On the Analysis of Soils. 
617 
Ii(|Uor with water of pure .nmnionia, phosphate of hme (if present) 
will fall, and may be drained on a tilter and dried. Taken otf the dried 
filter, and digested with a little dilute sulphuric acid, sulphate of lime will 
result, characterized by its entire insolubility in dilute alcohol. Hence 
the sulphate washed with vinous spirits, dried and calcined, will re- 
present by its weight one-fifth more than the original weight of the 
phosphate. By the action of the sulphuric acid, the iron precipitated 
by the ammonia with the phosphate is got rid of. 
The magnesia, unless its proportion had been very great, will all remain 
dissolved as ammonia-muriate, and its quantity may be ascertained by 
precipitating it either with soda, or phosphate of soda. In the former 
case, the substance obtained when washed on a filter, dried and ignited, 
is pure magnesia ; in the latter, it is the ammonia-jihosphate of mag- 
nesia, and when dried at the moderate heat of 120° Fahr., it represents 
by its weight about six times that of the magnesia present; or for 100 
parts, 164- of magnesia. 
AVlien a complete analysis of a soil is to be made, the following ap- 
paratus is convenient : — 
A large glass flask, or matrass, with a sucked-in or concave thin bottom. 
This should hold at least a quart of water; and when the soil and dilute 
acid are introduced, it is to be placed on a stand over the gentle flame 
of a spirit lamp, while the beak of a large glass tunnel, having its mouth 
covered with a porcelain basin, filled with cold water, is inserted into 
the neck of a flask. By this arrangement a continual ebullition may be 
maintained in the mixture of soil and acid, without loss of acid, or 
nuisance from its fumes, because the vapours are condensed whenever 
they reach the cold basin above the funnel, and a perpetual cohobation 
takes place. A boiling heat may be kept up in this way till everv con- 
stituent of the soil, except the silica, becomes dissolved. Muriatic acid 
is generally preferred for the analysis of soils, and in somewhat greater 
quantity than the bases in the given weight of soil can neutralize. The 
ftinnel and porcelain basin should be properly supported upon the rings 
of the chemical stand. I generally subject 100 grains of soil to the 
action of boiling dilute acid in this way for 6 or 8 hours ; at the end of 
that period I throw the contents of the matrass upon a filter, and super- 
saturate the filtered liquid with ammonia. The silica which remains on 
the filter having been washed in the process, is dried, ignited, and 
weighed. 
The alumina, iron-oxide, and phosphate of lime, thrown down by the 
ammonia, being washed in the filter, and dried to a cheesy consistence, 
are removed with a bone or tortoise-shell blade into a silver basin, and 
digested with heat in a solution of pure potash, whereby the alumina is 
dissolved, when its alkaline solution is to be passed through a filter, 
then saturated with muriatic acid, and next super-saturated with ammonia. 
Pure white alumina falls, Avhich is to be separated on a filter, washed, 
dried, ignited, and weighed. 
The iron and jihosphate of lime on the alkaline filter mav be dried, 
gently ignited, and weighed, or otherwise directly separated from each 
other without that step, by the action of dilute alcohol, acidulated with 
sulphuric acid, at a gentle heat. Thus the iron oxide will be dissolved, 
and its solution mav be passed through a filter, while the sulphate of 
