306 CITY MILK SUPPLY 



an aggregate that is serious, that it is impossible to even imagine the proper con- 

 duct of such plants without supervision of an inspectorial nature." 



Sterilization of Milk by Electricity. The question is often asked 

 whether it is possible to sterilize milk by electricity. The process of the 

 Goucher Electric Purifying Co. does so. The milk is filtered through 

 cheese cloth and absorbent cotton into a large tank where it is kept in 

 constant motion to prevent the cream rising. From the tank it is pumped 

 through pipes to an electrical purifying apparatus, being subjected on the 

 way to a steam temperature which can be regulated to any desired degree. 

 In the electrical purifying machine the milk is exposed to an alternating 

 current of 1,920 to 1,960 voltage and 7.5 to 8.5 amperage. The current 

 is obtained through a 1 to 10 transformer. By exposure to the current 

 the milk is raised in temperature, consequently the temperature of the 

 milk on issuing from the electrical machine is the temperature it had on 

 entering it plus the temperature acquired in the machine, which means 

 that the final temperature is in measure determined by the degree of 

 steam heating it receives. As the process is often operated, the milk is 

 heated to about 150F. by steam and is raised to 164F. by the electrical 

 apparatus. From the electrical machine the milk runs over coolers to a 

 bottling tank. The passage of the milk from the receiving tank through 

 the steam-heated pipes and electrical machine to the bottling tank is said 

 to take less than a minute so that the process partakes of the nature of 

 flash sterilization. The proprietors put out literature giving the findings 

 of several commercial laboratories that the process effects a good bacter- 

 ial reduction, destroys disease germs, does not alter the chemical consti- 

 tution of the milk and tends to increase rather than to decrease the volume 

 of the cream layer. No data is available as to the cost of purifying milk 

 by this process. 



Lewis in England reports tests with an apparatus for pasteurizing 

 milk by electricity. 



"The current which varies in amount with the size of the apparatus but 

 which normally is between 2,000 and 3,000 volts is applied to the milk by three 

 copper electrodes, each of which is enclosed in an electrode chamber. The cham- 

 bers communicate with each other by means of stout glass tubing of even bore. 

 The electrode chambers and the intermediate portions of glass tubing are con- 

 nected by socket joints of India rubber; the whole being built in sections and fast- 

 ened in this way to facilitate cleaning and to make the apparatus somewhat 

 flexible, the bore of the glass or " lethal tube" is relative to the milk output per 

 hour of the particular installation, and the size of the electrode chamber and its 

 enclosed electrode is such as to interfere as little as possible with the flow of milk 

 through the apparatus, and in addition to allow the copper electrode to command 

 the whole bore fully, so that no milk can escape through the apparatus without 

 being submitted to the full action of the current. The electrode is of copper 

 % in. thick and is connected with an electric cable by a flat plate which by a 

 spring contact is forced against a similar flat plate directly connected to the elec- 



