. I. AGRICULTURE AND RURAL ECONOMY. 315 



through the atmosphere, and driven forward by the winds 

 until it is carried by rains down into the soil, where it de- 

 stroys vegetation, the effect being quite similar to that of 

 the same gases as thrown out of manufacturing establish- 

 ments. As, during the war, many thousand tons of powder 

 were burned, it would be quite easy to understand that an 

 immense number of cubic feet of sulphuric acid must have 

 been thrown off into the atmosphere. 10 (7, August 1,104. 



SEASON FOE CUTTING TIMBEE. 



According to Dr. Hartig, March and April are the most 

 favorable months for cutting timber intended to be used by 

 builders and carpenters, the average per cent, of moisture be- 

 ing less than forty-seven, while in the three following months 

 the average is forty-eight, and in the three winter months 

 fifty-one. He states that properly-seasoned timber contains 

 from twenty to twenty-five per cent, of water, and never less 

 than about ten per cent. ; and if the moisture is entirely re- 

 moved by artificial means, the wood loses its elasticity and 

 flexibility, and becomes brittle. Any artificial seasoning of 

 wood should be carried on very gradually, the temperature 

 at the beginning being low, and the process not conducted 

 too far. 8 A, January r , 1871, 12. 



SEASONING OF WOOD. 



A writer in an English journal informs us that small pieces 

 of non-resinous wood can be seasoned perfectly by boiling 

 four or five hours, the process taking the sap out of the wood, 

 which shrinks nearly one tenth in the operation. The same 

 writer states that trees felled in full leaf, in June or July, and 

 allowed to lie until every leaf has fallen, will then be dry, as 

 the leaves will not drop of themselves until they have drawn 

 up and exhausted all the sap of the tree. The time required 

 is from a month to six weeks, according to the dryness or 

 wetness of the weather. The floor of a mill laid with poplar so 

 treated, and cut up and put in place in less than a month after 

 the leaves fell, has never shown the slightest shrinkage. 

 18 A, February 3, 471. 



