502 
MR. E. H. GRIFFITHS ON THE VALUE OF 
a = a[l — Tc {9 /3)} 
and, hence, equation (I) becomes 
in 
^il + l0)~=a{l-k{9 + ^)]-p9 .( 9 ).* 
By neglecting squares and products of small quantities (9) can be written in the 
same form as (l), thus, 
= -k^)- {p-{- a{k + l)]9, 
CIO 
and the values of X and p, become 
l + a(h + l) a(l—k/3) ^ ^ 
^ = -M-’ -M... • 
where a =■ 
Let Xj]^, denote the values of X and /x when a weight of water W] and an 
E.M.F. of fly Clark cells are used, the first suffix referring to the weight, the second 
to the number of Clark cells ; further, as before, let be the water equivalent. 
Then 
_ {1 — ^ 
~ JR (Wi + vg.^ ’ 
(ySj is written for ^ as its value is dependent on n). 
Similarly 
JR(W3 + W,). ^ 
Hence, by division of (11) and (12), 
^11_ 2 + W,; 
+ W,. ^ 
Equation (13) gives the means of calculating the water equivalent. 
Writing M;^, Mg for Wj + W.^. and Wg + W.^. respectively, we have 
^^2= “ . 
which, with (if), gives 
F'la ^^2”^ f 
~ ^ - ITq . 
^11 ^h ^ ^Pi 
* This does not introduce a, the heat developed by the stirrer, but this can be found by preliniinaiy 
experiments and due allowance made for it. 
