OF ARTIFICIAL MANURES. 167 



mated at 2d., and the lime carried over at an addi- 

 tional rate. 



7. Sulphate of lime (gypsum) : — 1 lb. = a far- 

 thing. At this price powdered gypsum may now be 

 obtained for agricultural purposes (in Saxony). 



8. Carbonate of lime (pulverized limestone) : — 1 lb. 

 = about half a farthing. This is about the aver- 

 age price of burnt lime in Saxony. If this latter is 

 suffered by long exposure to the air to become 

 changed into carbonate of lime, the price must then 

 be reduced to one third of a farthing, — a sum 

 which may be imposed upon those manures that are 

 very rich in lime (for instance, marl, gas-lime, etc.) . 

 In most artificial manures the lime is of subordinate 

 importance, and the difference that would be pro- 

 duced in the total price by assuming one third, in- 

 stead of half a farthing, is scarcely worth considera- 

 tion. The carbonate of magnesia, if specially men- 

 tioned in the analysis, may be reckoned at the same 

 sum with that of the carbonate of lime. 



Such are the substances and the prices I have to 

 propose in defining the value of artificial manures. 

 The additional ingredients usually exhibited in 

 chemical analyses, alumina, silica, and oxide of iron, 

 have been disregarded in the computation. I have 

 not brought forward a specific calculation for sul- 

 phuric and muriatic acid, because to appraise these 

 specially would involve in a chemico-agricultural 

 analysis, for the most part, an excessive prolixity of 

 detail, and too great a sacrifice of time. They have 



