Appendix. 397 



kind of infectious matter which assumes a tangible form, and can in 

 that form be submitted to experiments; and which admits also of 

 being afterwards tested by justifiable trials on healthy persons. Noth- 

 ing presented itself to me, on consideration, so well adapted to fulfil 

 all these conditions, as the matter of cow-pock. On mentioning my 

 views to Mr. Roberton, one of the surgeons of the Manchester Ly- 

 ing-in Hospital, he obligingly supplied me with vaccine lymph, taken 

 from pustules of unequivocal character ; and after the lymph had 

 feeen subjected to high temperatures, he directed the insertion of it 

 to be made, in the usual way, into the arms of healthy children. The 

 trials were conducted, and the results registered, by Mr. Gee, the 

 House-Apothecary of the Hospital. 



1. Vaccine lymph, dried at the temperature of the atmosphere on 

 small bits of window-glass, was exposed to a heat of 180° Fahren- 

 heit during four hours. Three healthy children of proper age were 

 inoculated with this matter without any effect ; but being afterwards 

 vaccinated with fresh matter, they all took the disease. 



2. Lymph heated, during the same period, at a temperature vary- 

 ing from 120° to 140°, generally 130°, was inserted without effect 

 into die arms of two healthy children, who were afterwards success- 

 fully vaccinated with recent matter. 



3. Four pieces of window glass, on which recent vaccine lymph 

 was placed, were heated during intervals varying from two to three 

 hours, at a temperature never below 160°, nor above 165° Fahren- 

 heit. The trials were judiciously varied by Mr. Gee, by inserting 

 each specimen of the matter which had been dried, into one arm 

 only of a healthy child ; while into the other arm of the same child 

 recent matter was inserted. In every instance, the heated matter 

 proved inefiicient; while the matter which had been dried at the 

 temperature of the atmosphere produced a satisfactory pustule. 



4. For the sake of obtaining a sufficient number of instances, I 

 requested Mr. Marshden, House-Surgeon of the Manchester Royal 

 Infirmary, to make trial of some genuine vaccine lymph which I had 

 received from him, and had then submitted to heat. One specimen 

 had been placed two hours in a steady temperature of 150°; a se- 

 cond four hours in the same temperature ; a third two hours, and the 

 fourth four hours, in the temperature of 172°. In no one instance, 

 did any of these specimens, when inserted in the usual manner, pro- 

 duce the vaccine pustule. 



5. Descending in the scale of temperature, another portion of vac- 

 cine lymph was exposed to an uniform heat of only 120° Fahrenheit 



