372 OPINIONS OF SCIENTIFIC MEN. 



ammonia which it contains. Ammonia, commonly known 

 as hartshorn, is an exceedingly powerful stimulant. 

 Nor will it appear unimportant, when we bear in mind 

 that two and one-quarter pounds of this ammonia, lost 

 by fermentation, is equal, according to some, to the loss 

 of one hundred and fifty pounds of grass or grain. 



Scientific men will say that this gas is taken up in the 

 atmosphere by the rain, and descends with the rain to 

 fertilize the earth; and this is probably true. This 

 ammonia, so valuable, so indispensable to the earth, is 

 not lost forever when it flies away into the air ; but the 

 shrewd farmer will perceive that as much of it as he 

 allows to escape from his own hands, by neglect, falls 

 upon and improves the fields of his neighbor as much, 

 and perhaps more, than his own. Is it not evident that, 

 by saving all that we can, and by receiving whatever 

 the genial rain brings with it, we get a double benefit ? 



If the effect of plaster is such as has been described, 

 no one can fail to see how important are the functions 

 it may be made to perform. But it also adds a certain 

 amount of lime and sulphur to the earth. It is com- 

 posed of these substances for the most part, and hence 

 called by chemists sulphate of lime. I shall have occa- 

 sion to speak of its use in connection with other ma- 

 nures in the compost heap, and I now allude to its use 

 by itself, simply as a top-dressing. 



On some soils it is not so satisfactory as on others ; 

 but our pastures are, many of them, covered with the 

 white clover or honeysuckle, and these are often called 

 clover lands. On all such lands, whether reserved for 

 pasture or mowing, plaster generally has a wonderful 

 influence. A bushel, or two bushels, to the acre, have 

 been known to double the crop, and to add more than 

 twenty times its own weight to it, while even greater 

 results have followed. For, if we may believe Bous- 



