PROGRESS IN AGRICULTURE. 15 



its') ; another attributes it to ammonia ; another to electricity. 

 This same nitric acid combined with common salt, forming 

 nitrate of soda, is proven, in the experiments I have mentioned, 

 to have a special effect on grass. Why ? And this nitrate of 

 soda is found in large bodies in Utah, and in South America, 

 and on the Continent of Europe. Why does gypsum or plaster 

 (sulphate of lime) produce such marked effects on clover on 

 some soils, and very little effect on others ? How does it oper- 

 ate ? No two out of five chemists will probably agree on that. 

 Why is it that lime will cure the acidity of soils, and kill sorrel, 

 moss and dock ? Wby is it that an ox can thrive on straw, and 

 his owner only on the grain ? An Englishman and a Scotchman 

 met, and the Englishman remarked that the food (oatmeal) 

 the people ate in Scotland was only consumed by horses in 

 England. " That is the very reason," replied the Scotchman, 

 " why they have such fine horses in England and such superior 

 men in Scotland ! " Why should oats develop muscle, and corn 

 produce fat? Why is it that some plants cannot live as the 

 successors of certain others in the same spot ? Have plants the 

 power of excretion ? By what sort of function is'it that plants 

 can emit volatile substances and very sensibly affect our olfac- 

 tory nerves ? Have plants the power, like animals, of selecting 

 and rejecting food placed within their reach in the soil ? When 

 the sun shines, chemists say, plants absorb carbonic acid from 

 the air, give off oxygen and grow green ; and that during the 

 night, or in a dark place, they absorb oxygen, emit carbonic 

 acid, and grow white. Why ? And there is ammonia, one of 

 the most wonderful agents employed in the laboratory of the 

 farm. You see ammonia salts mixed with mineral manures 

 more than doubled the crops at Rothamsted. Perhaps some 

 lady present has a bottle of it in her pocket, applying it to her 

 olfactories occasionally, under the name of hartshorn. This 

 powerful agent, it is said, is composed of hydrogen and nitrogen, 

 and arises from the millions of decaying dead animals. It comes 

 down in every fall of rain, snow and hail. It is abundant about 

 horse stables, barn-yards and slaughter-houses. It, like the 

 busy bee, is at work at every plant, aiding it in assimilation, 

 painting its flowers with red and blue, and building up its or- 

 ganic elements. It is the principal constituent of guano. It is 

 so volatile that it is scarcely appreciable by the most delicate 



