l6o Evperhttffnts on the Compqfititn cf 



111 which M. Servin ohferved fome traces of martial vitriol 

 {Julphat of iron). 



Though I made a number of experiments in order to dif-> 

 cover the compofilion of this flate, I (hall here mention 

 thole only which were attended with the bed fuccefs. But, 

 to avoid repetition, I (hall firft defcribe that previous mani- 

 pulation which appeared mod convenient. 



The red or white bole, carpenter's ochre and chalk, which 

 I employed for thisufe, were reduced to a fine powder. A 

 pulpy mafs of the coarfcft kind, procured from a paper- 

 manufa£tory, after being macerated in water, was ftrongly 

 prefled and weighed out for ufe. The weight was increafed 

 about two-thirds by the moifture. In giving an account of 

 the following ' experiments, I fhall mention the weight of 

 this fubftance as alluding to it when dry. 



The glue was diflblved in a moderate quantity of water. I 

 added martial vitriol undiflblved, and employed unboiled line- 

 feed oil. 



For want of a fufiicient quantity of raw pulp, I procured, 

 for fome experiments, fragments of coarfe old paper and book- 

 binder's {havings; which, after being boiled for about three 

 hours, were much tenderer than that brought from the pa- 

 per manufactory. A pound of this when wet, after it had 

 been prefled, exceeded that which was dry by about two- 

 thirds. 



The pulp procured from a paper manufactory being mixed 

 in a mortar with the diflblved gluten, and being afterwards 

 formed into a pafte by the addition of the above earths and 

 fulphat of iron, was well beat up in the mortar, and linfeed 

 oil then poured over it. The mafs, being prepared in this, 

 manner, was fpread out with a fpatula above a {Beet of coarfe 

 paper placed on a board furnifhedwith a rim or border; ano- 

 ther (heet of the fame paper was then fpread over it, and a 

 fccqnd board was placed above all. The whole being then 

 inverted, the board with the rim was taken off, and then the 



firft 



