THE TESTING OF STEAM DISINFECTORS 3/1 



practically a redetermination of the thermal death-point of 

 the organisms which may be considered to have a resistance 

 equal to that of any which is likely to be treated by the 

 disinfector in practice. It is therefore more satisfactory to 

 take the temperature and exposure required as determined 

 by the data to be found by the collation of the previous 

 experiments, the effect of which has been stated above, 

 and to determine the extent to which the disinfector 

 provides the conditions which have been described as 

 necessary for giving such an exposure to saturated steam 

 free from air. 



To obtain these data it is simplest to use electric and 

 maximum thermometers, a pair being hung up inside the 

 chamber, while another pair are under four folds of 

 blanket, and a third pair are under eight folds. 



The maximum thermometers should be of the Phillips 

 type, in which a small portion of the column is separated 

 from the remainder by a bubble of air. 



They should be capable of registering up to 130° C, and 

 must be tested against a standard thermometer in boiling 

 water every day they are used. 



The electric thermometers should be made with thin 

 bulbs, but the quantity of mercury does not matter much. 

 The bulb must not touch any portion of the wooden frame 

 of the thermometer or the blankets ; if it does erratic 

 results will be obtained. 



The platinum wires must be sealed in, or water will 

 condense in the tube ; it would be convenient if the tube 

 could be left open so as to be able to set the wire so as to 

 make contact at different temperatures, but this cannot be 

 done conveniently on account of the water condensing in 

 the tube. The platinum wire should be as thin as possible, 

 or mercury will stick between it and the sides of the tube. 

 The wires leading from the thermometers to the battery 



24-2 



