14 



NEAV ENGLAND FARMER. 



Jan. 



CATECHISM 



— OF — 



AGRICULTURAL CHEMISTRY AND GEOLOGJ. 



BY JAMES F. W. JOHNSTON, M. A. 



Q. Wliat is agriculture ? 



A. Agriculture is the art of cultivating the soil. 



Q. What is the object of the farmer in cultivat- 

 ing the sou ? 



A. The object of the farmer in cultivating the 

 soil is, to raise the largest crops at the smallest 

 cost, and with the least injury to the land. 



Q. What ought the farmer especially to know, 

 in order that he may attain this object ? 



A. The farmer ought especially to know the 

 nature of the crops he raises, of the land on which 

 they grow, and of the manures which he applies 

 to the land. 



I. — Of the Nature of the Crops he raises. 



Q. Of what parts do all vegetable substances 

 consist ? 



A. All vegetable substances consist of two 

 parts, one which burns away in the fire, called the 

 organic part, and one which does not burn away, 

 called the inorganic part. 



Q. Which of these two parts is the greater in 

 quantity ? * 



A. In all vegetable substances, the organic part 

 is very much the greater. It forms from 90 to 99 

 out of every 101) lbs. of their weight. 



Q. Of what elementary bodies does the organic 

 part of plaids consist ? 



A. The organic part of plants consists of four 

 elementary bodies, known by' the names of carbon, 

 hydrogen, oxygen and nitrogen. 



Q,. What is carbon 2 



A. Carbon is a solid substance, usually of 

 black color, which has no taste or smell, and 

 burns more or less readily in the fire. Wood- 

 charcoal, lamp-black, coke, black-lead, and the 

 diamond, are varieties of carbon. 



Q. What is hydrogen ? . 



A. Hydrogen is a kind of air or gas which 

 burns in the air as coal gas does, but in which a 

 candle will not burn, nor an animal live, and which, 

 after being mixed with common air, explodes 

 when it is brought near the flame of a candle. It 

 is also the lightest of all known substances. 



Q_. Wliat is oxygen 2 



A. Oxygen is also a kind of air in which a can- 

 dle burns with great brilliancy, in which animals 

 also can live, and which is heavier than hydrogen 

 or common air. It forms one-fifth of the bulk of 

 the air we breathe. 



Q. Wliat is uilrogcn ? 



A. Nitrogen is also a kind of air differing from 

 both the other two. Like hydrogen, a taper will 

 i not burn nor will an animal live in it, but unlike 

 Imlrogrn, ii will itself not burn, and therefore 

 j does not take fire when brought near the flame of 

 a candle. It is a little lighter than atmospheric 

 air, of which it forms four-fifths of the bulk. 



Q. Do all vegetable substances contain these 

 four ck'i/ieulary bodies f 



A. No, the greater number contain only three, 

 viz : carbon, hydrogen, and oxygen. 



Q. Name some of the more common substances 

 which contain only these three '. 2 



A. Starch, gum, sugar, the fibre of wood, oils, 

 and fats, contain only these three elements* 



Q, Of what substances does the inorganic part 

 of the plant consist ? 



A. The inorganic part of plants contains from 

 eight to ten different substances, namely: potash, 

 soda, lime, magnesia, oxide of maganese, silica, 

 chlorine, sulphuric acid, or oil of vitriol, and phos- 

 phoric acid. 



Q. What is potash? 



A. The common potash of the shops is a white 

 powder, which has a peculiar tastejcalled an alka- 

 line taste, and which becomes moist, and at last 

 runs to a liquid when exposed for a length of time 

 to the air. It is obtained by washing wood ashes 

 (the ashes left by wood when it is burned,) with 

 water, and afterwards boiling the liquid to dryness. 



Q. What is sodd % 



A. The common soda of the shops is a glassy 

 or crystallized substance, which has also an alka- 

 nine taste, but which, unlike potash, becomes dry 

 and powdery by being exposed to the air. It is 

 manufactured from sea salt. 



Q. What is lime ? 



A. Lime or quirfc-Mme is a white, earthy sub- 

 stance which is obtained by burning common 

 limestone in the lime-kiln. It has a slightly burn- 

 ing taste, and becomes hot and slakes when water 

 is poured upon it. 



Q. Wf/<rl is magnesia ? 



A. Magnesia is the white powder sold in the 

 shops under the name of calcined magnesia. It 

 has scarcely any taste, and is extracted from sea 

 water and fVom some kinds of limestone rock call- 

 ed Magnesian limestones. 



Q. What is iron % 



A. Iron is a hard bluish gray metal, which is 

 manufactured in large quantities in our iron-works, 

 and is used for a great variety of useful purposes. 



Q. WJud is oxide of iron ? 



A. When polished iron is exposed to the air it 

 gradually becomes covered with rust. This rust 

 consists of the metal iron, and of the gas oxygen 

 which the iron has attracted from the air, and hence 

 it is called oxide of iron. 



Q. Wh'il is oxide of manganese'? 



A. Oxide of manganese is a substance very much 

 like oxide of iron, which occurs in soils and plants, 

 usually in very small quantity. 



Q. " What ^ silica ? 



A. Silica is the name given by chemists to the 

 substance of flint, of rock-crystal, and of sand- 

 stones. 



Q. What is chlorine ? 



A. Chlorine is a kind of air which has a green- 

 ish-yellow colli r, and a strong suffocating smell. 

 A taper burns in it with a dull smoky flame. It 

 exists in common salt in large quantity. 



Q. What is sulpkkfic acid or oil of vitriol ? 



A. Sulphuric acid or oil of vitriol is a very sour 

 burning, oily liquid, which is manufactured from 

 burning sulphur, (brimstone ) It exists in com- 

 mon gypsum, in alum, and in Glauber and Epsom 

 salts. 



Q. What is jihosyhnric. acid? 



A. Phosphoric acid is also a very sour sub- 

 stance, which is formed by burning phosphorus in 

 the air. It exists in large quantity in the bones of 

 animals. 



Q. Arc all these substances to be found in the 

 inorganic part of plants ? 



A. Yes, they are to be found in the ash of all 

 our usually cultivated plants. 



