Sect. IV. From these experiments it follows, that 100 parts of euphorbium are composed of Water Woody matter Resin Loss 5 Observations and Experiments on Pus. PEARSON, M. D. F. R. S. (Phil. Trans. Part II. 1810.) By GEORGE CHEMICAL writers vary in their statements of the properties of pus; and they consider that a further investigation is requisite for the purposes of science. Physicians confess that, in numerous cases, they cannot form a satisfactory judgment of the nature of diseases, on account of not being able to determine what is, and what is not purulent matter; likewise probably, on account of the existence of different kinds, or varieties, at least, of this substance, afforded by different disorders. I beg leave, therefore, to submit to this learned Society, my own observations, experiments, and reasoning on this animal matter. SECTION I. Simple and obvious Properties. The different kinds of fluid, commonly considered to be pus, may be distinguished by the following titles: I. The cream-like and equally consistent. IV. The thick, viscid or slimy. 1. A pint of the first sort was taken out of the pericardium, after a fatal inflammation of the heart, in St. George's Hos pital, and obligingly sent to me by my colleague, Dr. E. N. Bancroft. The colour was yellowish-the smell was fleshy when warmed-it was smooth and unctuous to the touch. 2. The specific gravity of two different portions, was as 1630 and 1633, that of distilled water being 1580; each sub stance stance being of the same temperature. Serum of the blood of different patients was found at the same time to be 1626, 1627, and 1630. Accordingly, the distilled water being 1000, the pus is 1031, and 1033, and the serum is 1029, and 1031. 3. After twelve hours repose, about two ounces by measure of a limpid fluid having appeared on the top, it was decanted from off the opaque purulent fluid; which was become thinner in the upper part of the vessel containing it, and thicker in the lower than before. 4. On further repose, it did not become offensive so soon as a portion of the same pus mixed with a little blood, nor as serum alone. 5. This pus neither indicated acidity nor alkalescency to the usual tests, viz. turnsole paper, tincture of red cabbage, Brazil-wood paper, and turmeric paper. I have, in other instances sometimes, observed acidity to be indicated by turnsole paper; but in none alkalescency, so long as the matter remained without fœtor. 6. Being examined under the microscope, when duly diluted with distilled water, innumerable spherical particles were seen, which did not appear altered in figure, nor diminished in number by extreme dilution; that is, they did not appear to have been dissolved. II. A pint of pus of the second kind, vis. curdy, was afforded by a psoas abscess. The colour was brown. It felt knotty. On pouring from one vessel to another, the curdy masses were manifest, and of various sizes, from that of a pin's head to a hazel nut. It was more viseid than the former, and of a little greater specific gravity. On standing, a limpid fluid appeared upon the top, as in the first kind, but in smaller quantity. Globules were seen with the microscope, but also a number of irregularly figured larger masses. Putrefaction took place sooner than in the former kind. In other properties, this pus was similar to the first kind. III. Serous thin pus. It was produced by a fatal inflammation of the peritoneal coat, without ulcer, and taken out of the cavity of the abdomen. A good deal of serum was also effused, of which the pus was a deposit. It was not much thicker than milk. To the feeling it was not at all unctuous. The smell was slightly offensive. On standing twenty-four hours a sediment appeared, occupying only one. half the full vessel, under a whey-like liquid. Putrefaction took place sooner than in either of the two former kinds. The specific gravity was the same as that of the first sort. In other properties it was similar to the cream-like pus above distinguished. IV. A pint of the viscid pus was obtained from an abscess among the muscles of the thigh. If I had not had entire confidence in Mr. Brodie's accuracy, who was so obliging as to attend to my request, on this and many other like occasions, I should have supposed, that this was expectorated matter, it so exactly resembled in its simple properties, the ropy kind, described in a paper on expectorated matter. Phil Trans. 1809, P. II. p. 317. The appearance was not quite uniform, there being semitransparent masses in small proportion, mixed with the perfectly opaque white matter. It was almost inodorous. To the touch it was quite smooth. The specific gravity was nearly that of the second kind of pus. On standing 24 hours, about one ounce measure of limpid fluid rose to the top of the whole mass. Putrefaction did not take place so soon as in expectorated matter of the same consistence. The examination by the microscope manifested innumerable spherical particles among leafy masses, and numerous particles of irregular forms. The simple properties were otherwise similar to those of the other sorts of pus, above distinguished. Many other differences of purulent matter are universally recognized; but they are either varieties of the four kinds already named, or the differences depend upon the obvious mixture with adventitious substances; such as the red part of the blood, coagulated lymph, serum, putrefied matter, fibrous and membranous masses, calculi, &c. : therefore, I deem it useless to describe them. SECT. II. Agency of Caloric. 1. The above kinds of pus coagulated like serum of blood, into a firm, uniform, soft solid, at the temperature of 165o. completely.; but partially at 160° of FAHRENHEIT's ther mometer. 