L. MECHANICS AND ENGINEERING. 467 



has been preserved in this way, in moist earth, for fifteen 

 years ; and it is a fact, often noticed, that in old buildings 

 the wood filled with nails has remained sound, while the rest 

 has completely gone to decay. 14 (7, CCXIIL, 1874, 529. 



USE OF CARBONIC ACID GAS IX DRYING AND SEASONING 



TIMBER. 



According to a recent patent, moist carbonic acid gas may 

 be used advantageously in drying and seasoning timber. 

 For this purpose the timber to be dried is placed in a prop- 

 erly constructed chamber, and a fire lighted underneath, or 

 hot gases conveyed through the chamber, so as to produce 

 the necessary temperature. With the timber in the cham- 

 ber is placed a certain amount of water, and the products of 

 combustion, containing of course a large amount of carbonic 

 acid gas, are introduced into the same space. The carbonic 

 acid gas is rendered moist by means of the water, and being 

 heated to a considerable degree, acts directly upon the sap 

 of the green wood, and, in dissolving it, causes it to give out 

 some of its hydrogen, which, combining with the oxygen of 

 the acid, forms water, and then is evaporated, leaving some 

 of the carbon of the carbonic acid in the wood. The removal 

 of some of the hydrogen renders the wood less productive of 

 flame, while the action of the carbonic acid tends to prevent 

 decay in the wood, or to arrest it in the early stage. For 

 this operation the greener the wood the better. It is main- 

 tained by the inventor that, if the process is properly con- 

 ducted, and the wood not too rapidly heated, no piece of 

 wood needs to be split or damaged in drying ; that cracks 

 which may have already appeared will not be increased ; and 

 that in every respect the quality of the wood is greatly im- 

 proved, becoming much harder and denser. The cost of fuel 

 in England, for a load of fifty-two cubic feet of scantling, is 

 estimated not to exceed two shillings, and planks three inch- 

 es thick, of almost any hard wood, dry in six to eight weeks. 

 18 A, January 8, 1875, 416. 



THE STRENGTH OF WOOD AND THE EFFICIENCY OF THE AXE. 



In a recent volume of the annals of the Forest Academy, 

 at Mariabriinn, near Vienna, Professor W. F. Exner gives a 

 novel and highly instructive analysis of the elasticity and 



