370 Report on a re-examination of the 
cleared up, although there remains the best reason for supposing 
that it chiefly depends upon their capacity to afford carbonic acid. 
The more alkaline the bases united with these acids in a particu- 
lar soil, the more favorable are the conditions for vegetation, a 
fact which is apparently connected with the superior solubility of 
alkalescent salts. 
It may be doubted whether the steps directed to be taken in 
the analysis for the determination of the salts of lime are free from 
all objection. The treatment of the soil after being freed from 
geine, with dilute hydrochloric acid, must necessarily take into 
solution aluminium and iron, beside rendering a portion of the 
silicic acid soluble. On evaporating the fluid to dryness as di- 
rected, and treating the mass with boiling water, it would there- 
fore follow that a residuum of alumina and sesquioxide of iron, 
(owing to the partial decomposition of the chlorides of aluminium 
and iron from evaporation to dryness,) together with some silicic 
acid (rendered insoluble by the same treatment,) would go to in- 
crease the weight assumed to be pure phosphate of lime. 
As might be anticipated therefore, we find the ratio of phos- 
phate of lime in the soils of Massachusetts exceedingly high, va- 
rying from 0.5 to 2 per cent. 
Growing out of the same procedure, it appears also, that the 
proportion of sulphate of lime must generally be rather too high : 
for if, as we suppose, the hydrochloric acid attacks the aluminium 
and iron, the aqueous solution regarded in the formula as chlor. 
calcium only, must contain also the chlorides of iron and alu- 
minium, as well as some silicic acid. Consequently, we find the 
sulphate of lime quoted in some of these analyses at 3 p. ¢., and 
even higher in a few instances. 
The foregoing inadvertencies (as they strike us) in Dr. Dana’s 
rules of analysis, are not conceived to vitiate in an important man- 
ner the results contained in the report, nor do we mention them 
because we imagine they were unperceived by the inventor of 
the formula or by Prof. H.; but through a desire to induce these 
gentlemen to obviate, if possible, the objections urged against it, 
and still preserve its claims to convenience on the ground of fa- 
cility of working and accuracy of result. 
The report contains the following remarks respecting the re- 
sults of these analytic investigations. 
