Some of the white grounds contain, however, a proportion of white lead, and in some red papers arsenic is used to fix the dye.1 Papers containing green are as a rule very objectionable, because they are often coloured with pigments containing arsenic, mercury, copper, arsenite of copper (Scheele's green), and other deleterious substances. These fly off in the form of dust, and may poison the occupants of the room in which the paper is hung.
"Green is by no means the only dangerous colour, others are fully as harmful. Blue, mauve, red, and brown have been found to contain great quantities of arsenic. Even the delicate French greys yield it very considerably." 2
"Arsenic is often found to the extent of from 6 to 14 grains to the superficial foot of wall; and Dr. A. S. Taylor has stated that he found some deep green papers which contained from 20 to 70 grains per superficial foot."3
"The presence of arsenite of copper in a sample of such paper is readily proved by soaking it in a little ammonia, which will dissolve the arsenite of copper to a blue liquid, the presence of arsenic in which may be shown by acidifying it with a little pure hydrochloric acid and boiling with one or two strips of pure copper, which will become covered with a steel-grey coating of arsenite of copper.
"On washing the copper, drying it on filter paper, and heating it in a small tube, the arsenic will be converted into arsenious acid, which will deposit in brilliant octahedral crystals on the cool part of the tube. It is obvious that, to avoid mistakes, the ammonia, hydrochloric acid, and copper should be examined in precisely the same way, so as to render it certain that the arsenic is not derived from them." 4
2 Morris, Healthy Homes.
It is made in lengths like wall paper, and in five colours - green, drab, red, brown, and buff.
The surface is hard, and can be washed or scrubbed without injury. It is a non-conductor of heat, and very durable.
It is fixed to walls by a thick mixture of 1/3 glue to 2/3 paste. Where the wall is very damp it should receive two coats of lincrusta varnish before the material is hung - and if the weather is cold the lincrusta should be put in a warm place before it is used, as it will then hang better.1
Damp "Walls should be covered with a thin sheet of some waterproof material before the wall paper is hung.
Thin sheet lead, tinfoil, indiarubber, gutta percha, and thick brown paper have all been used for this purpose, the metals being the best but most expensive. The foil is made so thin that it may be fastened to the wall with paste.
Washable Paperhangings, made by Messrs. Wilkinson and Son, of London, are said to become as hard as stone when hung, to withstand washing, and to be non-absorbent of the contagion of infectious disorders.
Such papers would of course be better than those of the ordinary description for a sick room. The walls of hospital wards, however, are generally rendered in cemeni;, and brought to a highly polished non-absorbent surface, thus avoiding the use of paper altogether.
The points to be attended to in hanging wall papers have been mentioned in Part II.
Expensive papers require to be hung with the most skill and care. At the same time, common papers are more difficult to hang well, as they are very apt to tear with their own weight when saturated with paste.
In hanging flock or other thick papers, the paste should be applied some time before they are hung, in order that it may soak well into them.
The ceilings should be finished before the paperhanging begins.
- Wall papers are intended chiefly for ornament; they relieve the bareness of the walls, and give the room a bright cheerful appearance.
A plain white paper may sometimes be applied with advantage to ceilings, especially where, from want of stiffness in the floor above, or from some defect in the plastering, the ceiling is inclined to crack.
1 Journal of Decorative Art, March 1884.