PAPER MAKING. oil 



disintegrated under the influence of steam of lower pressure and tempe- 

 rature, or of steam of equal pressure and temperature, applied during 

 a shorter time than when no lime is used. The quantity of lime which 

 may be employed in applying this mode to the average mixed rags of 

 commerce may, it is found advantageously, amount to 3| per cent, of 

 their weight, or thereabouts ; and this lime, made into a milk with three 

 or four times their weight of water will turn a suitable menstruum for 

 the purpose. Two hours' digestion of the rags in this liquor in an anto- 

 clave boiler, supplied with steam at a pressure corresponding to 276 

 deg. on Fah. scale will be found in ordinary cases to accomplish a suf- 

 ficient disintegration of the animal matter, such as wool, leather, silk, 

 and the like. After digestion the liquor containing in solution the 

 gluey product above referred to may be removed, either by ordinary 

 drainage and ablution, or by the action of a centrifugal hydro-extractor 

 or by subjecting the mass to powerful pressure. The partially dried 

 mass thus obtained may next be opened and loosened and have its desic- 

 cation completed in any way. When dried the material may be sub- 

 jected to any suitable mechanical process of beating, shaking, sifting, 

 and the like. The animal part will be found to possess that greater 

 degree of friability and that more easy and complete separability from 

 the intermixed vegetable fibre, which it is the special object of the pre- 

 sent invention to secure. The vegetable fibre also, freed as it thus may 

 be from gluey impregnation and thoroughly disencumbered of adherent 

 animal matter, will be found to bleach more easily and to attain a 

 brighter whiteness with less consumption of bleaching liquor, and con- 

 sequently less impairment of tenacity than when treated by former 

 modes. In some cases, however, high-pressure digesters are dispensed 

 with, and the process is conducted at ordinary atmospheric pressure and 

 at (or even in some cases below) the ordinary boiling point of water ; 

 making up, in such cases, either by length of the time of treatment, or 

 by increase of the dose of caustic earthy solvent, or in both ways, for the 

 diminished chemical activity resulting from the lowered temperature. 

 In some cases indeed, when time is no object, the process may be con- 

 ducted at the ordinary temperature of the atmosphere, the maceration 

 being continued with occasional agitation until the animal matter is 

 found to be sufficiently disintegrated, and a due proportion of the gluti- 

 nous animal matter dissolved. The temperature, however, preferred, 

 when oj)erating on average commercial mixed rags, is the ordinary 

 boiling point of water, or 212 deg. Fah. ; and in thus operating it is 

 best to add to the rags about 5 per cent, of their weight of quick- 

 lime, and three or four times their weight of water, the lime and the 

 water being mixed so as to make a milk of lime, and the boiling being 

 continued for about three hours, after which the squeezing, drying, and 

 beating processes may be applied, as above described. 



Silk, which resists much more than leather and wool disintegration 

 by hot steam, only yields readily under the combined attack of hot 



