Experiments on the tompofitton, &k. x$g 



mgly light, and may in general be procured at a cheaper 

 rate than any other materials for covering roofs, as a plate 

 ot it 23 inches in length and 14 inches in breadth cofts at 

 Carlfcrona only two fchellings Swedifli. 



An invention of fuch utility and importance ought there- 

 fore to excite the ingenious to attempt an imitation of it, in 

 order that, if poffible, it may be rendered more public. As 

 Toon as I obtained a fpecimen of it from Sweden, I made 

 experiments to try whether I could not difcover the method 

 of making it. The fragment which I firft examined was a 

 line m thicknefs. It was light, eafily broken, and poffeffed 

 all the properties above enumerated. As the analyfis by 

 which M. Antic de Servin, at the requeft of M. Crell, en- 

 deavoured to illuflrate the nature of this paper, did not ap- 

 pear to me fatisfaftory, I fubjefted part of the fpecimen 

 fait me to a farther examination, leaving a third portion en- 

 tire- for the fake of cemparifon. 



After this examination the red ftone-paper appeared to 

 me to confift of, 1. Martial-bole, which feemed to be equal 

 to half its weight, and which, on account of the chalk per- 

 haps, or calcareous earth with which it was mixed, pro- 

 duced a little effervefcence with acids. Perhaps alfo there 

 were fome particles of another earth, the difcovery of which 

 would be of little importance to the obje&of this refearch. 

 %. A vegetable matter of little weight, and fimilar to that 

 ufed in the making of common paper. This formed about 

 a fourth part of the weight. 3. An animal glue, fimilar to 

 that which is procured by boiling from various animal fub- 

 ftaiKcs : and, 4. A certain oil which feemed to have a refem- 

 Uance to linfecd oil. Thefe fubiianccs (3 and 4) made 

 about a fourth part of the weight. 



Another fpecimen which I received from Mr. Cameron, 

 architect to her imperial majefty, contained the fame fub- 

 ftances ,„ proportions a little different. I was, however, not 

 able to obtain fpecimens of the white and vellow ftone-paper, 



Wi 



