114 



AGRICULTURE HANDBOOK 184, U.S. DEPT. OF AGRICULTURE 



(9) Fifteen seconds after the boiling stops, add 

 water to the test tube until it is two-thirds 

 filled. 



(10) Observe the color of the solution and 

 compare it with the two colors marked + and - 

 of the color scale furnished with the Clinitest 

 tablets. Disregard everything else on the scale 

 card. The other colors and the" labels on the 

 scale card have no relation to this test. Make 

 the color comparison in a room illuminated with 

 an incandescent bulb. The colors are not easily 

 judged by fluorescent or direct sunlight. 



Intvritretinfi the Krsiills 



Color of Solution in Test lube. — Blue indi- 

 cates a negative test; the sirup contains less 

 than 2 percent of invert sugar and can be used 

 to make cream. Yellow or yellow gi-een indi- 

 cates a positive test; the sirup contains more 

 than 3 percent of invert sugar and is not suita- 

 ble for making cream. 



Quantitative Test 



The quantitative test is much longer than the 

 simple test; it requires about 15 minutes. 



I'rpparing the Siriiit-Wtiter Mixtures 



For this step, you will need sirup, 15 quarts of 

 water, measuring cup, quart measure, pail or 

 other large container, long-handled spoon, 

 small spoon, and five 4-ounce drinking glasses. 

 The glasses should be thoroughly dry. You will 

 also need a pencil and labels. 



Stir thoroughly the sirup to be tested. Then 

 fill the measuring cup exactly to the 1-cup mark 

 with sirup. 



Dilute this sirup with five successive addi- 

 tions of water, as follows: 



l-and-1'2 Dilutimi (1 cup of sirup and 12 cups 

 of water). — Pour 2 measured quarts (8 cups) of 

 water into the pail. Pour the cupful of sirup into 

 the pail; let the cup drain until most of the 

 sirup is out of the cup. 



Measure a third quart (4 cups) of water and 

 use this to rinse the remaining sirup from the 

 cup; fill the cup with water, stir with a small 

 spoon, and pour into the pail until the quart of 

 water is used. 



Stir the sirup and water in the pail until it is 

 thoroughly mixed. 



Dip one 4-ounce glass into the dilute sirup 

 and withdraw half a glassful. 



Label the glass "12" and set it aside. 



l-and-20 Dilution. — To the dilute sirup in the 

 pail, add 2 measured quarts (8 cups) of water. 



Stir tlie contents of the pail until well mixed. 

 Remove half a glassful and label it "20." 



l-and-32 Dilution. — Add 3 measured quarts 

 (12 cups) of water to the mixing pail. Stir 

 contents until well mixed. Remove half a glass- 

 ful and label it "32." 



l-and-40 Dilution. — Add 2 measured quarts (8 

 cups) of water to the pail. Stir contents until 

 well mixed. Remove half a glassful and label it 

 "40." 



l-and-60 Dilution. — Add 5 measured quarts 

 (20 cups) of water to the pail. Stir contents until 

 well mixed. Remove half a glassful and label it 

 "60." 

 Color Tesliiifi the Dihitioiis 



For this step you will need the labeled sam- 

 ples of the five dilutions, test tube holder for 

 five tubes, five test tubes, six medicine drop- 

 pers, Clinitest tablets and color scale, a small 

 amount of water, and pencil and paper. 



Make the color test as follows: 



(1) Place five of the test tubes in the test tube 

 holder. 



(2) Fill a clean, diy medicine dropper with the 

 diluted sirup from the glass labeled "60." Hold 

 this dropper upright above the test tube in the 

 hole marked "60" and let exactly five drops of 

 the diluted sirup fall into the test tube. 



Similarly, place exactly five drops of the "40" 

 dilution, five drops of the "32" dilution, five 

 drops of the "20" dilution, and five drops of the 

 "12" dilution in the tubes numbered for these 

 dilutions (see fig. 123). Use a separate, clean, 

 dry medicine dropper for each dilution. 



(.3) Fill another clean medicine dropper with 

 water and add 10 drops of water to each of the 

 five test tubes, refilling the medicine dropi^er as 

 necessary. 



(4) Remove five Clinitest tablets from the 

 bottle or wrapper. Place them on a clean piece 

 of paper. 



(5) Place one tablet in each test tube, in order, 

 starting with the tube marked "60." 



The tablets, as they dissolve, cause the con- 

 tents of the tubes to boil. Do not move the test 

 tubes while tlie solutions are boiling. 



