 Arsenical Poisoning by Wall-Papers [September, 
organic matter. This is done with the objedt of causing 
the colouring-matter to adhere to the paper, muslm or 
calico, and in consequence its mischievous effedts are likely 
to be augmented, for the fabric on becoming thoroughly dry 
will be detached by rude handling ; the surface cracks, a 
the pigment is loosened, when considerable quantities ot 
arsenical dust will be set fiee# 
In the case of a wall-paper hung on the walls of a room 
every increase of temperature will liberate a quant ty ■ of the 
surface-dust, which settles on the furniture ; 01 the arse- 
nious acid which is of an extremely volatile nature, may be 
changed into hydrogen arsenide and diffused by every move- 
2 of the air. But I am reminded by an objecftor that 
the quantity of dust thrown off under any circumstances is 
far too small to produce the dangerous and disagreeable effedt 
in the human economy such as I have spoken of. I > 
at least, is a hasty conclusion to jump to. Professor I ay 01 
found that from each square foot of an arsenical wall-papei 
he could obtain from fourteen to seventeen grains of aisenic, 
and that from some flock-papers he adtually obtained 
much as fifty-nine per cent of arsenic. Other chemists have 
succeeded in eliminating a quantity of hydrogen arsenide 
from wall-papers, and have in fadt obtained from each cubic 
inch of gas one grain of arsenic. Dr. Fleck of Dresden, re- 
peating his experiments, satisfied himself that the element 
of greatest danger is found in the evolution of this gas by 
the^ joint adtion of heat, moisture, and the organic matte 
used in printing and hanging the paper. Pi° essoi S • 
Roscoe takes a similar view ; and Dr. Hambei^, of Stoc 
holm, who was himself a sufferer from arsenical wa -papei 
poisoning, having repeated Dr. Fleck’s experiments, con- 
vinced himself that the respiration of hydrogen arsenide m a 
comparatively short time will produce symptoms of poisoning. 
Within the body this gas or dust may produce o 
poisonous compounds by decomposition of album ”J* J 
fessor Selmi discovered that a volatile arsine was foimed by 
contadt of arsenious acid and albuminous matters, and that 
the new compound formed exhibited a toxic adtion diffeiing 
from that of arsenious acid ; he further expresses his belief 
that a similar produdt may be formed from the size used 
making the wall-paper and the paste employed in fixing it 
to the wall, and if so, the moisture of the air would play an 
after important part in the formation of a poisonous material, 
arsine .* . 
• The enormous volatility of the arsenious tri-chloride necess.tates special 
prec ^preparation. The gas evolved is driven ofl a. a very low 
