44 THE FARMER AT HOM2. 



fresh water : the gullet of this cruet is shut by the extremity of the 

 leaf itself, so as to prevent the water from evaporating. 



BOG. A swampy piece of ground, usually containing large quan- 

 tities of vegetable matter, frequently of the nature of a quagmire, and 

 with tufts of coarse grass mingled with aquatic plants spread over its 

 surface, is in Europe, and also in this country, termed a bog. Such 

 pieces of amphibious soil are not cornrmn in the United States, but 

 in Scotland and Ireland, a very considerable portion of the surface is 

 occupied by such non-productive lands. Where bogs exist, the only 

 modes of bringing them under culture, are, by draining or covering the 

 surface with firm earth, and frequently it is necessary to combine both 

 operations. Draining the land consolidates the surface, and affords 

 opportunity to cut off the bogs or coarse tufts of grass, and introduce 

 more valuable grasses, if not to submit it to the action of the plough. 

 Where the boggy ground is mostly composed of vegetable matter, it is 

 desirable to incorporate the common earths with the surface, thus 

 giving increased powers of production and greater firmness. Gravel 

 or sand may be carried on when the ground is frozen, if the surface 

 is not hard enough at other times, and by thus uniting draining and 

 the application of earths to impart consistency, such soils, worthless 

 in their natural state, are rendered most valuab]e and productive. 



BOILING, or EBULITION. The bubbling up of any fluid. 

 The term is most commonly applied to that bubbling which happens 

 by the application of fire, though that which ensues on the mixture of 

 an acid and alkali is sometimes also distinguished by the same name. 

 Boiling, in general, is occasioned by the discharge of an elastic fluid 

 through that which is said to boil ; and the appearance is the same, 

 whether it is common air, fixed air, or steam that makes its way 

 through the fluid. The boiling of water is proved by Dr. Hamilton, 

 of Dublin, in his Essay on the Ascent of Vapor, to be occasioned by 

 the lowermost particles of the water being heated and rarefied into 

 vapor by reason of the vicinity of the bottom of the containing vessel ; 

 in consequence of which, being greatly inferior in specific gravity to 

 the surrounding fluid, they ascend with great velocity, and lacerating 

 and pushing up the body of water in their ascent, give it the tumul- 

 tuous motion called boiling. 



The degree of heat at which different fluids boil, is very different. 

 Spirits boil at the lowest temperature, pure water next ; at a still 

 higher temperature, the freed oils. The degree of heat at which a 

 fluid boils, is called its boilmg point. This is used as one of the fixed 

 points in the graduation of thermometers. Ether may be made to 

 boil at the common temperature, by merely exhausting the air from 

 the vessel in which it is contained. 



BOLTON GREY HENS. One of the varieties of the Hamburg 

 fowls is known by this name. The breed is much esteemed. It is 

 handsome, active, ar*i valuable for eggs as well as the richness of its 



