ON PREVENTmC THE DRY-ROT IN WOOD. ^i^ 



XL 



An Tnqiiirtj into tlie Causes of the Decay of Wood, and the 

 Means of preventing it. By C. H. Parry, M. D. 



(Continued from Vol. XJX, p. 338. J 



W, 



-rot. 



HEN wQod decajj^s under cover, that condition is usu- Dry-r 

 all}' called the dry-rot. Let us examine the circuipstances 

 in which this change takes place. 



It affects the interior doors, shelves, laths which subdivide Places where it 

 the layers of wine, and all other wood work in certain eel- ^^^j.^ ^ 

 lars; beams and rg^fters which support the roofs of close 

 passages ; joists laying^ on or near the earth ; the wainscot- 

 inij of large rooms, little inhabited, in old and especially 

 single houses; and wood in various other situations of a 

 similar kind, which need not be particularized. In some of 

 these cases, while one sample or portion of wood shall suffer 

 the drj-rot, another specimen or portion shall remain un- 

 changed. In other instances, wood of various kinds and 

 qualities has been successively employed, and all has alike 

 suffered. During the stages of change, a crop of mucor or Attended with 

 mould, and very frequently of fungi, has sprung from the ^"'^"'V'*'^ ""* 

 porous mass; and the decay is ^Iwyys attended with a \yide- liar smell. 

 spreading exhalation, the odour pi' which cannot well be 

 described, but which is sufficiently known. 



What then are the causes of this destruction; Precisely Cause, 

 the same as those which I have before described; though 

 their action is differently modified, and less obvious to gross 

 observation. The decay is produced by the putref;jctiyQ 

 fermentation of the component parts of the wood, in con- 

 nection with moisture, \yithout which, as I havejaefore stated, 

 >*ood cannot putrefy. 



Common air is not only capable of mixing with a con- Air loaded 

 siderable quantity of \yater in form of vapour, biit during ^'"^ water, 

 every state of our atmosphere is always much loaded with 

 it. AVater becomes vapour in couseijuence of being united 

 with a certain proportion of that subataiic^ which is called 



heat. 



