It would appear, from the facts collected up to the present moment on this subject, that we are justified in considering, 1st, that mucus is a compound of albumen in a state of close combination with alkaline salts, and probably free alkali ; 2nd, that the artificial compound formed by the addition of alkalies and neutral salts to albuminous matter is essentially the same as mucus; 3rd, that the mucus globule is superadded to the viscous matter in the secretions of mucous membranes, and is in no way concerned in imparting the peculiar tenacious character to such fluids.
A great deal of trouble has been taken to devise chemical means of distinguishing tween pus and mucus, or to detect the presence of the former when existing combined in small proportion with the latter. No chemical method of inquiry can ever be applicable to this question : the microscope must be had recourse to for the detection of the pus globule, if the mucus be suspected to contain it in quantity so small as to escape casual nation. When pus is present, however, even in very small proportion to the mucus, its physical characters are so distinct that no chemical or microscopical tests can possibly be required. Considered as a means of proof,
the folly of using chemical tests is at once apparent when we recollect that the question as regards pus is entirely one of structure, and we cannot in reason use chemical tests to determine the presence or absence of a globule. When pus exists as a deposit in urine, we may easily distinguish it from the phosphates with which it is sometimes founded by adding an alkali, as recommended by Dr. Babington, in which case the deposit (which must be previously separated by cantation from the urine) assumes the glairy character of mucus, and thus shows its minous nature. As affording us a distinctive test, therefore, between these two substances, chemistry becomes useful ; but inasmuch as the addition of alkali to most forms of minous matter developes a mucous tenacity, the re-agent cannot correctly be called a test for pus. We become assured of the presence of pus by this reaction only, because previous experiment has shown that the phosphates and pus are the only two substances assuming a peculiar and similar appearance in the urine. ( G. Owen Rees.)