132 Transactions. — Miscellaneous. 



case the pile rises considerably above the surface of the cavity, but the whole 

 must be carefully covered with sods, etc., as already described. A pile 

 containing 50,000 cubic feet requires a fortnight for the process of com- 

 bustion. It need scarcely be remarked that the wood must be dry before 

 the operation is commenced. 



In the Highlands of Scotland tar is sometimes extracted by a somewhat 

 rougher method. A hole is dug in the side of a hill, a gutter being formed 

 at the bottom of the hole, and terminating in a small aperture on the 

 outside. The hole is filled with wood cut in proper lengths, and the top is 

 covered with tiles or sods. The tar gradually drains into the gutter, and is 

 discharged by the external aperture, which must, of course be very small, or 

 air will be admitted in such quantity as to burn the entire mass. 



Creosote, 



Although this paper is concerned chiefly with products requiring at most 

 a very simple process to prepare them for market, I venture to include 

 creosote, as there can be no doubt that it will be greatly in demand as a 

 preservative for timber used on our railways and other large works. The 

 high rates paid for labour render the durability of timber of far greater im- 

 portance in New Zealand than in Great Britain, where railway-sleepers are 

 almost invariably saturated in creosote, on account of its antiseptic properties. 



Creosote is distilled from wood-tar, chiefly from the tar of beechwood, 

 which yields a larger proportion than other kinds. The chief supplies are 

 obtained from the White Sea, the Baltic, and North America. It might be 

 obtained in unlimited quantity from the beech forests of the sub-alpine parts 

 of the colony. 



The so-called creosote of coal-tar is simply " more or less impure carbolic 

 acid," which does not occur in wood. 



Amongst the products obtained from the destructive distillation of wood 

 are acetic acid, wood-spirit, paraffin, anthracene, etc. 



Pitch. 



This is obtained by boiling wood-tar until nearly one-half of its bulk is 

 evaporated, when the remainder is allowed to cool and harden into pitch. 

 The process is usually effected in copper boilers set in brickwork, to diminish 

 the risk of accident. 



Lampblack. 



This is merely the fine soot given off during the manufacture of tar or 

 charcoal. It is deposited on the sods which cover the billets, and must be 

 scraped off. If, instead of the rough processes described above, closed ovens 

 were used, the lampblack would be deposited on the roof. 



A superior kind is manufactured in a more systematic manner from the 

 straw and other waste material used in the preparation of the resin of the 



