PAPER MAKING 515 



The mixed rags or other such materials containing azotised matter 

 mixed with vegetable fibre after being well beaten (preferably in a paper 

 maker's rag-beating machine) to separate inert dust and grit, are 

 put into 'the cradle or cradles and lifted into the digester, the lid of which 

 is then screwed down steam-tight. Steam from a generator is then 

 turned on through a tube and stop-cock in the usual way, at a tempera- 

 ture and for a time which may vary within wide limits. Mr. Ward has 

 obtained good results, for example, with steam at from three to seven 

 atmospheres pressure, kept up for from two to four hours' time, the time 

 being lengthened when the temperature and pressure are diminished 

 and vice versa ; but he recommends as a good working average steam at 

 about five atmospheres pressure, continued for about three hours' time. 

 The effect of these arrangements has been found to be, on the one hand, 

 effectually to defend the materials from the contact or drip of any 

 excess of condensation water that 'may form as aforesaid, and on the 

 other hand to admit to the materials a sufficiency of steam to hydrate 

 their azotised ingredients and to produce the above-described peculiar 

 transformation thereof. 



Any condensation water that may accumulate in the digester 

 should be discharged from time to time by the stop-cock below, and 

 as soon as the digesting process is finished steam should be suffered 

 to blow off a little while through the steam cock above. The materials 

 may thus be obtained dry from the digester, or if taken out while still 

 damp they may be dried by exposure to a current of hot air in a drying 

 chamber. 



The mechanical means available for separating the manure pro 

 duct from the fibrous product are, it will be readily understood, nume- 

 rous and susceptible of many modifications. Mr. Ward has obtaiued 

 excellent results by passing the dry product of digestion between fluted 

 wooden cylinders, such as are used in scutching flax, and afterwards 

 through an ordinary paper-makers' rag-beating machine. Care must 

 of course be taken to enclose dust-tight the space which receives the 

 valuable azotised powder beaten out, so that none of it may be blown 

 away and lost, and the machinery should be worked by steam or other 

 power at sufficient speed and force thoroughly to separate the azotised 

 dust from the fibrous vegetable matter without injuring the staple of 

 the latter or wastefully wearing it away. 



In dealing with greasy refuse, such as the oily waste of the wool 

 manufacture called shoddy, the patentee proceeds in the same manner, 

 merely omitting the final cylindering, beating and shifting process, as 

 being in this case unnecessary, and instead thereof, subjecting the ma- 

 terial to a preliminary process of pressure to exfract the oil, such pres- 

 sure being (preferably) applied by means of a hydraulic press, aided in 

 some cases by moisture and heat to facilitate the running out of the oil. 

 The cake left in the press is digested with the appliances and precau- 

 tions above set forth, and makes a superior manure, more portable, and 



