128 PLANT PRODUCTS 



It is necessary to make the preservative enter well into the 

 pores of the wood. If the wood is at all wet, ordinary 

 creosote fails to penetrate, but a solution of zinc chloride 

 will work under these circumstances. Both treatments are 

 sometimes used, giving a blue-purplish colour to the wood. 

 By adding to ordinary creosote i or 2 per cent, of wood tar, 

 and an equal bulk of water, and adding enough sodium 

 hydrate to make about J per cent, of sodium hydrate in the 

 total mixture, an emulsion can be produced which will 

 penetrate well into any timber, even when other methods 

 are unsatisfactory. These mixtures of soda, water, creosote, 

 and wood tar can be applied cold, with a brush, to common 

 larch and pine, giving a pleasing brown colour to fences and 

 outhouses. Creosote can also be induced to enter into well- 

 seasoned wood by heating the creosote, or by the use of 

 pressure. Timber can be kiln dried when time presses. 



Paper. — Many of the above types of cellulose can be 

 used for the manufacture of paper. In former days, the 

 materials employed for the manufacture of paper were 

 linen, cotton rags, ilax and hemp. Now, however, wood 

 pulp, bamboo, straw, many rushes, grass, peat, beetroot 

 refuse, potato stalks, have all found an entry into the paper- 

 making industry. The potato stalks of town allotments 

 could be collected economically. I^arge quantities of wild 

 grass, such as Soudan sudd, are at present unused, owing to 

 transport difficulties. 



Mechanical pulp is produced by tearing wood to pulp. 

 Stdphite pulp is produced by treating wood with sulphur 

 dioxide and water. The solution often used is one containing 

 about 10 per cent, of sulphur dioxide, employed at a pressure 

 of about five atmospheres at lOO** Cent. Disintegration 

 takes about twelve hours, more or less, according to the 

 nature of the wood. 



The miscellaneous materials which can be put to the 

 making of paper have first of all to be disinfected, then cut 

 into small pieces, and run through special cutting machines. 

 To remove greasy matters, the materials are boiled with 

 a solution of caustic soda and caustic lime. I^inen rags will 



