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lime ; it must be collected on the filtre, and dried 
at a heat below that of redness. 
The remaining fluid must be boiled for a quarter 
of an hour, when the magnesia, if any exist, will 
be precipitated from it, combined with carbonic 
acid, and its quantity is to be ascertained in the 
same manner as that of the carbonate of lime. 
If any minute proportion of alumina should, 
from peculiar circumstances, be dissolved by the 
acid, it will be found in the precipitate with the 
carbonate of lime, and it may be separated from 
it by boiling it for a few minutes with soap lye, 
sufficient to cover the solid matter : this substance 
dissolves alumina, without acting upon carbonate 
of lime. 
Should the finely-divided soil be sufficiently cal- 
careous to effervesce very strongly with acids, a 
very simple method may be adopted for ascertain- 
ing the quantity of carbonate of lime, and one suf- 
ficiently accurate in all common cases. 
Carbonate of lime, in all its states, contains a 
determinate proportion of carbonic acid, i. e. nearly 
43 per cent., so that when the quantity of this 
elastic fluid given out by any soil during the solu- 
tion of its calcareous matter in an acid is known, 
either in weight or measure, the quantity of car- 
bonate of lime may be easily discovered. 
When the process by diminution of weight is 
employed, tw^o parts of the acid and one part of the 
matter of the soil must be weighed in two separate 
bottles, and very slowly mixed together till the 
effervescence ceases : the difference between their 
weight before and after the experiment denotes 
