362 APPLIED BACTERIOLOGY 



and left exposed to the disinfectant atmosphere for many 

 hours. The latest investigations (Abba and Rondelli, 

 Rivista d'Igiene, July and August, 1897, and Piton, 

 Archives de Medecine Navale, Ixvii., 6), confirm the 

 balance of experience up to date, and demonstrate that the 

 use of formaldehyde vapour, even pushed to a strength 

 considerably beyond what is usual, leaves organisms liable 

 to escape disinfection, the feeble penetration of the gas 

 being responsible for the failure. 



Equifex Spray Disinfection. — On the whole, the most 

 convenient and trustworthy method of disinfecting what 

 cannot be exposed to steam lies in the use of the Equifex 

 sprayer with a disinfectant solution. This instrument 

 consists essentially of a strong reservoir, in which the dis- 

 infectant solution is either placed beforehand or pumped 

 during the operation. Air is compressed by means of a 

 pump, and part of it drives the solution through a flexible 

 tube to a spraying-nozzle, in which, by a suitable con- 

 trivance, the velocity of the stream of liquid is cut down, 

 while part passes under pressure through a parallel tube 

 and catches up the stream of disinfectant, which it carries 

 through the actual spray-producing nozzle. The relative 

 proportions of air and disinfectant can be regulated at will 

 by means of cocks ; and thus a spray is projected on to the 

 surface to be treated at a velocity suflficiently high to 

 ensure penetration, and of a fineness which it is found in 

 practice can be so adjusted as to leave the surface even of 

 common wall-paper uninjured. This method is now coming 

 mto more general use in this country; in France it has 

 been generally adopted for some years with good results. 

 The practice is to spray vertically upwards, as it were in 

 vertical stripes ; and when a room is finished it is gone over 

 a second time, the chance of the same spot being missed 

 twice being thus reduced to a quantity which may be 



