214 Prof. Davy on some further applications of 
But these two equations are not enough to precisely determine a, 
they lead to the 9-valued function 
Py 2 3 A os. 
? 7 g 7 af eo a 
2 — 4.4.4 his hating § 
VJ; +a/ 4. OF ate ae 4 * 97 
in order to precisely determine x, it is (as everybody knows) 
necessary to use the original equation ad= — * But seek for 
the solution as follows; viz. write e=ab(a+5), which gives 
8a°b?=—g, a®b?(a?+b*) =r, 
or what is the same thing, 
As ae ~3, Plat | ee hs sual 
these equations give v=ab(a+b), where 
3 a hoe ere 
a= ene Orie d = pan) — n/a son ee or f 
ay‘ ate ? 4g? * 3’ 
which is a 3-valued function only, ad in this case a not given. 
2 Stone Buildings, W.C., 
January 28, 186]. 
XXXIV. Onsome further applications of the Ferrocyande of Po- 
tassium in Chemical Analysis. By KymMunpd W. Davy, A.B., 
M.B., M.RILA., Professor of Agriculture and Agricultural 
Chemistry to the Royal Dublin Society*. 
| HAVE recently been engaged in making some experiments 
on the ferrocyanide of potassium or yellow prussiate of 
potash, with a view to extend its applications in chemical ana- 
lysis ; for though this important salt has already been applied to 
a number of useful purposes in analytical research, still my ex- 
periments have shown me that its use might be advantageously 
extended, particularly as a reagent in volumetric analysis, a form 
of analysis which has of late come into very general adoption, 
especially for technical purposes, on account of the great quick- 
ness and at the same time accuracy with which different sub- 
stances may by its means be determined. The principles upon 
which volumetric analysis depend are so well known, that I 
need not refer to them; and though it possesses so many ad- 
vantages over the older gravimetrical method, in which the dif- 
ferent substances are determined by weight instead of by volume, 
it yet has this drawback, that the preparation of the necessary 
standard solutions often takes considerable time, first, in order 
* Part of a paper read before the Royal Dublin Society, December 17, 
1860 ; and communicated by the Author, 
