THE MILK CONTRACTOR 331 



for any sized plant, no equipment is required and the overhead expense 

 is not considered. It appears that the line representing brush washing 

 is uniformly below that for hand washing while the automatic machine 

 is shown to be cheaper than the latter when 1,200 to 1,300 bottles are 

 washed. The lines representing the automatic and the brush- washing 

 machines intersect at 2,300 bottles indicating that with this number of 

 bottles to wash a dealer would do well to install an automatic machine. 

 The Division points out that comparatively few plants were covered and 

 that the amount of power required has not been included in calculating 

 these costs. 



Storage and Inspection of Bottles. In small dairies the washed bot- 

 tles are kept in the milk-handling room. In the larger dairies the bottles 

 are carried on roller conveyors to the storage room. On the way the cases 

 are carefully inspected for chipped and cracked bottles and a sharp watch 

 is kept for such bottles while the empty bottles are being fed into the 

 filling machine. 



Sterilization of Bottles by Steam. After bottles are washed they 

 should be sterilized. In plants large enough to afford a stationary boiler 

 the sterilization is done either in streaming steam or steam under pressure, 

 usually 15 Ib. for 15 min. being used. When the steaming is done con- 

 scientiously it is efficacious but if done in a haphazard way the bottles 

 may be merely warmed up to the incubating temperature and conditions 

 created for bacterial multiplication. 



Sterilization of Utensils, Etc., with Washing Powders. The great 

 majority of dairymen cannot afford steam. So it would be advantageous 

 if a cheap safe disinfectant were available for their use. Doane defined 

 a good creamery disinfectant as one that is odorless, tasteless, non- 

 poisonous, cheap and in small quantities is reasonably effective, and that 

 is germicidal to non-spore-bearing forms. " He quotes the work of others 

 on the value of soaps as disinfectants and tested the disinfecting power 

 of several washing powders. 



Experiments with one or two soaps indicated that in 5 per cent, solu- 

 tion they are effective germicides. To the free alkali, the disinfecting 

 power of the soap is partly attributable but he is inclined to believe that 

 either the glycerin or salts of the fatty acids of the soap have bactericidal 

 properties. Since the appearance of this paper, the disinfecting power 

 of soaps has been questioned; Pease has recently stated that it is con- 

 siderable when the water is hot. 



While the composition of the washing powders with which Doane ex- 

 perimented is a trade secret analysis showed that they were 80 per cent, 

 soap and 20 per cent, free alkali the latter being caustic soda. In ex- 

 perimenting, his procedure was to make a dilution 0.1 to 0.5 c.c. of milk 

 in 5 c.c. of sterilized water. Then for the controls a measured quantity 

 of the dilution was put in another 5 c.c. of sterilized water and measured 



