1*44 



Every farmer knpws how quickly the sap-wood rots. Sap-wood is gradually 

 changed to heart-woo(^ by the force of pressure and of growth. The outer 

 layers seem to press upon the interior ones, causing them to contract by lessen- 

 ing the size of the pores. These pores, too, are gradually closed by cell-growth. 

 The wood is more solid, and less of air can penetrate, them. The sap almost 

 ceases to circulate in them. But in the sap-wood this circulation is undimin- 

 ished. In the spring Avhen the sap, then almost nothing but water, ascends, it 

 is fluid ; but having been acted upon in the leaf, which absorbs carbonic acid, 

 and exhales the water of the sap, it descends thicker, and is retained in the 

 cells or pores, forming cell or wood growth. 



By stripping the bark in the spring the sap, in its ascent, is exhaled or flows 

 from the pores, and no elaborated or descending sap is formed. Now, this de- 

 posit of the descending sap appears to have a great affinity for oxygen, which 

 exists in the air, and is that part of it which destroys all things that are of veg- 

 etable or animal growth after death. Timber that is stripped of its bark having 

 but little of this downward sap, the wood seasons to complete hardness, and is 

 not destroyed by the oxygen, because it is not taken up by an absorbent, such 

 as the descending sap appears to be. 



It is well known that wood always under water never rots, because the air is 

 excluded from it ; and posts rot most rapidly at the surface of the ground, 

 where the air penetrates into the pores, and aided by moisture which hastens de- 

 composition. To fill up the pores of the wood with a substance antagonistical'to 

 the oxygen of the atmosphere, and which will not dissolve in water readily, 

 must be preservative. A substance having these properties, and which will 

 solidify or harden the wood itself, is best of all others. Pyroligneous acid — an 

 acid procured by the distillation of wood — gas tar, and other substances are 

 used, but we know of no series of experiments having been made to determine 

 their relative value, and of the manner and times of their application. 



Individual experiments have often been made, but the years that must elapse 

 before they can be tested so often removes those who have made them from the 

 place where they are made, that nothing is heard of the result. But we hope, 

 through our regular correspondents, to glean some reliable information respect- 

 ing them, and we desire they will make inquiries about them, as we purpose 

 hereafter to make some interrogatories in our circulars on this subject. And 

 should any person have made such experiments, we hope he will advise the 

 Commissioner of Agriculture of the result, and thus aid in lessening one of the 

 heaviest expenses to which the farmer is subject. 



CANADIAN RECIPROCITY TREATY. 



Canadian delegates were present in this city to negotiate another treaty of 

 reciprocity. So far as we have seen, the basis of their proposition was to allow 

 the importation of some manufactures free of duty from the United States into 

 the Canadas. The Committee of Ways and Means would not concur in their 



