100 CIRCUMSTANCES TO BE STATED 



lb. 



Slaked lime, (hydrate of lime,) .... 47 



Carbonate of lime, ...... 63 



Caustic or calcined magnesia, .... 26 



Carbonate of magnesia, . . . . . . . 54 



Sulphate of baryta, . . . . . .146 



Silicate of potash, 



Silicate of soda,* ..... ? 



Phosphate of potash, (with two of alcali, 2 KO, P 2 5 ,) 207 

 Phosphate of soda, (of the shops,) . . . . 437 



Phosphate of lime, (apatite,) t . . . .196 



Phosphate of ammonia, (with two of ammonia,) . 144 



Ammonia phosphate of soda, ..... 692 



Ammonia phosphate of magnesia, .... 238 



Carbonate of ammonia, ...... 49 



Sulphate of ammoniac, ...... 94 



Sal ammoniac, 67 



Nitrate of ammonia, . . . . .100 



From the above numbers, it will be easy to calculate how 

 much of any one substance must be used in a comparative 

 experiment against 100 lb. of any other. 



9. Circumstances which ought to be stated in regard to all soils 

 and localities selected for experiment, on publishing the 

 results of trials made upon them. 



In regard to all soils and localities on which precise and 

 rigorously conducted experiments are made, it will be necessary, 

 to a full appreciation of the results they yield, that, along with 

 the results, there should be published an account, as far as it is 

 attainable, of 



1. The proportions of silicious or other sand, fine or coarse, 

 that is, in common language, the degree of lightness of the soil. 



2. The proportion of lime in the state of carbonate, or other- 

 wise. This indicates very nearly the comparative decomposing 

 energy of soils otherwise similar. 



3. The proportion of organic, and especially of peaty matter. 



4. The effect of drought upon it whether it hardens or 



* The composition of these silicates, as manufactured, is liable to so much 

 variation, that no constant numbers can be assigned to them. See 7, chap. ix. 



f Burned bones contain 15 to 20 per cent of other matters mixed with 

 phosphate of lime. 



