On the Use of Ilomc-fjroton Tivihcr. 
209 
bo indacod to favour the Society at no distant period with his 
views on tlic subject. 
In the meantime I trouble you with a few remarks in order 
that those who are in a position to profit by the decision may 
be induced to givo their early attention to the matter. 
We have loiij; been in want of a cheap and generally appli- 
cable mode of rendering timber more durable, either by ex- 
pelling the saj) and filling up the pores of the wood with substances 
(if a less changeable and destructive nature, or by so neutralising 
the efiect of the sap and altering its character as to produce the 
same result. 
Sap, it is well known, is the first and most })owcrful cause of 
decay in timber, since tlie fermentation of its albuminous com- 
pounds is the cause of the production of cryptogamic, or lungoid 
vegetation, and the deposit of tlie eggs of zylophagous insects. 
Sap, also, is the primary cause of dry rot, for it is the putrefactive 
fermentation of sap which affects in the first instance the woody 
fibre, and inducing decomposition, causes that entire destruction 
of the whole substance of the timber which too often brings 
about the worst results. 
Many methods of preventing these evils or arresting the pro- 
gress of decay have been proposed. Some of them have for their 
object the destruction or evaporation of the sap, and the conse- 
quent closing up or hardening of the woody fibre. Others are 
designed to attain the same result by the destruction of the albu- 
minous constituents of the sap, or by forming insoluble preci- 
pitates with metallic salts. To attain the first of these objects, 
viz., the destruction or evaporation of the sap, heat, obviously is 
the readiest agent, and from the earliest ages it has been a 
common practice to char the ends of timbers intended to be 
e.\posed to the action of damp or alternation of temperature. 
Several improvements upon this expedient have been proposed. 
Amongst others, I may mention the process of smoking timber 
in a drying-stove, recommended by a French authority named 
Guilbert. The processes, too, of preventing decay by the 
total expulsion of the sap, and by the neutralisation of its pro- 
perties, have had many exponents. Amongst others, 1 may espe- 
cially refer to Mr. Kyan, who may be regarded as the pioneer 
of the theory of injection, and whose method of injecting chlo- 
ride of mercury is distinguished by his name. Burnett's system 
of injecting chloride of zinc. Lege and Pironnette's system of 
injecting sulphate of copper, Mr. Payne's preparation by in- 
jecting sulphate of iron and muriate of lime, and Mr. Bethell's 
process of creosoting, are all methods of similar character, though 
employing different agents, the inventors of which follow the same 
principle as that adopted by Mr. Kyan. Mr. Clift, In describing 
Bethell's creosoting process, uses these words, which clearly repre- 
YOL. IV, — s. S. r 
