MICHIGAN ACADEMY OP SCIENCE. 179 



The separate organisms were exposed on sterilized silk threads, 

 squares of muslin and filter paper. These were thoroughly soaked in 

 a suspension of the organisms to be tested, and then transferred by 

 sterile forceps to a sterile Esmarch dish. The sets of specimens in the 

 different experiments were allowed to dry, for a definite length of time 

 under nearly as possible the same conditions as to temperature and 

 atmospheric moisture. This part of the general technic was strictly 

 adhered to; first, because of the marked difference in resistance of 

 moist and dry specimens; secondly, because the health officer in his 

 disinfection work usually encounters infectious and contagious mater- 

 ial in a dry state. A room containing 1000 cu. ft. was used for these 

 experiments, the average temperature of which was 15% C. 



The first set of specimens were exposed to the available formalde- 

 hyde derived from 1000 cc of formalin, this being evolved by the 375 grms 

 of KMnO^. The result of this experiment shows that the organisms 

 of diphtheria, pneumonia, anthrax and typhoid did not survive after one 

 hour exposure. Subtilis and pyocyaneus did show growth after an 

 exposure of eight hours. Colon and S. pyogenes alb. showed no growth 

 after two hours. To get the comparative value between this method 

 and the Novy generator method, a set of specimens as nearly alike 

 those used in the foregoing experiment as possible were exposed to 

 1000 cc formaldehyde distilled into the room by the Novy generator. 

 By this method only two organisms subtilis colon showed growth after 

 one hour exposure. 



The results of the two foregoing experiments clearly demonstrate that 

 the ''KMoNj^ process" is less effectual than the procedure followed out 

 by the Novy generator. In the former the organisms of subtilis and 

 pyocyaneus survive after an exposure of eight hours while by the 

 distillation process one gets no growth after one hour exposure. 



If the same set of organisms are exposed to the available formalde- 

 hyde jn 750 cc of formalin and 200 grms KMnO^ it is found that sub- 

 tilis colon and pyocyaneus survive for at least 12 hours, while diph- 

 theria and pneumonia show no growth after six hours; anthrax none 

 after four; typhoid and streptococcus after three hours shows no 

 growth. In this experiment cholera showed no growth whatever. 

 Using 750 cc by the Novy process one gets practically the same romilts 

 as were gotten with 1000 cc. So it can be plainly seen that the relat- 

 ive value of the two methods with 750 cc. of formalin differ quite mark- 

 edly, even more so than when 1000 cc. were used. 



When smaller amounts were employed it was found that there was 

 even a more marked deviation between the efficiency of the two processes. 

 And by a comparative study of the accompanying records one finds 

 that very similar results are gotten in the two methods by using from 

 150 to 300 cc. of formalin by the Novy generator method and 1000 cc. 

 by the KMn04 process. 



From the foregoing results the following conclusions can be drawn : 

 For thoroughness and efficiency the "KMn04 method" is not as useful 

 as the distillation method. In other words, an equal amount of formalin 

 being used in the two methods, one finds by the tables that the organ- 

 isms of the same kind when exposed to formaldehyde liberated by the 

 KMnOi method survive an exposure of much longer duration than ones 

 which were exposed to formaldehyde which was generated bv the Now 



