CELLULOSE. 553 



splinters are placed in sheet tin perforated vessels that are 

 put into a fixed horizontal boiler. When the boiler is full 

 of these vessels, it is hermetically closed, pumped full of a 

 solution of soda, and boiled under pressure of 10 ats. by 

 means of a fire kindled below it. After 3 to 4 hours the boiler 

 is emptied. The raw cellulose thus obtained is washed, refined, 

 bleached, and pressed successively by several drying rollers, 

 coming out in the form of felt. From 75 to 80% of the 

 solution can be used again. This solution is known in the 

 trade as " soda-cellulose." 



More recently this soda process is being abandoned for that 

 of preparing cellulose by means of sulphuric acid, which is 

 brought into contact with the wood splinters in the form of a 

 solution of calcium sulphate. In this method, introduced into 

 Germany by Mitscherlicb, the splintered wood is placed in 

 large boilers and steamed, then the solution of calcium sulphate 

 is admitted and boiled with a pressure of 2J to 5 ats. for 50 to 

 60 hours. The solution comes from tall towers filled with 

 lime, through which sulphurous acid from burning sulphur 

 passes while water trickles in from above. The solution of 

 calcium sulphate is collected in reservoirs below. The material 

 coming from the boiler is in reddish -yellow soft pieces, that 

 are pounded, washed, passed through sieves, and pressed into 

 felt by rollers. 



Cellulose made by both the above processes is used partly 

 for paper-making, partly for wood-pulp (p. 501). There are 

 in Germany 600 cellulose factories using annually 1J millions 

 of cubic meters of wood. 



Kellner's electrical process for preparing cellulose con- 

 sists in boiling the wood with solutions, chiefly of salt, 

 and at the same time passing an electric current through it. 

 This separates the incrusting material from the cellulose. 

 It cannot be denied that there is now in Germany an over- 

 production of wood-pulp, that is increased by the competition 

 of America and Asia. 



The following articles are made of cellulose : Ornamental 

 relief -work in small pieces for artistic furniture and picture- 

 frames ; also entire pieces of furniture, the seats of chairs, 

 casks, buckets, tubs, laboratory and cooking utensils, etc. ; 



