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as the intrinfic ftrength of the paper is great, the lefs will it fuffer 

 under the combined feverities, of wetting, and working it, in the 

 printing, or rolling prefs. 



It would be ufeful to advert to the caufes of this fuperiority, they 

 feem to be chiefly thefe two. The peculiar ftrufture of the wheel 

 in the French machinery, which maflies, or triturates the ftuff, in 

 the vat, or receptacle. The cogs, or rather the ribs of the cylin- 

 ders, by which this operation is performed being more diftant from 

 each other, the material is cut and broken into longer filaments, 

 which, when they come to be combined in paper, wrap over, or in- 

 tertwine and embrace each other, with more flrength and tenacity, 

 forming by their length an aggregate of greater durability. 



A new caufe of ftrength, may be the rejection of fmalt, and other 

 blue materials, from the compofition of French paper. Such fubftances 

 evaporate, in procefs of time, and confequently leave, by their abfence, 

 many pores and interftices in the paper, whereby its ftrength is im- 

 paired, and it becomes daily more and more expofed, to the aftion of 

 external air, the great deftroyer of moft produftions of art. Perhaps 

 alfo there is a peculiar nicety, in the degree of trituration of the rags, 

 which hitting the medium between too much and too little, may contribute 

 to the ftrength and goodnefs of paper. To afcertain this, if poflible, 

 by experiments, and to obfcrve it in practice, ftiould be the care of 

 the attentive manufafturer. It is certain, that if trituration is continued 

 until the material becomes greafy, it is too milch. 



It is alfo a matter of great importance, to attend particularly to 

 the careful aflbrtment, of the rags, with refpeft to firmnefs and fine- 

 nefs, fo as to have the whole heap intended for each particular clafs or 

 fpecies of paper as nearly as poflible of the fame quality. 



Some of the eminent French chymifts, who have ftudied to make 

 philofophy ufeful, by a praftical application to arts and manufactures, 

 have, as I have fald, taught the ufe and importance of the muriatic 

 acid, for deterging and whitening the rags for papers. It is faid that 



late 



