ANALYSIS OF SOILS. 
59 
last fitting into a tin pot which will hold about a pint of water, a cover being made 
to fit on the top sieve." Sieve 1 — the uppermost — is made of a perforated tin 
plate, the holes about one-twentieth of an inch in diameter. The largest particles 
or stones are retained by this sieve, and the remainder is successively passed through 
two or three more sieves, increasing in fineness to the last, which is of the finest 
wire-cloth, having from one hundred and fifty to one hundred and seventy threads 
in an inch : whatever passes through this is an impalpable powder. 
By this simple method any soil previously dried, as before directed, is separated 
into four distinct parcels ; but to render the separation more complete, our author 
instructs us to apply his compound cylindrical sieve in the following manner : — All 
the siftings may be done in one operation, by placing the dried earth in the upper 
compartment, — -having previously pulverized any remaining lumps of the earth. 
"The coarser sand must be washed with pure water to detach any fine dust adhering 
to it ; what runs through may be used to wash No. 2 (from tlie top) in the same 
manner, and then may pass through No. 3 to the impalpable matter which passed 
through all the sieves. A sufficient quantity of water must be used to render the 
whole of this last nearly fluid. There will be three different portions of the washed 
soil left in the sieves, and a portion of impalpable matter diffused through the 
water in the lower division of the instrument." 
This fine matter is to be well shaken, and suddenly poured into a deep glass 
vessel, and permitted to settle till the heavier sand subsides ; and then the light, 
floating soil is to be cautiously poured off into another vessel. This washing may 
be repeated till all the sand of which the particles are visible to the naked eye is 
separated. But it is correctly observed that a little practice will enable a skilful 
operator to effect this at one operation. 
We must defer our notice of those parts of the essay which approach to a 
chemical analysis, and shall conclude with one more quotation. In order to detach 
the Jmmus^ " the earth and water decanted out of tliis last vessel are poured into 
a glass tube eighteen inches long the bore of which is less than an inch ; one 
end is stopped with a cork, and the other has a small lip for the convenience 
of pouring out the contents." In a short time an earth, chiefly alumina^ will be 
deposited. What remains suspended in the water is to be poured off into a similar 
tube ; and this fluid " will contain nearly the whole of the humus^ which will 
take some hours to be deposited in the form of a fine brown mud." 
( To be continued. ) 
