214 
BRITISH PHARMACEUTICAL CONFERENCE. 
tigating the nature of the crystalline constituents of plants. It may assist u 
in extending our knowledge of the natural state of combination of the alk a- 
loids and organic acids ; it may demonstrate the presence of salts previous ly 
unknown, and may show that salts, hitherto only occasionally met with, are of 
common occurrence. Moreover, by showing the presence or absence or varia¬ 
tion in amount of a given crystalline constituent, it will help us in ascertaining 
the influence which variations in climate and soil have upon vegetables, will 
doubtless aid in determining more exactly the office of the various parts of 
plants, and, lastly, may throw light on the changes which go on at different 
periods of the life of a plant. 
ON THE PURITY OF FOREIGN IODIDE OF POTASSIUM. 
BY MR. F. C. CLAYTON. 
{Read at the Bath Meeting of the British Pharmaceutical Conference, September , 1864.) 
The results of an examination of a subject like the present may be most 
easily comprehended by means of a Table. 
[ 
French and German. 
English. 
I. 
II. 
III. 
IV. 
V. 
* 
VI.-IX. 
X. 
XI. 
XII. 
XIII. 
XIV. 
XV. 
Carbonate of) 
Potash ...I 
•7 
•31 
•7 
•2 
•15 
0 
•14 
•28 
0 
•11 
•3 
Sulphate of") 
Potash ...j 
Trace 
tr. 
tr. 
tr. 
0 
tr. 
tr. 
tr. 
0 
0 
tr. 
Iodate of) 
Potash ...) 
•8 
0 
0 
•7 
tr. 
0 
0 
0 
0 
0 
0 
0 
Chloride of i 
Potassium / 
1-56 
♦3 
'5 
1-5 
3-74 
tr. 
•52 
•31 
tr. 
•1 
•15 
Bromide of) 
Potassium j 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Moisture . 
1-1 
1-4 
2-5 
2-4 
•8 
1-2 
•9 
•6 
•5 
3-7 
1-75 
Iodide of) 
Potassium ) 
96- 
98-1 
96-4 
95-4 
95-3 
98-9 
98-4 
98-7 
99-5 
96-28 
97*8 
100-16 
100-11 
100-1 
100-2 
. 
99-99 
100-1 
99-96 
99-89 
100- 
100-19 
h-> 
O 
o 
For the sake of comparison, a few samples of English manufacture were ana¬ 
lysed and are represented by Nos. X.-XV. 
The methods employed for the estimation of the various constituents are as 
follows:— 
Carbonate. —Volumetrically, by means of very dilute sulphuric acid, 10 c.c. 
of which = *05 grm. K0,C0 2 , an addition of one drop of tincture of litmus 
being made previous to analysis. The quantity operated on was about two 
grammes. 
Iodcite. —Chlorimetrically, by treating a known quantity of pure iodate of 
potash with tartaric acid and iodide of potassium, and comparing with the con¬ 
taminated sample in a test tube of the same diameter, etc. 
Chloride .—About two grammes were dissolved in the smallest quantity of 
water, two c.c. of NO s added and then chloroform or benzole and more water. 
Agitate and repeat, adding the chloroform till it ceases to be coloured. The 
chlorine is left in the aqueous solution and may be estimated by the usual 
methods. 
Bromide .—Precipitate the iodide as subiodide of copper, filter, and treat the 
* Samples VI. to IX. were examined only for iodate and bromide. 
