the Ferrocyanide of Potassium in Chemical Analysis. 219 
my method indicated a few hundredths of a part more of chlorine 
than either of those methods did, which may be accounted for 
by the unavoidable loss of a minute quantity of chlorine which 
takes place in those processes. 
In order to simplify the process, and render the calculation 
as short as possible, | would recommend for commercial valua- 
tions the following way of carrying out this principle :— 
Haying obtained a flat-bottom flask or bottle which will con- 
tain 10,000 grains of distilled water when filled up to a certain 
mark in the neck, make two standard solutions, the first by 
placing in the flask or bottle 1190 (or exactly 1189°97*) grains 
of the purest crystallized ferrocyanide of potassium (yellow 
prussiate of potash) reduced to powder, adding distilled water 
to dissolve the salt, and when this is effected, fillmg up with 
water to the mark; and having mixed the solution thoroughly, 
place it in a well-stoppered bottle. The second standard solution 
is made in the same manner, substituting for the ferrocyanide 
138°6 (or exactly 138°58) grains of bichromate of potash which 
has been purified by recrystallization and fused in a crucible at 
as low a heat as possible. Both these solutions will keep un- 
changed, and will answer for a number of determinations if they 
are preserved in well-stoppered bottles, and the ferrocyanide 
solution be kept, when not in use, excluded from. the light. 
Get a burette or alkalimeter capable of holding or delivermg 
1000 grains of distilled water, and divided into 100 equal 
divisions ; also two small bottles, one capable of delivering 1000 
grains, and the other 500 grains of distilled water when filled 
up to a certain mark on the neck of eacht, which may both be 
readily made by fillmg them with water, emptying them, and 
after they have drained for a minute or two, weighing into each 
the above weights of distilled water ; or, what will be sufficiently 
accurate for most purposes, pour from the burette into one 100 
divisions of distilled water, and into the other 50, and mark 
with a file where the fluid stands im the neck of each bottle. 
Having these all ready, take an average specimen of chloride of 
lime, and weigh out 100 grains of it, and make in the usual 
way a solution of it by trituration in a mortar with some 
* The above numbers are obtained as follows :—35'5 parts of chlorine 
are capable, as before stated, of converting 422°44 parts of the crystallized 
ferrocyanide of potassium into ferridcyanide; therefore 100 parts of the 
former will convert 1189°97 parts of the latter into the same compound. 
Again, as before observed, 1267°32 parts of the crystallized ferrocyanide 
require 147°59 parts of the bichromate of potash to convert them into the 
ferridcyanide; 1189-97 parts, therefore, will take 138°58 parts of that salt 
to produce the same cifect. 
+ Two small pipettes capable of delivering the above quantities would 
be found still more convenient, 
