1 61 A Sketch of a History of Pus. 



dally promoted by the honorary rewards offered by severaf 

 associated bodies. Hence some improvements have been 

 made. But physicians were still continually complaining 

 or the disadvantage in practice, from the distinguishing 

 properties of pus not being satisfactorily determined; above; 

 all, for the purpose of judging in pulmonary diseases whe- 

 ther or not the sputum was purulent. In the year 177®> 

 the late Mr. Charles Darwin received the gold medal 

 from the yE>culapian Society at Edinburgh, for his sup- 

 posed discoveries of the criteria by which pus and mucus 

 are distinguishable. It was asserted that, water being ad-j 

 ded to a dissolution of pus in sulphuric acid, a precipitation 

 talffes place, but such a dissolution of mucus affords on the* 

 addition of water merely suspended flakes ; — that pus is 

 diffusible through diluted sulphuric acid, but mucus is; 

 not; — that these effects are also observed with water, or salt 

 water. In 1787, Dr. Brugman, in his Inaugural Disserta- 

 tion on Pus, among a number of other experiments, which- 

 I do not think necessary to be noticed, relates that dry 

 volatile alkali (carbonate of ammonia) with an equal quan- 

 tity of pus becomes viscid, semi-transparent and white? 

 that caustic ammonia partially dissolves it, and the rest 

 yields a very viscid fluid, but on adding water the whole is 

 deposited in a viscid state; — that all neutral salts thicken 

 pus, and still more so the earthy salts, and most of all the 

 metallic salts ;-^-that alcohol condenses it by uniting to its 

 aqueous parts, but neither coagulates nor dissolves it. But 

 previously to these experiments, Mr. Hunter had observed, 

 that pus is " coagulated by sal ammoniac" (muriate of 

 ammonia), which he, and subsequently Mr. Home, depend 

 upon, as affording a criterion between pus and other animal 

 fluids. Grassmayer is quoted by several authors for the 

 fact that pus is precipitable in a gelatinous state by caustic, 

 alkaline lixivium, but if mucus be present it is suspended; 

 The mistake in the fact that pus was highly putrescible, 

 was perhaps first exposed by my fellow-student Dr. Hendy, 

 h iwas subsequently confirmed by Mr. Home. Several 

 foreign authors, as Plenciz, Murray, Schroeder, Salmuth, 

 ^)ucsnay, either adopted subsequently, or coincided in, the 

 opinion that pus is a secreted fluid. Mr. Home's inge* 

 nious' Dissertation on Pus was published in 1788, audi 

 find ho accession of facts from that date up to the present 

 time. J J is wovk is valuable, not only for his own obser* 

 .vations, but for a just exposition of those of Mr. Hunter. 

 It is here attempted to be shown that f« pus is composed 

 of globules swimming in a transparent aqueous .fluid, yet 



that 



