The glands secrete hippuric acid which passes from the pericardium into the renal organs.
For this purpose the urine is concentrated and the hippuric acid precipitated by the addition of hydrochloric acid; it is then filtered and boiled for some time with concentrated hydrochloric acid, when it is hydrolysed into benzoic and amido-acetic acid.
The acid itself is a powerful antiseptic. When administered internally, it causes the appearance of hippuric acid in the urine.
An improved method of preparation was found in the use of hippuric acid, which reacts with hydrazine hydrate to form hippuryl hydrazine, C 6 H 5 [[Conh Ch 2 Conh Nh]] 2, and this substance is converted by nitrous acid into diazo-hippuramide, C 6 H 5 [[Conh Ch 2 Co Nh N 2.0h]], which is hydrolysed by the action of caustic alkalis with the production of salts of hydrazoic acid.
In the history of polarized light microscopy, one of the most popular chemical compounds studied was hippuric acid.