//AM 7' OF COMHUXTKW

III

The* difference between the to.mperature at maximum and the,
tompenitiw at firing gives directly the total ruse in temperature
in tin* ejilorimder. To this ri.se a cooling correction must he
applied, which is computed as follown:
The^4 change in temperature (luring the* preliminary /> minutes
of reading divided hy the time (5 minutes) gives the rate of
change «*f temperature per minute, due to radiation to or from
tin* calorimeter, and also any heating duo. to nl-irring. Thin
factor is #j and in like manner the readings taken aft-or th(t
temp<^init utv cfian^f ha.s Ijf»(!C)ini^k uniform give Itn, ^rFhe two
rates of change of tc'inp^nitun* give tin^1. (^kxistln^ c.onditionH in
th(* calorimHer at the wtart and at tin* finish of the run. The?
al^<*hraic signs of /i*i and R» will lu* C4-) for falling t-enifxTatunss
and ( -• ) for rising feinpomfuroN. ^prh(»r(»f()n»_t t.h<i algehraic huiii
of the two rates, divided hy 2, will fcive the* ino.au rate; of chang<^ of
temperature chip to nuliation or absorption, during tho c*ntin^
ex{M»nnieiit. This valtn% nmltJplied by the time, iu nunuton
elapsing I »et\vi'cn firing «nnd the attaimnc»nt of innxitnum
ture, givi*s tin* total nulinlioa correction. Thin radiation.
tioii i.sthus

•fit

when* r •••• ntcliaiioii
/ -• tint!" from firing to maximum
and /i*s »ind It* have the* nigtiificanw already explained.
radiation correct ion nniy hav<» eithfT a positive^ or a
nigii, acconling to win*! jut the net effort wan actual radiatitm
or uimorption of heat from flu* Htirnotimling ntnioHph(»n^.
Tin* quantity ^* in af iplied to the total observed tiho, to obt.ain.
tlu* correct<*rl riw and the lnf.f,*»j% divided hy the weight of nmtcrial
b«rne«l, will give the fine pergnmi of «atnplf% Thin rine |M»rgram
in tfitzltiplied by t hi* weight, of \vitli*r used plus tho " \vai-(*r ecjuivu-
lent" of the niloriiueter and the product is calories per gram of
sample. This figure multiplied hy LH giv(*n IJ.t.u. jht pound
of Huiuple, if this iiii»fhod cjf (»x|)n^Hsion is desire*!.
Sunwiarijcinfr, if T •• lotul ohnerved feiripcTattirf? rinc! and cr
— water i't|iiivnk»nt,

- eal pc*r grn

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