140 On the Composition of Swedish Stone Taper. 
converted into three friable cineritioiis laminae. The 
specimen produced by my first experiment burnt in the 
course of a minute, kept up a flame for three minutes, and 
in fifteen minutes was converted into a black plate suffi- 
ciently hard. Specimens of the second, third, and. fourth 
experiments exhibited the same appearances. A plate 
produced by the fifth experiment was sooner destroyed by 
the fire, and appeared friable like the Swedish. A plate 
of the sixth experiment, which before had been scarcely 
changed by the fire, bore the last exposure exceedingly 
"well ; was scarcely changed in its form and magnitude, 
continued sufficiently hard, and was only rendered black 
and as it were scorched. A specimen of the seventh ex- 
periment burnt for a whole minute, and became black and 
friable like the preceding* A specimen of the eighth 
burnt for two minutes, and then continued black and suf- 
ficiently hard. The same was the case almost with the 
ninth specimen. A specimen of the tenth, though it be- 
came black, was however scarcely changed. A frag- 
ment of the eleventh experiment burnt with a flame for 
about two minutes and was converted into ashes ; which 
was the case also with the specimen produced by the 
twelfth experiment. 
Those specimens produced by my fourth, sixth, se- 
venth, eighth, and ninth experiments, seemed to be the 
best in their external qualities and their power of with- 
standing fire and water. The same fragments suffered 
as little from the influence of the weather and atmosphere 
as the Swedish. The materials for making this article 
may be readily procured for a small price ; and the pro- 
cess is simple, and requires very little time. My speci- 
mens indeed were not so neat and elegant as the Swedish f 
but this inferiority may be obviated by practice and expe- 
rience : and even in its imperfect state the invention may 
be of great economical utility 0 
