THE MILK CONTRACTOR 289 



min. Several holding tanks in series are more trustworthy than one, for 

 the first tank acts as an equalizer and the others hold the milk at the 

 desired temperature. Pasteurizing plants should be under official con- 

 trol for they are too important in preserving the public health to be left 

 to the caprices of the individual. 



5. Advent of the Holder Process. The fifth important factor in 

 establishing faith in pasteurization was the development of the holder 

 process. With the perfection of machinery that made commercially 

 available a process of pasteurization which was endorsed by medical men 

 as effective and as not materially altering the milk, public confidence in 

 pasteurization was largely restored. 



6. Success of Child Welfare Stations. The convincing work of child 

 welfare stations influenced the public favorably toward pasteurization. 

 The pioneer work of Hoplik, the widely advertised work of Straus and 

 of a shoal of others in all parts of the United States who distributed 

 pasteurized milk to the children of the poor with good results, familiarized 

 people with this new product and satisfied them that it was safe. 



7. Finally, it became appreciated that if any large percentage of the 

 entire milk supply of the public was to be pasteurized it must be done 

 outside of the home. , A small amount of milk might be pasteurized for 

 children but it was too much of a tax on the overburdened housewife to 

 expect her to pasteurize the milk of the whole family. Furthermore, it 

 was as desirable that the milk consumed in restaurants and hotels should 

 be pasteurized as that the milk drunk at home should be, and it was 

 unlikely that this would come about except the milk should be sold 

 already pasteurized by the contractor. 



Pasteurizing Machines. The machines that are used for pasteurizing 

 should be simple, durable and easily cleaned. An intricate machine is 

 more liable to accident than is a simple one; therefore it is not as good, 

 for it must be dependable since the efficiency of the pasteurization is inter- 

 fered with by interruptions. The machine ought to be durable because 

 it receives constant wear from daily use which it must be able to bear 

 well or else the money that is spent in repairs and replacements becomes 

 an excessive tax on the business. As heated milk is prone to stick to 

 pasteurizers they must needs have a thorough cleaning daily. This re- 

 quires labor and money ; so to keep the expenditure thereof at a minimum 

 the machine should be easily cleaned. Moreover, a pasteurizer with 

 difficultly accessible parts will not be thoroughly cleaned and so will be 

 likely to contaminate the milk. In type, the pasteurizer should be 

 adapted to the business. A small dairy with a fixed trade needs a differ- 

 ent machine from a large one with a rapidly expanding business. What- 

 ever pasteurizer is chosen it should have a capacity greater than the de- 

 mand that will be made upon it for forcing a machine always results in 

 a poor product. Pasteurizing is done either in vats or by running thin 



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