HYDRARTHROSIS Or THE KNEE. 
48 5 
element present, as in phlegmonic inflammation, inflamed 
and irritable sores, &c., we make use of sedative agents, so 
as to diminish the supply of blood ; in other words, to lessen 
the quantity of oxygen sent to the part. In this way it is 
supposed that suppuratives produce action, and lessen the in- 
flammation of the diseased part. They abstract from it 
oxygen. Thus, if we employ a poultice, this remedial agent 
quickly takes on the acetous fermentation, and to do so it 
must absorb oxygen, which it does, from the inflamed part. 
Or, if we apply the compounds of turpentine or creasote here 
we have a preponderance of the electro-positives, namely, of 
carbon and hydrogen, which also combine with oxygen. 
Thus on chemical principles we may be guided in the 
choice of our local remedies ; avoiding such as contain 
electro-negative agents when we wish to dimmish action, and 
selecting such when we wish to excite action. 
HYDRARTHROSIS OE THE KNEE, TREATED BY TAPPING 
AND IODINE INJECTIONS. 
We are induced to refer to this mode of treatment, adopted 
by Mr. Erichsen, of the University College Hospital, as we 
consider it might prove suggestive. 
“ Puncturing the joints, the knee especially, in hydrops 
articuli has not been much, if at all, resorted to by British 
surgeons, although their attention has been frequently drawn 
to its practice by M. Malgaigne. The results of this practice 
in his hands, however, have not been such as to afford 
encouragement for its employment. This want of success 
led Bonnet, of Lyons, to try the effects of injection with 
iodine, similarly to the method employed in hydrocele, and 
so satisfactory did this turn out that many other French sur- 
geons of note followed in his wake, and Velpeau, Jobert, and 
others, confirmed the value and efficacy of this plan of treat- 
ment by the success which attended it in their hospital prac- 
tice. Still a reluctance was evinced to adopt it in this 
country, until the notice of the profession was again attracted 
to the subject by the publication of a series of cases by Dr. 
Macdonnell, of Montreal, in which the results were so satis- 
factory and conclusive as to leave no longer any doubt of its 
efficacy when adopted with ordinary precautions. It is pro- 
bable that it would have been resorted to earlier were it not 
for the fact, pointed out by Dr. Macdonnell, that it was 
