xvi REFORMS IN CONDITIONS OF SUPPLY 291 



At the end of 24 hours there was no noticeable difference in 

 the acid content as shown by eleven trials conducted under 

 ordinary dairy conditions. The aeration also made no appre- 

 ciable difference to the development of the bacteria. 



In America it appears to be the universal procedure to send 

 milk in un ventilated churns. Thus Eastwood 1 remarks: "All 

 the American cans I saw were covered with a closely-fitting 

 metal lid, none of the lids were perforated " ; and also : " The 

 fact that, in the American trade, milk is hauled in dust- 

 proof receptacles demonstrates the absurdity of the notion that 

 ventilation holes are necessary." In addition to being non- 

 ventilated the churns should be dust-proof and of more 

 hygienic construction. 



The points which must be taken into consideration in 

 devising a churn which will satisfy both sanitary considera- 

 tions and trade requirements are the following : 



(1) Trade requirements are in favour of one size only. 

 The general convenience of one standard size outweighs the 

 fact that a churn may sometimes have to travel half full. 

 Proper cleaning brushes in use at the large factories will only 

 fit the one size. 



(2) The ordinary 17-gallon churn is convenient to the 

 trade. It holds a lot of milk, while it is rollable and can 

 just be lifted on to a cart. This size of churn is easily cleaned 

 by steam. On sanitary grounds, however, it is too large for 

 thorough cleansing when steam is not available. 



(3) The churns are subjected to much rough usage and 

 must be strongly made. It is particularly important that 

 the neck and lid should be very strong, otherwise they get 

 out of shape and the lid will no longer fit properly. 



(4) From the sanitary point of view the structure of the 

 lid is all important. The type with everted lid (Fig. 18, 

 type A, p. 260) is often recommended, but as it will not 

 satisfy the exigencies of the trade it is not a good type. The 

 bent-over lid always, sooner or later, gets knocked out of shape, 

 and the top will not fit properly. Churns of this type cannot 

 stand on top of one another. This the trade finds necessary 

 both to economise space in depots and in the carriage of empties. 



(5) The churn must be lockable, non- ventilated, water 



1 Report to the Local Government Board, 1909, new series, No. 1, p. 76. 



