112 Disinfecting Powers of Increased Temperatures. 
II. That the infectious matter of cow-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 —_ in the 
practice of medicine, as more within their province than own 5 
when the appearance of malignant cholera at Sunderland aad 
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 — 
might be brought to bear upon this particular emergency. 
era should be proved not to be so communicable, there still = 
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 BSE: 
than many other diseases, by characteristic appearances; and it 
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 a 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 sieyaiclin 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, 
the re pees clerk of the Fever-wards in this town, that there was at 
n the house a singularly well-marked case of the disease- 
The icin also, to whose charge the patient (a female, zt. 19) 
