668 
Analyses of Ashes of Plants. 
Carbonic acid is an ingredient of many ashes ; but in the grain 
of wheat it is seldom met Avith. The presence of carbonic acid in 
an ash indicates the existence of organic acids combined with Hme, 
&c. in the plant ; the grain of wheat, however, would appear in 
its matured state never to possess any such organic salts, and con- 
sequently the column appropriated for this acid in the table is 
almost void. 
Lime is another ingredient in the ash of wheat : in quantity it 
varies between 1-5 and 8*00 per cent., being more frequently 
near the former than the latter number. The mean quantity is 
3-61. The largest amount removed from an acre is seen in Spec. 
42, where it is 3 lbs. 9 oz. 
Magnesia is a highly important constituent of plant ashes : in 
wheat it varies between 9*00 and 14-00 per cent, of the ash — 
more often however being found to constitute 11 or 12 per cent, of 
the mineral matter. Our analyses give us as a mean 12 • 36 per cent. 
A bushel of 61 lbs. contains 2 oz., and. an acre of 28 bushels 
will remove 3 lbs. 8 oz. The largest quantity of magnesia re- 
moved in any crop examined by us was 6 lbs. 13 oz. (Spec. 47). 
Peroxide of iron exists to a small extent in the ash of wheat : 
its quantity varies between 0"25 and 3 '5, the smaller number 
being nearer the ordinary quantity. It is remarkable that those 
specimens which contaui most iron are from the chalk districts, or 
analogous soils. The average proportion of peroxide of iron is 
0-81, and the largest amount removed from an acre (Spec. 29) 
1 lb. 6 oz. 
Potash is, next to phosphoric acid, the most considerable and 
important of all the substances w hich exist in wheat ash : in 
quantity it varies between 27 and 37 per cent., having about the 
same latitude as phosphoric acid. The mean of 26 specimens is 
31 '37. A bushel of wheat (61 lbs.) will contain 5 oz , and an 
acre of 28 bushels will carry ott" 8 lbs. J 5 oz. The largest quantity 
described in the Report as removed from an acre is 14 lbs. 
Soda is an alkali scarcely ever entirely absent from wheat, but 
present only in small quantity. When compared with potash, it 
varies between 1 and 5 per cent, of the ash. In one instance, that 
of the Marianople w heat before mentioned, its quantity its compara- 
tively large, reaching 9 per cent.; but we have as yet met with 
nothing to induce us to adopt the opinion of Liebig, of the sub- 
stitution of one alkali for another. At all events this does not 
appear a usual occurrence. We have not certainly examined any 
specimens grown in soils where the total absence of the other alkali 
would necessitate a plant to assimilate soda ; but were this possible 
without great injury to the health of the plant, or defect in quality 
and quantity of the produce, why do we not find it more frequently 
the case ? If it be iudilierent to tlie plant whether the alkali fur- 
