(hi Vaccinatiofu 



A second order of facts which ought to be excluded from the 

 comparison, consists in observations of eruptive diseases, distin-* 

 guished by the name of the smallpox, but which from their 

 characters belonged evidently to the chicken-pox, or to some 

 anomalous eruption, which have but a faint resemblance in form 

 to the small-pox, but are in other respects quite different. Such 

 eruptions show themselves every day upon children who have 

 had the small-pox ; and when they appear before that disease, 

 they do not prevent it from infecting the patient. An attentive 

 observer can easily distinguish such eruptions. The small-pox 

 have a regular progress which cannot be mistaken ; and when 

 they are confluent they can be still confounded with other erup- 

 tions, which are usually exempt from all danger, and even from 

 severe illness. Every observation, then, which does not give us 

 the essential characters by which the small-pox is distinguished 

 from other eruptive diseases, and in which we do not find the 

 fever of the commencement of the disease, the eruption, the 

 suppuration, the fever of intumescence which accompanies it, 

 and the desiccation — every such observation cannot come into 

 comparison with the observations in favour of the present 

 question. 



There is a third order of facts which cannot be admitted into 

 the comparison of which w^e speak ; we mean those cases in 

 which a true small-pox makes its appearance during the time of 

 vaccination, at an epoch when we must suppose that the infec- ^ 

 fection was caught before the cow-ppx could exert its preventive 

 powers. This point has been discussed in the first report to the 

 Institute. We have already, in the memoir, given several 

 examples of it, in speaking of the eruptions and diseases 

 ascribed to the cow-pox. On this point Dr. Sacco has made 

 some curious experiments, to determine the precise time when 

 the small-pox may still appear after vaccination. Supposing the 

 cow-pox to appear on the 3d day after the puncture, the 

 inoculation for the small-pox performed between the 1st and 5th 

 day occasioned the appearance of the small-pox between the 7th 

 and 11th day. Inoculation performed on the 6th or Jth day 

 occasioned a slight inflammation of the part punctured, without 

 any general eruption. Either no pox appeared over the punc- 

 tures, or if they did they speedily dried up. Inoculation per- 

 formed from the 8th to the 11th day produced a slight alteration 



justly appreciated by the central committee of Paris, who voted to him owe 

 of their medals, has ascertained that one of the best methods of preserving the 

 cuw-pox virus is that thought of by M. Bretonneau, to introduce it into ca- 

 pillary tubes, and then to seal them hermetically. He has succeeded, also, 

 with the crusts, especiailj when fresh. Sut the success of these roethods has 

 never been so constant as when the matter is taken from one arm aad intro- 

 duced immediately into aaather. 



