152 
BRITISH PHARMACEUTICAL CONFERENCE. 
“ ON THE APPLICATION OF DIALY'SIS IN DETERMINING THE NATURE OF THE 
CRYSTALLINE CONSTITUENTS OF PLANTS. BY J. ATTFIELD, PH.D., F.C.S., 
DIRECTOR OF THE LABORATORIES OF THE PHARMACEUTICAL SOCIETY OF 
GREAT BRITAIN. 
\_Abstract .] 
“ Tlie author had dialysed a few plant-juices, the first that came to hand, and from 
each had obtained some of the crystalline constituents. The tops of the common 
potato yielded a crop of nitrate of potash, some cubes of chloride of potassium, hexa¬ 
gonal crystal not analysed, sugar, and an ammonia salt. The deadly nightshade gave 
nitrate of potash, an unknown magnesia salt in square prisms, sugar, etc. Pea-pods 
yielded only sugar. The common garden lettuce contained nitrate of potash, tetra- 
hedra of undetermined composition, sugar and ammonia. Cucumbers furnished 
sugar, ammonia, and sulphate of lime. The cabbage also furnished sulphate of lime 
and ammonia. Stramonium contained so much nitrate of potash, that dried portions 
quite deflagrated on being ignited. 
“ From these experiments the author thought the proposed application of dialysis 
promised to be of great service, directly and indirectly, in investigating vegetable 
physiology.” 
In reply to Mr. Groves, who inquired if any of the alkaloids had been detected, the 
author said that traces of crystalline principles which were not referred to any par¬ 
ticular substance were seen, and these possibly were natural salts of the alkaloids. 
Much larger quantities of material would be needed for their discrimination, and even 
then the relatively large amount of the colloid as compared with the alkaloid would 
make the complete isolation of the latter a doubtful problem. 
Dr. Edwards was disappointed in the results of the application of dialysis to toxi¬ 
cology, from which much had been expected. If the process was continued for a 
length of time, portions of the colloid were transmitted through the membrane, and 
vitiated the result. 
Mr. Brough observed that such a condition was inevitable, since there was no 
absolute line of demarcation in the transfusion of colloids and crystalloids. 
“ ON THE PURITY OF FOREIGN IODIDE OF POTASSIUM. BY F. C. CLAYTON. 
\_Abstract.~\ 
“ The high price and large consumption of this article has made it one which the ma¬ 
nufacturer has special temptations to adulterate. Of late years very large quantities 
of foreign make have found their way into our markets, giving rise to keen competition, 
which, in the case of drugs, is often far from improving their quality. From these 
considerations we might still expect to find much that is impure, but the results de¬ 
tailed below lead us to a different conclusion. The impurities of iodide of potassium 
are bromide and chloride of potassium, and sulphate, iodate, and carbonate of potash. 
Moisture in excess is also to be considered an impurity, for, besides giving the sample 
a greater liability to deliquesce, it shows an article of imperfect manufacture. The 
first-mentioned adulterant, though it has at times been frequently used, lias in none 
of the 15 samples experimented upon been found, and the second only in quantities 
from 3‘7 per cent, down to minute traces. Sulphate was never found in ponderable 
quantities, and iodate in only 3, all of which, however, were of foreign manufacture. 
(Several English samples were analysed for the sake of comparison.) In these three 
cases it never amounted to 1 per cent. Carbonate, though more generally present, 
never amounted to 1 per cent., generally much under this. From these results, it will 
be seen that the iodide of potassium now in the market is practically pure, the per¬ 
centage in all the samples being over 95.” 
Mr. D. Hanbury remarked that sulphate of iron was a much more delicate test for 
the presence of carbonate of potash than was lime-water. If so examined, he thought 
that few samples w’ould be found free from carbonate. Iodide of potassium had 
sometimes been prescribed in combination with several saline sulphates at once, as 
soda, magnesia, etc. In such cases, no trace of carbonate was admissible, or a precipi¬ 
tate is formed. 
In reply to a remark that syrup of iodide of iron would also be decomposed by 
