The Water Supply and, Drainage of Butter Factories. ' 723 



the same rate as tlie filtering is going on, so that the head of water 

 is always maintained the same. The storage tank should not be any 

 larger than is necessary, as filtered and sterilised water when stored 

 rapidly deteriorate owing to the multiplication of organisms in them 

 which at once begins. This is very marked in the case of sterilised 

 water-. The only attention requii-ed is to clean ofi: the greenish scum 

 which forms on top whenever the rate of filtration becomes too slow, 

 and to remove all the sand, wash it and replace it again about once a 

 year. The scum makes the rate of filtration slower, but it is an 

 advantage so far as the efficiency of the filter is concerned. After the 

 filter has been re-started the water should not be used for the first 

 48 hours, but allowed to run to waste, as it takes some time for the 

 filtration to attain its full degree of efiiciency. 



One of these filters has been in use at the Gormandale factory for 

 the past four years. The sand is simply put into a 400-gallon tank. 

 The water is from a branch of Merriman's Creek, which flows through 

 the swamp. Live stock have free access to it, and from the amount 

 of vegetation in it there was much difficulty in treating it eifectively. 

 The number of organisms before filtration, but after sedimentation, 

 varies from 750 to 3,000. The number in the filtered water is usually 

 below 50. In order to test its efficiency, the sand has never been 

 completely removed, but the upper 12 inches has been changed once 

 since it was started. The scum is removed every six months. The 

 water at present contains 116 per cubic centimeter, so that very fair 

 water is supplied with a minimum of attention and supervision. Mr. 

 Huffer tells me that he has had no complaints whatever about the 

 quality of the butter since the filter was constructed. A filter 10 feet 

 square will be large enough to supply the largest factory. In most 

 localities these filters can be constructed very cheaply, they are nearly 

 self-acting from one year's end to the other, and they can be relied 

 upon more implicitly than any other method. Water containing only 

 20 to 50 organisms per cubic centimeter is as pure as it is practicable 

 to obtain it for manufacturing purposes, and when purification is 

 necessary this method should be carefully considered before deciding 

 the question. 



An Efficient Drainage System. 



Disposal of the drainage of a factory becomes a somewhat difficult 

 problem on account of the amount of organic matter the water con- 

 tains. Decomposition therefore readily takes place, and the drains 

 become offensive, especially in hot weather. The organic matter 

 consists of a little buttermilk and fat ; the amount is apparently 

 trifling in itself but it becomes a nuisance when allowed to deposit 

 day after day in the same spot. The best system of disposal is that 

 adopted at Cowwarr and Boisdale. The water is simply pumped on a 

 small area of ploughed land, and the spot where the water is applied 

 is changed from day to day. The details of this plan are as follows : — 

 All the drains from the factory are led into a sink (say 2 ft. 6 in. by 

 2 ft. 6 in. by 2 ft. deep). From this a 1| in. pipe conveys the water 



