i & Dr . Wollaston. 
107 
Experiment 1. 
“ After having satisfied myself, by trials made by some 
medical gentlemen upon themselves, that considerable doses 
of prussiat of potash might be taken without the least incon- 
venience, I gave to a young woman labouring under diabetes 
mellitus, five grains of prussiat of potash dissolved in water, 
and this was repeated every hour till she had taken thirteen 
or fourteen such doses. After the fifth dose, her urine, by 
the addition of a drop or two of a solution of sulphat of iron, 
turned blue instantly. At this period of the experiment, a 
blister was applied to her stomach, and after a few hours, 
whilst still taking the prussiat of potash, and whilst the urine 
strongly indicated its presence, the blister was cut and the 
serum collected. This serous fluid being, in the same manner 
as the urine, subjected to the action of a solution of sulphat 
of iron, did not suffer any change of colour in the least indi- 
cative of the presence of prussic acid. Yet the urine still 
remained capable of imparting a blue colour to solution of 
iron, fifteen hours after taking the last dose of the prussiat 
of potash. 
Experiment 2. 
“ The same person being soon afterwards put upon a course 
of ferruginous medicines, and having taken considerable quan- 
tities of sulphat of iron, an idea naturally occurred to me that 
the phenomenon might perhaps be reversed ; but upon adding 
prussiat of potash to the urine, no vestige of iron could be 
discovered, and the same attempt was repeated several times 
with the same negative result. 
P ‘2 
