AGRICULTURAL EXPERIMENT STATION. 75 



cooling, be in condition to measure with the pipette. On account 

 of the small particles of curd, sour cream adheres much more to 

 the walls of the pipette than sweet cream, therefore a little w r ater 

 (4 or 5 c.c.) must be used to rinse the pipette into the test bottle. 

 Unless this is done the results will be from 0.2 to 0.4 per cent, too 

 low. About 20c. c. of acid should be used when the pipette is 

 rinsed. When the cream is frothing badty and contains a large 

 amount of air or gas bubbles, as is sometimes the case with cream 

 that is very sour or taken from a separator, it cannot be accur- 

 ately measured but must be weighed. The writer has made several 

 tests when the error in measuring frothy cream was over 5 percent, 

 of the total fat. 



The only accurate method to pursue in such cases is to weigh 

 the cream, and this can be very easily done by any one who has skill 

 enough to make the test. A good little scale for the purpose is 

 made by the Springer Tortion Balance Co., 92 Reade St., N. Y. 

 Their No. 802 Handy Scale, costing about $4.00 with a weight 

 that when put on the 8 oz. notch weighs 18 grams, is sufficiently 

 accurate, and very convenient. We would advise creameries using 

 this test to get a scale for the purpose mentioned, for there will 

 be instances when it will save much time and trouble. The 

 method of using the scale is very simple. The empty test bottle 

 is set on the pan and counterpoised by means of the ounce weight 

 and screw at the end of the scale arm ; then the 18 gram weight is 

 put on the 8 oz. notch, the pipette filled with cream a little above 

 the mark aud emptied into the test bottle until it is nearly all in, 

 when the finger is pressed on the top of the pipette sufficiently to 

 allow the cream only to drop slowly till the scale turns. One can 

 weigh with a little practice about as rapidly as he can measure. 

 This scale will also be very convenient in testing butter and cheese, 

 as with solids it is necessary to weigh out the portions for the test. 



In using the test bottle No. 3 the method is slightly mod- 

 ified in the latter part of the process. The base portion, into 

 which has been measured the cream and acid, is put in the centri- 

 fugal machine and whirled for five minutes the same as with the 

 ordinary bottles. As much hot water is then added as the. base 

 will hold without danger of spilling, and whirled for two or three 

 minutes more, to collect the fat on the top of the water. The base 

 is then taken and connected with the graduated neck by a piece of 

 rubber tubing. The whole is then put in a tank or pail of water, 

 heated to about 110 to 120 F. aud the fat raised into the neck bv 



