DETECTION OF POISON IN THE URINE. 121 
medicine or as it exists, combined with potash, in sorrel, it 
was afterwards found in the urine, forming crystals of oxa- 
late of lime. Dr. Letheby had found it in combination with 
urea. The experiments on the mineral acids were evidences 
of the remarkable depurating action of the kidneys, as 
mentioned by German writers; but before we could judge 
of the value of these experiments, the data upon which they 
were made must be examined. He had no doubt of the 
accuracy of these researches, for it must be remembered 
that sulphuric and muriatic acids existed in the urine ; the 
former becoming greatly increased if the personate mustard 
or other articles containing sulphur. He had been a little 
surprised to hear that the mineral acids in a free state were 
so soon detectable in the urine; for though it was mentioned 
in books as possible, he had repeatedly tried to detect it, 
and had been vexed to find how different were the results 
to those he had expected. He might, indeed, observe, that 
he had never succeeded in making urine acid by the exhi- 
bition of the acids, except by the benzoic. He had given 
the sulphuric and nitric acids in cases of alkaline urine for 
weeks together, but had never succeeded in making that 
fluid acid. One of the facts stated in the paper was of a 
startling character, viz., that from three to five grains of 
arsenious acid might be safely taken into the stomach if the 
kidneys were stimulated to diuresis, as it would be carried 
off by this channel. He could not understand how this 
could be, unless, indeed, there was some short road to the 
kidneys not at present known; for the arsenic, before it 
reached these organs, must be absorbed into the circulation. 
It was difficult to understand how escape from the poison 
was effected. The experiments respecting the absorption 
of the metallic poisons confirmed the experiments of the 
best French chemists. His experiments, also, respecting 
the presence of antimony in the urine, from poisoning by 
that agent, confirmed the views of others. 
Dr. Snow said that the difficulty of removing an alkales- 
11* 
