end in view. ^lost of the methods deserihed arc typical and
illustrate' the different kinds of work that will he oi importance
in the future* activities of the* agricultural chemist, hi Par! Ill
Uiese and many oilier methods will he applied (o theanaly.Mr of
materials that are of great importance to agriculture* and, directU
or indirectly, to the economic life of all of our people.

Certain conventional modes of expression are common and
will he used in the* following pages. Most of t hc,*e arc familiar In
the student hut I lie following should he especially noted:

(a) Water always means distilled water, unle: - otherwise
stated.

(It) Accurately wciyhctl Nantpfea are ahvay* under- food, even
\\hen **ahouf 2 gm/' or a similar expression, j>i IIM**!, unle* •>
the* use of an approximate weight iV sp* cifuvilly <iircct« d.

(r) Temperatures are always

CHLOKIDKS

Gravimetric, by Weighing Silver Chloride. Silver
is a suh.stam'e of \(»ry slight soluhility in water and its pr«*cjpifji
tion and w(»ighing therefore form* flic ha^ for the defermiiiafinn
of chlorine* (of inorganic chlorides) and of .silver. Silver chloude
dissolves in pure wafer to the extent of ahntif 0.001.1 f/?u per
lifer. fl hi.s < orn'spowta to 0.0011 grit of hilvei or 0,0001 ^jn
of chlorine, \h the total amount of water thut i/ u -ed in the
pn»cipifatioii and W4ishing prnn»^t^ need not exceed HO er iirni
can he* made less than thi>, if nm\ he M«en that the recoveu **?'
chlorini or of «ilver may he regarded a«» prnctieidh eutupjHe,
for all ordinary purpohe.v,
However, if mu.vf he reinciiihered that silvei r'lilonde ili -jnUi*.
(\*wily in ammonium hvrlroxide and to »in ;tf*pr«'cu»hle *nt»'iif in
concentrated solutions of xoditun or polii -itiin chlori«Ii , ;»u*| «it
hydrochloric* add. It in decompiled hy wanning mil it miitiiu ot
jK>tUHsium hydroticie, silver otnle heirtg toimid,
In the det«*rminafioit of chlorine in impure rhlnriiiiM if j
n^ccvwiry to guard against the precipitation til nth««r -itvej
saltH, Mich ah pho^pliiite or ntrbomtte, hy h;ivinjf a -tiuil! exce-,
of add priHiif, Xifric acid j> M»tahl<* for ffii^ jwrpo-r »h*i