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(ferrous oxide, a plant poison, into ferric oxide, a plant food); it 
promotes the process of nitrification by encouraging the presence 
of special micro-organisms; it increases the fertility of the soil 
by helping some of the chemical processes which result in the more 
ready absorption by the soil of phosphoric acid, potash, and am- 
monia. Clay soils which show a tendency to “puddle” and form 
clods when improperly tilled, are greatly improved by a dressing 
of lime. This substance possesses the property of flocculating or 
coagulating the clay particles, thus opening the pores of such soils 
and making them less retentive of water and more permeable to air. 
Quick or caustic lime, which results from the burning of lime- 
stone or carbonate of lime, is, chemically speaking, carbon oxide 
(CaO), of which it loses 44 per cent. when roasted. It acts more 
energetically than carbonate of lime, or mild lime, and should be 
preferred for peaty and sour soils. Oyster shells and marble 
give the purest lime; our coastal limestone is not so pure and con- 
tains 6 to 20 per cent. of sand. 
This quick lime when moistened takes up 24 per cent. of water 
and oxygen and becomes “slaked lime” or “hydrated oxide of lime,” 
which, when exposed to the air, absorbs carbonic acid and reverts to 
carbonate of lime (CaCo,). 
Thus— 
20ewt. pure limestone yields. 
1144ewt. quick lime, or 
1484ewt. slaked lime; 
or putting it another way: 
20ewt. quick lime when slaked produces 
26ewt. slaked lime. 
During this process it increases considerably in volume, and 
falls to powder. A bushel of good stone lime weighs, when quick, 
90lbs.: when slaked, it will measure nearly three bushels; each of 
which will weigh about 45lbs. A busliel of unslaked oyster shell 
lime weighs 60lbs. When slaked it will measure something over two 
bushels, each of which will weigh 40lbs. 
The quantity of lime to use at one application depends on the 
amount of vegetable matter the soil contains. Thirty bushels of 
lime (12ewt.) is a safe application if the soil is quite thin and econ- 
tains but little vegetable mould. Several small applications of lime 
are safer than one heavy one. The chief objection of using lime in 
the quick or the slacked form is that it floats in the air as a eaustie, 
impalpable powder, which is trying to the eyes and nose and also 
to horse and harness. Gas lime is another fairly cheap source of 
agricultural lime. It rarely, however, contains more than 40 per 
cent. of lime, the rest being made up of moisture and compounds 
of sulphur or sulphites and sulphoeyanates, which are injurious to 
vegetation, and should be allowed to be corrected by the action of 
the air before being ploughed in. During this operation the noxious 
