ADDRESS BY THE PRESIDENT, NOVEMBER 3, 1875. 17 



creasote acts by coagulating the albumen, and preventing putrefac- 

 tive decomposition. Along with the creasote there are other pro- 

 ducts of the distillation of coal-tar, especially bituminous oils, 

 which enter into the cells, and, by surrounding the woody fibres, 

 prevent the action of water and air. There 'are two methods pur- 

 sued: 1. By placing the wood in a strong iron cylinder, exhaust- 

 ing the air from it by an air-pump, until a vacuum is produced 

 equal to about 1 2 lbs. on the square inch ; then the creasote is 

 allowed to flow into the cylinder, and afterwards pressure is put 

 on the creasote, by a force-pump, equal to about 150 lbs. on a 

 square inch. The timber is then taken out fit for use. 2. By 

 placing the timber in a drying-house, and passing the products of 

 the combustion of coal-tar through it. Thus the timber is dried 

 rapidly, and impregnated, to a certain extent, with oily matter, 

 and with the creasote given off from the fuel used to heat the 

 house. The timber is then taken out, and immersed in hot 

 creasote in an open tank. A load of fir timber will absorb 40 

 gallons ; close-grained woods less. A cubic foot of beech usually 

 weighs 8 lbs. heavier after being so prepared. Creasote is said 

 to prevent the decay of wood, and to stop the attacks of Teredo 

 navalis. 



Many of our plantations have suffered severely from the devas- 

 tation of insects of various kinds. Some of them feed on the 

 plants ; others form habitations for themselves in the buds, leaves, 

 and flowers. 



The species of spruce (Abies) are liable to a peculiar disease 

 produced by the attacks of an insect called Adelges abietis. This 

 disease is recognised by an alteration in the colour and form of the 

 leaves, which are aggregated together in the shape of cone-like 

 excrescences. Mr Hardy, in describing the insect and its mode 

 of attack, says : — " The original matriarch lives outside the gall, 

 remaining all winter in a dwarf state at the root of a bud. As 

 soon as the bud swells, she revives likewise, and speedily becom- 

 ing enlarged with the juice imbibed, she lays some hundreds of 

 eggs. The bud, meanwhile, instead of growing in length, becomes 

 fleshy, and this fleshiness is communicated to the leaves. The 

 consequence is an arrested bud, into the recesses of which the 

 young, issuing from the cluster of ova on the outside of it beneath, 

 betake themselves, and become soon closed in by the increased 

 irritation occasioned by their presence in its interior." 



The remedies proposed for the attacks of insects are numerous. 



VOL. VIII., PART I. B 