2. The decanted limpid fluid from pus, Sect. I.—I. II. III. IV. coagulated completely into a firm uniform mass, like serum of blood, at 165o, but it became opaque and thickened at 160o. By pressure on the firm curd thus produced, a watery liquid was separated, which on due evaporation did not give a jelly, but was coagulable like the decanted liquid just mentioned. The thick opaque matter, after decanting the limpid fluid, coagulated as before said, into a firm mass at 165°. 3. Each 3. Each of the above four kinds of pus being evaporated to dryness, left in no case less than one tenth of its original weight, nor more than one sixth; but most frequently one seventh, to one eighth of brittle matter. The smallest proportion of residue was left by the third, or serous kind; the largest, by the 2d or curdy. These residues generally be came rather soft, especially those of the third, or the serous kind, after exposure to the air. 4. The opaque part of pus after separating the limpid fluid afforded on evaporation about to more of brittle residue, than an equal weight of the pus itself; and it remained hard on exposure to the air. The limpid fluid evaporated to dryness, yielded about one tenth of brittle residue; which grew moist, and sometimes deliquesced, on exposure to the air. 5. The brittle residues above mentioned (3), being exposed to fire in platina crucibles, flamed for some time, emitting a very offensive, pungent, empyreumatic smell; the uninflammable residue being kept in a state of ignition for a longer period, what remained at length was fused readily from the serous, viz. the third kind of pus; but in the cases of the other exsiccated residues of the 1st, 2d, and 4th kinds of pus, they barely were melted, or only became soft and claggy. The fused residues from the serous pus amounted to to of the exsiccated pus; and toto of the ori ginal purulent matter. Those from the second kind, the curdy, amounted to to of the dried matter, and to to of the pus itself. The fused masses from the 1st and 4th kinds of purulent matter, afforded intermediate quantities of melted matter between those just mentioned. 6. The fused residues (5), being treated in the manner described in a former paper, Phil. Trans. 1809. P. II. p. 326 329, I found they consisted chiefly of muriate of soda, phosphate of lime, and potash; with strong indications of carbonate of lime, and a sulphate; besides traces of phosphate of magnesia, oxide of iron, and vitrifiable matter, probably silica. On a reasonable calculation, it appeared, that in the serous kind of pus, the muriate of soda amounts to from one and a half, to two per 1000; the phosphate of lime to one, to one and a half per 1000; the potash to one half, to three fourths of a part in this quantity; and the other matters together, to half a part in 1000. In the curdy matter, the second kind, the muriate of soda amounts to three fourths of a part, to one in a 1000; the phosphate of lime to one; the potash to less than one half; and the other matters united, to half a part in a 1000. The first kind of pus, the creamlike, and the fourth, the viscid, afforded from the melted re(No. 146.) sidue, Pu sidue, the same substances as the serous kind, excepting a somewhat smaller portion of muriate of soda, and potash. 7. The brittle residues of evaporated pus, after decanting the limpid fluid (4), being treated with fire as above related, the remaining matters were melted with more difficulty, and less completely, and contained a smaller proportion of muriate of soda and potash than the original pus. 8. The decanted limpid fluids (4), being evaporated to dryness, these residues were exposed to fire. They were melted, and then afforded a larger proportion of muriate of soda and of potash, than the pus itself; but with the same proportion of the other saline and earthy sub stances. SECT. III. Agency of Water. 1. After decanting the limpid fluid from off half a pint of the four kinds of pus as above related, (Sect. I.) three ounces measure of distilled water were mixed with each of them. After 48 hours repose, a limpid fluid of nearly the quantity of two ounces by measure, was seen forming an upper stratum to the pus. It was decanted for examination. (a) On exposure to fire it became turbid like milk, as soon as the temperature was elevated to 165°, but did not become thicker at a greater elevation. (b) On evaporation to dryness, the residue amounted to about one fifteenth of the weight of the liquid from the serous pus, and to one twentieth from the three other kinds; in place of about one tenth, as from the first decanted liquid, (Sect. I. 4); and as from serum of blood. The residuary matters were of the same kind as those above described, Sect. II. 2-6. (c) Three ounces measure of distilled water having been again mixed, with each of the four kinds of pus, and in 48 hours, two ounces measure of decanted limpid fluid from each, having been evaporated to dryness, residues of the same kind, in the same proportions, and in nearly the same quantities as before, were obtained (b). These decanted fluids became nearly as turbid as the former, on raising their temperature to 1650. (d) Distilled water was added a third time in the quantity of eight ounces by measure, to each of the four parcels of pus under examination, and after 48 hours repose, six ounces of limpid fluid were poured off from each of them. At the temperature of 165o, the decanted fluids became turbid; that of the serous pus more so than the others. On evaporation to dryness, a much smaller quantity of residue was obtained than |