1910. | Hydrochloric Acid in the Gastirie Tubules. 73 
reaction as late as 20 hours and in the eighth micturition after ingestion 
of the ferrocyanide of. potassium. 
A change, such as this recorded by Combemale and Dubiquet, in the 
potassium salt would not prohibit the occurrence of the Prussian blue 
reaction with certain of the iron salts, but would be absolutely prohibitive 
to any such formation with ammonium ferric citrate, for if a solution of this 
salt is mixed with one of potassium ferricyanide, the colour of the fluid 
remains brown, and becomes olive brown on the addition of hydrochloric 
acid, 
On the addition of hydrochloric acid to the urine of the animals personally 
investigated (dogs, rabbits, and guinea-pigs), the Prussian blue reaction 
occurred in almost every case, thus proving the presence of unchanged 
potassium ferrocyanide, as well as that of the iron salt. 
In cases of exception to this rule, proof of both the salts having existed in 
the body in an unchanged condition was furnished either by the presence of 
Prussian blue on the surface of the gastric mucosa, or by the occurrence of 
the reaction in one or other of the tissues treated after removal from the body 
with dilute hydrochloric acid, and tests were not made to ascertain which salt 
was lacking in the urine. The absolute exception, that is, entire disability to 
obtain the Prussian blue reaction in the urine, occurred in a dog and in a 
rabbit in which suppression and retention of urine were respectively 
observed. In the case of the dog (see Table, Dog 1), a very small quantity 
of urine was voided shortly before death, 34 hours after the beginning of 
the experiment, and the bladder was found to be empty at the post-mortem 
examination, while in the case of the rabbit (Rabbit 5) no urine, as far as 
known, was voided during the 253 hours of the experiment and the bladder 
was found enormously distended, but the bladder tissue in this case became 
slightly blue in the hydrochloric acid alcohol fixing solution. for the 
amount of solution injected see Table, Dog 1 and Rabbit 3. In the case of 
Rabbit 2, the Prussian blue reaction was obtained during the first day of 
the experiment, after 17 c. ems. of the injection fluid had been administered ; 
but it could not be obtained in the urine of the bladder at the time of 
death, 30 hours after the first and 24 hours after the last injection, when 
the total quantity of fluid injected had amounted to 37 c. cms. 
The earliest time that the Prussian blue reaction was obtained in the voided 
urine was 1} hours after the beginning of the experiment (Rabbit 6), A 
few minutes previous to this micturition, the rabbit had received the third 
injection of 11 c. ems., two others of the same amount having been given 
during the first hour of the experiment. The reaction at this time was faint, 
but was more marked in the urine voided three-quarters of an hour later. 
