On the Tempering o^Jron haTdened*by O/v/-.-,-/, "/'//. 461 



these situations. In one instance, in which the blood-vessels of the 

 brain were found to be much congested, inoculation of a tube of sloping 

 agar with a large platinum loopful of cerebro-spinal fluid, well spread 

 over the surface of the agar, resulted in the appearance of half a 

 dozen isolated colonies of a pure culture of the distemper bacillus. 



By heating a broth culture of the bacillus at 60 C. for half an 

 hour, and subsequently adding a small quantity of carbolic acid as a 

 preservative, a vaccine is obtained, which acts in similar fashion to 

 those devised by Haff kine and Wright for use in the prevention of 

 plague and enteric fever respectively. The vaccine may be standardised 

 after the manner originally suggested by Wright in connection with his 

 work on enteric fever. 



The dose must obviously vary according to the size of the dog, but, 

 as a guide, it may be mentioned that I have found, in three instances, 

 that the injection of 2 c.c. of the sterilised culture of the bacillus is 

 apparently sufficient to protect fox-terrier puppies weighing about 

 H kilos, against attack by distemper, while an unprotected puppy in 

 the same batch contracted the disease on introduction of an affected 

 dog. I find also that guinea-pigs can be protected in this way against 

 the effects of a dose of living culture, which would ordinarily prove 

 fatal in about forty-eight hours. As regards the exact length of time, 

 however, during which such protective effect may last, no definite 

 statement can as yet be made, but a series of tests on a large scale are 

 in process of being carried out by dog-breeders in this country, in 

 Germany, and in America. 



" On the Tempering of Iron hardened by Overstrain."* By JAMES 

 MUIR, B.Sc., B.A., Trinity College, Cambridge, 1851 Exhibi- 

 tion Eesearch Scholar, Glasgow University. Communicated 

 by Professor EWING, F.R.S. Received July 11, Read De- 

 cember 6, 1900. 



(Abstract.) 



It is well known that iron hardened by overstrain, for example, by 

 permanent stretching, may have its original properties restored again 

 by annealing, that is, by heating it above a definite high temperature 

 and allowing it to cool slowly. Experiments described in the paper, 

 of which this is an abstract, show, however, that if iron hardened by 

 overstrain be raised to any temperature above 300 C., it may be 

 partially softened in a manner analogous to the ordinary tempering or 



* The work described in this paper is a continuation of that already described 

 in a paper by the present author " On the Recovery of Iron from Overstrain," 

 ' Phil. Trans./ A, vol. 193, 1899. 



