110 CULTURE OF FARM CROPS. 



sufficient to carry it for hundreds of yards. Any one who 

 tries the experiment of gently shaking a muslin bag contain- 

 ing coarsely powdered charcoal, in a gentle wind, will find 

 that the operation of sowing, as we may technically express 

 it, a ten acre field would certainly not cost one-tenth part 

 of the labour of sowing the same field with plaster ; and 

 as that operation is not unfrequent in this country, a prac- 

 tical guide is at once furnished of the amount of labour 

 the operation involves. Powdered charcoal thus sown is 

 very uniformly distributed by the least motion of air, and 

 its effects are marvellous. In a stable, for example, strongly 

 smelling of ammonia from fermenting urine, ari ounce of 

 powdered charcoal, shaken by means of a muslin bag or 

 any fine net work, rapidly and uniformly distributes itself, 

 and instantly absorbs the ammoniacal vapours. A curious 

 instance of the action of this deoderizer occurred at Bala- 

 clava during the heat of summer, when the stench was al- 

 most intolerable in that painfully celebrated harbour. A 

 ship-load of charcoal arrived packed in bags, and the men 

 who were engaged in transferring the cargo to the shore 

 were covered with the dust, as was every object in the 

 neighbourhood the stench which before prevailed sud- 

 denly and completely disappeared. Nothing is more simple 

 than the manufacture of charcoal. A few billets of wood 

 are to be piled like cordwood, then well covered with sods, 

 with the exception of two orifices, one to admit a little 

 lire, and the other to allow the smoke to escape, until the 

 heap has well taken, and then to be firmly closed for the 

 purpose of allowing slow combustion to go on in the ab- 

 sence of air. When cool, the charcoal may be crushed in a 

 stout canvas bag by a lever, not by blows, and when sifted, 

 furnishes the required material for sowing. If we ^assume 

 with Fresinius that the quantity of ammonia in the at- 

 mosphere amounts to less than one ten-millionth, the 

 amount it would contain would exceed 50,000,000 tons, 

 while that of the carbonic acid in the atmosphere is 

 3,300,000,000,000 tons, the weight of the air itself being 

 5,050,000,000,000,000 tons or five thousand and fifty 



