206 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



THE COMPARATIVE ACTION OF I>BY HEAT AND SUIiPHUBOlJS 

 ACID IJPOIV PUTREFACTIVE BACTERIA. 



Pieces of woolen and cotton cloths and wadding were dipped in a 

 solution of putrefying flesh and slightly dried ; and after being shown 

 to be infected by causing discoloration and development of bacteria in 

 a Pateur solution, one portion was subjected to dry heat, and the other 

 to the influence of a definite quantity of sulphurous acid. When these 

 agents had oijerated for a certain time, the substances were brought 

 into a developing liquid and again observed. 



These experiments, which were conducted by Dr. Wermch, were as 

 follows : 



First. Fragments of the materials above referred to, treated as men- 

 tioned and dried, produced in sixteen experiments an exceptionably 

 rapid disturbance of the test liquid. In four experiments with wadding 

 this was somewhat retarded. It took j)lace most rapidly in tubes which 

 had been inoculated with woolen thread. 



Second. After inoculation with the material which had been exposed 

 one or two minutes to a dry heat of 284^ to 300° F., clouding took place 

 in four of eight experiments ; but only after from two to three days. 

 With material which had been exposed from ten to sixty minntes to ' 

 a heat of 230O-244'^ F., in five out of six experiments d development 

 of bacteria took place after the end of twenty- four hours. 



Third. Substances which were exj)osed five minutes to a heat of 257° 

 to 302° F. produced no infection whatever in ten experiments. The 

 test liquid remained clear for eleven days from the time of inoculation. 



Fourth. When the objects were exposed under a bell glass to the 

 action of a percentage, by volume, of 1.5, 2.2, and 3.3 of sulphurous 

 acid, in eight out of nine exi)eriments a bacterial clouding was devel- 

 oped in the sulphurized material, whether the application had continued 

 for one hour or twenty-two. 



Fifth. In fifteen experiments, in which sulphurous acid constituted 

 4.6 and 7.15 per cent., by volume, of the contents of the bell glass, the 

 introduction of the sulphurized material produced no cloudiness, when 

 the exj)eriment continued six hours and more. On the other hand an 

 exposure of 20, 40, 60, and 200 minutes was followed by the develop- 

 ment of bacteria. 



In conclusion, the fact was considered especially interesting that the 

 different fabrics gave up the infection concealed in them with different 

 degrees of rapidity, the woolen fiber the quickest, the linen less easily, 

 and the wadding with the greatest difficulty of all. 



