the Sivetltfb Sfctoe Paper. 163 



fragments of the different fpecimens of the ftone paper, ex- 

 pofed to the fame heat, were in fuch a ftate of ignition that 

 they hifled when immerfed in water. I however examined 

 them with great attention. The fragment _of the Swcdifh 

 manufacture was fomewhat hlack on the furface, and puffed 

 up into fmall blifters ; but did not feem to have burnt, or 

 to have changed its form. The fpecimens prepared with, 

 the fulphat, being more fpongy at the edges, burnt; but fo 

 (lowly, that in thofe of the worft quality the fourth part was; 

 fcarcely confumed in the above time. All the reft, inferior 

 in nothing to the Swedifli fpecimen, refilled the fire with 

 equal ftrength ; fo that moft of them were only a little 

 blackifti on the furface, and entirely free from blifters; nor 

 did there appear any difference that could be afcribed to the 

 glue or linfeed oil employed, as they were all of the fame 

 confidence, and none of them feemed to have been warped 

 by the heat. 



I then put fome of the fame fragments toafted in the fire 

 on a red-hot plate of iron, and immediately expofed them for 

 fifteen minutes to a ftrong heat in the middle of a furnace. 

 The Swedifli fpecimen burnt, and for five minutes emitted a 

 thick fmoke; then appeared of a white heat for fomc time, 

 and at the end of fifteen minutes was converted into three 

 friable cineritious laminae. 7 he fpecimen produced by my 

 firft experiment burnt in the courfe of a minute, kept up a 

 flame for three minutes, and in fifteen minutes was con- 

 verted into a black plate fufficiently hard. Specimens of 

 the fecond, third and fourth experiments exhibited the fame 

 appearances. A plate produced by the fifth experiment 

 was fooner deftroyed by the fire, and appeared friable like 

 the Swedifli. A plate of the fixth experiment, which before 

 had been fcarcely changed by the fire, bore the laft expofure 

 t-xccedingly well; was fcarcely changed in its form and 

 magnitude, continued fufficiently hard, and was only ren- 

 dered black and as it were fcorched. A fpecimen of the 

 leveuth experiment burnt for a whole miflute, a»d became 

 Ma blask 



