RESEARCHES INTO THE CAUSES OF BLINDNESS. 459 
servable on the transparent cornea, or else a softening of this mem- 
brane, attended with swelling. The treatment employed was at 
first that which we have already described; but, at the expiration 
of three weeks, seeing no symptoms of amendment, we applied 
anodyne collyria and setons in the chest, and gave purgatives. 
When the disease began to give way, we again had recourse to 
solutions of sulphate of zinc as a lotion, and mercurial ointment 
rubbed in, which effectually put a stop to the morbid secretions that 
had taken place. 
Apropos to treatment. We must relate a peculiarity, which 
proves that these affections acquire a certain manure d'etre from 
the causes which give rise to them, and which the same thera- 
peutic means cannot always destroy. An example will serve to 
explain our meaning more clearly. 
In many of the physical lesions of the eyelid or globe of the 
eye, such as those resulting from a blow, a bite, the introduction 
of some foreign body, & c., accompanied by violent sympathetic 
re-action on the organ, we have found useful crystallized ni- 
trate of silver (1 grain to 416 grs. of water). We had therefore 
hoped by the same means to cure this purulent ophthalmia ; but to 
our surprise it only aggravated the symptoms, although not em- 
ployed until the inflammatory phenomena were beginning to 
subside. 
The causes of this ophthalmia were quite evident. It was 
brought on entirely by the exhalations of those miasmata, the per- 
nicious effects of which were augmented by alternate rain and 
heat. It is an important fact, which proves beyond the shadow of 
a doubt that this etiology is well founded, that the horses chiefly 
attacked were those inhabiting the stable which we have above 
described as being nearest to the source of these deleterious fogs. 
Out of the twenty-eight which it contained, twenty were at- 
tacked; only six in the long northern stable, and but one in that 
facing the south. Nor was the influence of these effluvia confined 
to the horses : it extended itself to the men lodged in those rooms 
immediately over that stable nearest the river : many of them were 
seized with fluxion of the blood, which shortly became complicated 
with typhoid fever. We are indebted for some portion of this in- 
formation to M. Froment, surgeon-major. 
A chemical analysis of the atmosphere would, undoubtedly, have 
demonstrated the existence of some foreign matters, strangers to its 
natural constitution ; but not having the means of effecting this 
delicate operation at our command, we had recourse to the method 
employed by Rigaud de l’lsle in the marshes of Languedoc, and 
by M. Boussinguault in the islands of South America, which con- 
sisted in condensing the dew by laying a plate in a meadow, and 
