16*5 Experiments on the Compofition of 



IX. A plate which I formed of an ounce of pulp, with 

 half an ounce of glue, three ounces of white bole, an ounce 

 of chalk, and an ounce and a half of linfeed oil, was fuperior 

 to that mentioned in the preceding experiment. This fub- 

 ftance retains figures impreffed upon it, and, tinged with 

 half a dram of Prufiian blue, aflumed ablueifh green colour. 



X. An ounce and a half of pulp, with an ounce of glue 

 and four ounces of chalk, afforded a plate exceedingly fpongy. 



XI. An ounce and a half of the fame pulp, one ounce of 

 fulphat of iron, and four ounces of white bole, without glue, 

 produced a plate yellowifh and fpongy. 



XII. An ounce and a half of pulp, four ounces of white 

 bole, with an ounce of fulphat of iron, and the fame quan- 

 tity of glue, produced a yellowifh plate a little more folid. 



I tried feveral other mixtures; but as the plates they pro- 

 duced were of an inferior quality, I (hall not give any ac- 

 count of them. The plates which had been prepared in the 

 above manner I cut into feveral pieces, and daubed over a 

 fpecimen of each with boiled linfeed oil. The parts covered 

 with the oil alTumed a darker colour, and the fuperfkies ac- 

 quired more folidity, nor were they kfs capable of refitting 

 fire. 



Being defirous of comparing the productions of my expe- 

 riments with fpecimens of the Swedifh ftone-paper, I mace- 

 fated about an inch fquare of each incojd water. After they 

 had been macerated four months, the fpecimens prepared 

 with fulphat of iron were confiderably fwelled, but thofe 

 made without linfeed oil feemed to have fcarcely fwelled at 

 all. Thofe, however, which I had daubed over with boiled 

 linfeed oil or linfeed oil varnifh, exhibited as little appear- 

 ance of change as' the Swedifh. 



I put a fquare inch of each of the different kinds upon aa 

 iron fpatula, together with alike quantity of beech wood, 

 and expofed the whole to a ftrong heat in the mouth of a 

 furnace. After fifteen minutes the wood began to bum, 

 and in fifteen minutes more was reduced to allies. The 



fragineuts 



