Page:Proceedings of the Royal Society of London Vol 1.djvu/403

Rh worms is merely an accompaniment. not an effect of the phenomenon; and that heat and electricity act merely like other stimuli upon the vital powers of the animal.

The author prefaces the account of his experiments and observations on the nature and properties of purulent ﬂuids, by an etymological disquisition concerning the origin of the word Pus, and the various senses which philologists may discover for the word 7rvos, be- sides the distinct signiﬁcation given to it by Hippocrates, of a thick, white, inodorous, uniformly smooth ﬂuid, which is contained in an abscess. From the etymology, Dr. Pearson next proceeds to the history of the several opinions that have been entertained respecting the formation of purulent matters, and of the characters by which different persons have endeavoured to distinguish real pus, from such purulent ﬂuids as ought rather to be considered as modiﬁcations of mucus. Since nothing appears to have been added since the date of Mr. Home's dissertation on pus, which was written in the year 1798E Dr. Pearson’s history concludes with an outline of Mr. Home's ac- count of the nature of pus. According to him, pus is composed of globules swimming in a transparent aqueous ﬂuid. The globules. on which its opacity depends, are formed subsequently to the secretion of the transparent ﬂuid. They are not soluble in cold water, like those of blood, but are decomposed by boiling water; and the ﬂuid in which they swim is not coagulable by heat, as serum, but is co- agulable by sal-ammoniac, which does not coagulate serum.

Dr. Pearson’s examination of pus is divided into six sections, of which the ﬁrst treats of the simple and obvious properties; and he distinguishes four diEerent kinds of pus,

1. The cream-like and equally consistent.

2. The curdy of unequal consistence.

3. The serous, or thin kind.

4. The thick, viscid, or slimy.

Of course, as he examines, under the name of pus. ﬂuids so dif- ferent from each other, he obtains results which differ accordingly in the qualiﬁes and quantities of their ingredients.

In the second section the agency of caloric is observed.

According to the author, all kinds of pus are coagulated between 160° and 165° of Fahrenheit. By continued heat the water is eva- porated, and there remains a dry brittle mass, amounting to about one seventh or one eighth of the original weight. By exposure to greater heat in a crucible of platina, the greatest part of this resi— duum was consumed, and there remained only the salts of the serum fused together. and amounting to Thth, “'mdth, or 1+udth, of the original quantity of pus employed.

These, says the author, consisted chieﬂy of muriate of soda, phosphate of lime, potash, with strong indication of carbonate of lime,