OXALIC ACID. 
§§ 728, 729.] 
549 
the specimen beside another in the same museum which illustrates the 
effect of the gastric juice in causing an after-death solution of a portion 
of the stomach, it was difficult to differentiate between the two. The 
mucous membrane has the same shreddy, flocculent appearance, and is 
soft and pale. The pyloric end is said to have been of a blackish colour, 
and no lymph was exuded. 
§ 728. The pathological changes by the acid oxalate of potash are 
identical with those of oxalic acid, in both, the gullet and stomach 
being nearly always more or less inflamed or corroded ; the inflammation 
in a few cases has extended right through into the intestinal canal; 
there are venous hyperaemia, haemorrhages, and swelling of the mucous 
membrane of the stomach. The haemorrhages are often punctiform, but 
occasionally larger, arranged in rows on the summits of the rugae ; some¬ 
times there is considerable bleeding. In the greater number of cases 
there is no actual erosion of the stomach, but the inner layer appears 
abnormally transparent. On examining the mucous membrane under 
the microscope, Lesser 1 has described it as covered with a layer which 
strongly reflects light, and is to be considered as caused by a fine preci¬ 
pitate of calcic oxalate. Lesser was unable to find in any case oxalic 
acid crystals, or those of the acid oxalate of potash. There are many 
cases of perforation on record, but it is questionable whether they are 
not all to be regarded as post-mortem effects, and not life-changes ; at 
all events, there is little clinical evidence to support the view that 
these perforations occur during life. In the case (mentioned ante) in 
which death took place by coma, the brain was hypersemic. The 
kidneys, as in the case of animals, show the white zone, and are con¬ 
gested, and can be proved by microscopical and chemical means to be 
rich in oxalates. 
§ 729. Separation of Oxalic Acid from Organic Substances, the 
Tissues of the Body, etc. —From what has been stated, no investigation 
as to the cause of poison, when oxalic acid is suspected, can be con¬ 
sidered complete unless the analyst has an opportunity of examining 
both the urine and the kidneys ; for although in most cases—when the 
acid itself or the acid potassic salt has been taken—there may be ample 
evidence, both chemical and pathological, it is entirely different if a 
case of poisoning with neutral sodic salt should occur. In this event 
there may be no congested appearance of any portion of the intestinal 
canal, and the evidence must mainly rest on the urine and kidneys. 
Oxalic acid being so widely distributed in the vegetable kingdom, the 
expert must expect, in any criminal case, to be cross-examined by 
ingenious counsel as to whether or not it was possible that the acid 
could have entered the body in a rhubarb-pie, or accidentally through 
sorrel mixed with greens, etc. To meet these and similar questions it 
1 Virchow’s Archiv, lxxxiii. 218, 1881. 
