252 MANUAL OF BACTERIOLOGY. 



to destroy the Staphylococcus pyogenes aureus, while 1-5000 

 is sufficient to restrain its growth (Slater and Rideal) . Its use 

 in a gaseous form as a house-disinfectant is by far the most im- 

 portant application at the present time. 



In vaporizing the gas many methods have been employed. 

 Simple evaporization of solutions without heat cannot be 

 relied upon, for the solid, polymerized paraformaldehyde is 

 easily formed under these circumstances. Better results can 

 be obtained with the aid of heat, although polymerization is apt 

 to occur unless evaporation is rapid. To produce the best 

 results it has been found necessary to use special forms of 

 lamps or generators for its production, a few of which are 

 mentioned below. 



Gotschlich* has carefully summed up the results obtained 

 with formalin and its various preparations. He finds that 

 while authorities agree in attributing very powerful inhibitory 

 action to formaldehyde, they fail to get very powerful germi- 

 cidal action. Even -^-Q^-Q-Q shows marked inhibition, and y-0-J-jnr 

 complete inhibition of bacterial growth in albuminous 

 media even, varying of course with different bacteria. But in 

 contrast to this 2.5 to 5 per cent, was required to kill the same 

 organisms. The action of formalin is greatly increased by heat- 

 ing. Anthrax spores were killed in one and one-half hours in 

 12.5 to 15 per cent, formalin at room temperature, in the same 

 solution they were killed in thirty minutes at 35 C., and in five 

 minutes at 52 C. Lysoform, a perfumed soap containing 

 formalin was found to be weak; septoform, a similar soap 

 preparation was found to be somewhat m >re powerful ; it has 

 the remarkable property of being more strongly germicid?! for 

 anthrax spores than for the pus cocci. Other proprietary 

 preparations were also found to be weak in germicidal power, 

 others again more powerful Acrolein which is allylaldehyde 

 is said to have greater germicidal power than formalin. 



*Kolle and Wassermann. Loc. cit 



