Hence we see that lime should be burned, and not slaked, before being transported, as it would be unprofitable to transport the large quantity of carbonic acid and water contained in carbonate of lime and slaked lime. The quick-lime may be slaked, and carbonated after reaching its destination, either before or after being applied to the land. [What is the best form for immediate action on the inorganic matter in the soil? For most other purposes?] As has been before stated, much is gained by slaking lime with _salt water_, thus imitating the lime and salt mixture. Indeed in many cases, it will be found profitable to use all lime in this way. Where a direct action on the inorganic matters contained in the soil is desired, it may be well to apply the lime directly in the form of quick-lime; but, where the decomposition of the vegetable and animal constituents of the soil is desired, the correction of _sourness_, or the supplying of lime to the crop, the mixture with salt would be advisable. _The amount of lime_ required _by plants_ is, as was before observed, usually small compared with the whole amount contained in the soil; still it is not unimportant. OF LIME. 25 bus. of wheat contain about 13 lbs. 25 " barley " 10-1/2 " 25 " oats " 11 " 2 tons of turnips " 12 " 2 " potatoes " 5 " 2 " red clover " 77 " 2 " rye grass " 30 "[AH] [What is the best guide concerning the quantity of lime to be applied? What is said of the sinking of lime in the soil? What is plaster of Paris composed of? Why is it called plaster of Paris?] The amount of lime required at each application, and the frequency of those applications, must depend on the chemical and mechanical condition of the soil. No exact rule can be given, but probably the custom of each district--regulated by long experience--is the best guide. _Lime sinks in the soil_; and therefore, when used alone, should always be applied as a top dressing to be carried into the soil by rains. The tendency of lime to settle is so great that, when cutting drains, it may often be observed in a whitish streak on the top of the subsoil. After heavy doses of lime have been given to the soil, and have settled so as to have apparently ceased from their action, they may be brought up and mixed with the soil by deeper plowing. _Lime should never be mixed with animal manures_, unless in compost with muck, or some other good absorbent, as it is liable to cause the escape of their ammonia. PLASTER OF PARIS. _Plaster of Paris or Gypsum_ (sulphate of lime) is composed of sulphuric acid and lime in combination. It is called 'plaster of Paris,' because it constitutes the rock underlying the city of Paris. [Is it a constituent of plants? What else does it furnish them? How does it affect manure?