m 



THE GENESEE FAEMEK. 



acid, no matter from what source, coming in contact witli lime either in soils or rocks, 

 produces gypsum. In some localities, crystalizcd plaster is formed so rapidly in the 

 manner indicated, as to throw down, like frost, stone walls, and crack the walls of brick 

 and stone Luildings. When this phenomenon was first observed, much speculation Avas 

 had " on the growing of beds of gypsum." Plaster can groAv in soils and beds so long 

 as lime and sulphur last, but no longer. Lime and sulphur are indispensable elements 

 in all soils, and every farmer should be able to determine by the use of the appropriate 

 tests, the existence of gypsum or lime in the land he occupies, whether in meadow, 

 pasturage, or tillage. This information we shall give in the present volume, when we 

 come to describe the analysis of soils. To the million, a knowledge of chemical princi- 

 ples is more important than sny description of analytical manipulations, which not one 

 in. a thousand will ever practice. But many operations in the laboratory are so simple 

 that any farmer may perform them with success, after a little study. If students in 

 academies and advanced classes in public and private schools, were instructed in the 

 uses of filters and solvents, to separate dissolved from undissolved substances, and in the 

 application of reagents as tests in agricultural researches, an important step would be 

 taken in the right direction. Because a youth can not reach the highest eminence in a 

 science, there is neither sound sense nor decent logic in the inference, that he should 

 make no effort to learn what he can of said science. Facts are the basis of all know- 

 ledge, and the habit of ascertaining and recording fiicts in rural affairs, both in practice 

 and theory, should be encouraged from boyhood to old age. Apply the inductive system 

 of re'asoning and research to agriculture, and the tens of thousands of able men engaged 

 in it will rapidly expose and correct the errors of the past, and enlarge the bounds of 

 what is already known in tillage and husbandry. 



Specific gravity are words used in chemistry to denote the relative weight of any 

 given volume of a solid, liquid, or gaseous body. In all weights and measures, some- 

 thing is arbitrarily assumed as a standard with which other things are to be measured 

 or weighed. Pure water, when the thermometer is at 32 dog., or at the freezing point, 

 and th£ barometer at 30, furnishes a standard much used by chemists. Thus, a bottle 

 that will hold an ounce (480 grams) of distilled water, will contain only 343 grains of 

 sulphuric ether, which is much ligliter than water. It will, however, hold 885 grains of 

 oil of vitriol, or sulphuric acid. If we make water a unit, and place it at 1000, the 

 specific gravities of ether and sulphuric acid will stand thus : 



Grains. Sp. Oraviiy^. 



"Water, 4S0 inoo 



Ethpr 343 715 



Sulphuric acid, 8s5 1845 



To save the trouble of calculation, the bottle in use is generally made to hold 1000 

 gi'ains of pure water, and then filling it with the fluid to be tried, the Aveight gives 

 directly the specific gravity. By means of a light but more capacious glass globe, the 

 comparative weight of gases is ascertained. A gas must be either perfectly dry, or satu- 

 rated with moisture. Assume that the globe contains 28 cubic inches, and when filled 

 Avith dry common air of a knoAvn temperature, (32 deg.,) Aveighed 656 grains. With 

 the air removed, it might Aveigh 647.5 gi-ains, shoAving a loss of 8.5 grains. Filled with 

 dry carbonic acid at the same temperature, it would Aveigh 660.3. If Ave subtract the 

 weight of the globe (647.5 grains) from the same filled Avith carbonic acid gas, the 

 difference is 12.8', Avhile that of common air is 8.5. Call the latter 1.000, and the 

 specific gravity of carbonic acid gas is 1.506. Variations in temperature and barometric 

 pressure change the relations of gases very materially. 



How to determine the specific gi-avity of soils and other solids, will be explained in 

 our next. 





