S34? Experiments on the Composition of 
ted to the public, for making a certain kind of artificial 
slate or stone paper, which may be procured at a small 
expense, and can be employed instead of common slate, 
was announced and highly extolled a few years ago in 
several of the public journals. This substance was said 
to have a great resemblance to milled or paste-board ; to 
be of an iron-red, white, or yellow colour; to be very 
hard and stiff, but somewhat elastic; to be subject to no 
alteration even when immersed in cold water for several 
months, or when boiled for several hours; to be hardened 
by exposure to the air ; to resist fire a long time, and to 
bum slowly, after having experienced a great degree 
of heat, but, when left to itself, to become soon extin- 
guished. 
It is evident, therefore, that this paper may be applied 
to various economical purposes, such as sheathing ships, 
which it would not only preserve from rottenness, but 
also from being destroyed by worms ; for guarding from 
fire the cooking places in ships and powder magazines, 
and, lastly, for covering houses and wooden buildings. 
To this it may be added, that plates of this paper fixed 
on with brass nails, and done over at the joinings with 
cement, might be covered with some oil varnish in such 
a manner as to be altogether impenetrable to moisture. 
We are told also that a small building constructed of 
wood at Carlscrona, and cased over with stone paper, 
after being filled with combustibles and set on fire, re- 
sisted the effects of the flames and remained unhurt, and 
that the same experiment repeated at Berlin on a smaller 
building was attended with the same result. One great 
advantage of this stone paper also is, that it is exceed- 
ingly light, and may in general be procured at a cheaper 
rate than any other materials for covering roofs, as a plate 
of it twenty-three inches in length and fourteen inches 
