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more fertile and taking a considerable effect, mixed with duiig." 

 The result of another set of experiments is very remarkable and 

 highly in favor of salt when dissolved in water and added to the 

 "dung; though poultry dung alone has been unable to stand the 

 late burning weather, yet the addition of salt to it has made it 

 prove a fine manure to the present moment. This suggests a 

 most important lesson for the addition of salt to dung-hills." Spir- 

 its of hartshorn and sal-ammonia, were tried in his experiments, 

 and he says, " the volatile alkali continues in this as in every trial 

 to triumph ! The votatile alkali has never failed of being of great 

 service. In every repetition we can make upon the volatile alkali, 

 its superiority to all other additions, is inore and more confirmed. 

 Up to that time, however, ammonia had heen declared an enemy of 

 vegetation /" Young proved that covering soil from the sun bene- 

 fits it, (Gurneyism,) " this seems to denote that covering is good 

 to destroy weeds." 



Do not our modern German chemists talk of the " destructive 

 influence of the plow" in exposing humus and ammonia to the 

 rapid evaporation of the sun's heat. And do not the teachings of 

 our men of " science with practice" point to the value of over- 

 shadowing leaves in the hot summer, to protect the gaseous riches 

 which have been stored in the soil, in the rainy months of winter 

 and spring? 



Arthur Young also lighted upon much the same truth which 

 Mr. Lawes has arrived at, relative to the power of nitrogenous 

 manure to give plants assistance to avail themselves of the " min- 

 eral manure." 



He fed plants with Priestly's phlogiston, that is hydrogen gas 

 from iron filings and oil of vitriol, causing daily a stream of the 

 gas to be thrown up through the soil in the pot from the bottom. 



In 1786, he said, " I scarcely know the the man of science who 

 has treated the subject that has not been sensible of the connection 

 between chemical inquiries and the principles of agriculture. To 

 imagine that we are ever to see agriculture rest on a scientific 

 basis, regulated by just and accurately drawn principles, without 

 the chemical qualities of soils and manures being well understood 

 is a childish and ignorant supposition. If you do not know what 



