146 NINTH REPORT. 



formaldehyde destroyed is very small, as McClintic showed that the amount 

 of gas in his test rooms was substantially the same as where an equivalent 

 amount of the disinfectant was liberated by the autoclave, etc. 



The following figures obtained from some of our experiments and from 

 Dr. McClintic 's results will convey a good idea of the exact amount of for- 

 maldehyde absorbed in the reaction and that liberated as gas. Computing 

 from Dr. McClintic's formula, we find the amount of formaldehyde necessary 

 to cause a complete reaction in the permanganate taken by using the follow- 

 ing equation 



4 K Mn04 : 3 HC OH :: weight of permanganate used : X, or 628 : 90 :: 

 240 : X. 



X = 34 grms. formaldehyde used, that is, 85 Cc of the formaldehyde 

 would be used in the reaction, and the remainder, 395 Cc, would be driven 

 off into the room. 



.To verify these results we made trial experiments and weighed the ma- 

 terial before and after the reaction. 



Weight of formaldehyde. . .' 510 grams. 



Weight of pail 992 '' 



Weight of briquettes 281 " 



Total 1783 " 



Weight of pail and residue after reaction 1432 " 



Loss during reaction 351 " 



^o 



Weight of moisture in residue 43 " 



'to 



Loss and moisture 394 " 



Thus accounting for all but 1 gram of material that would be driven off, 

 as shown by Dr. McClintic's formula. 



Practically it is found that in the ordinary commercial 40% formalde- 

 hyde solution 38% is available by the autoclave method, while with this 

 method we can expect 33^%, which does not differ greatly from the other, 

 and even this apparent advantage in the autoclave method is more than 

 counterbalanced by the very rapid liberation of the gas, which makes for 

 very thorough disinfection the end sought by sanitarians. 



The public is becoming more thoroughly enlightened as to the necessity 

 of disinfection, and Health Boards are demanding that the most efficient 

 sanitary precautions shall be taken to limit the spread of the infectious 

 diseases. Nothing has been discovered that will satisfactorily take the 

 place of formaldehyde, hence there is a crying demand for a more simple, 

 practical and efficient means of rendering the disinfectant available, and 

 the formalin-permanganate method should win a place for itself. 



Some preliminary experiments, carried out to determine the merits o, 

 demerits of this new method as applied to disinfection in a practical wayr 

 verified the results obtained by the department of Public Health and Marine 

 Hospital Service in their experiments to determine the best means of dis- 

 infecting railroad coaches. During the progress of our experiments it was 

 found that, when potassium permanganate crystals were added to formal- 

 dehyde in the above named proportions, in quantities sufficient to disin- 

 fect the ordinary sized living room, very violent ebullition and foaming 

 occurred, causing the material to boil over sides of receptacle. In our 

 trials 240 grams of potassium permanganate crystals were placed in an 



