112 Disinfecting Powers of Incredsed iemperatures. 
Il. That the infectious matter of eow-pock is rendered inert, by 
a temperature not below 140° Fahrenheit ; from whence it was in- 
ferred that more active contagions are probably destructible, at tem- 
peratures not exceeding 212°. ‘This proposition it was obviously 
within the reach of the experiment to determine. But I had intend- 
ed to have resigned the inquiry, to those who are engaged in the 
practice of medicine, as more within their province than my own ; 
when the appearance of malignant cholera at Sunderland determined 
me immediately to extend the investigation. If that disease be com- 
municable from one person to another, there appeared ground for 
hope that any new facts or principles, respecting contagion generally, 
might be brought to bear upon this particular emergency. If chol- 
era should be proved not to be so communicable, there still would 
remain many infectious maladies, to which any newly acquired 
knowledge of the laws of contagion might admit of beneficial appli- 
cation. 
Of diseases generally allowed to be contagious, I could obtain ac- 
cess to two only, typhus and scarlatina. ‘The former malady does 
not, however, answer to all those conditions which are required to 
render it a fit subject of experiment. It is less distinctly marked, 
than many other diseases, by characteristic appearances ; and it is 
judged to exist, from a collection of symptoms, each of which is oc- 
casionally wanting, and each of which, when present, admits of 
such an infinite variety of shades, as to render its discrimination ex- 
tremely difficult and uncertain. But a still stronger objection to ty- 
phus, as a source of evidence on this subject, is, that by no inconsid- 
erable number of writers it is denied to be contagious at all. On 
this topic a controversy has been carried on, into which I decline to 
enter. My own conviction, founded on very extensive observation 
of the disease during more than twenty years of. private practice, 
and still more as physician to the Manchester Infirmary, Dispens- 
ary, and Fever-wards, is that, under certain circumstances, typhus is 
decidedly contagious ; although by strict attention to cleanliness and 
to free ventilation, the effluvia issuing from the sick may be so dilu- 
ted and carried off, as to be rendered almost harmless. 
My determination to reject the contagion of typhus as a subject of 
experiment was, however, changed, by learning from Mr. Johnson, 
ihe resident clerk of the Fever-wards in this town, that there was at 
that time in the house a singularly well-marked case of the disease. 
The physician also, to whose charge the patient (a female, et. 19) 
