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20 BULLETIN 1159, U. S. DEPARTMENT OF AGRICULTURE. 
attention to the details of titration and a reading of the hydrometer. 
With a little practice a test can be made in a compartively sho 
time. The apparatus and chemicals required can be purchased from 
any reputable chemical supply house. The entire outfit can be 
packed in an ordinary suitcase and carried from place to place. 
Directions are here given for making the solids-acid tests, com- 
piled from directions furnished by the Bureau of Chemistry of the 
United States Department of Agriculture and by the Florida Agri- 
cultural Experiment Station. . 
APPARATUS REQUIRED. 
A Brix spindle, graduated in tenths of a degree, ranging from 0° to 15°. 
A Fahrenheit or centigrade chemical thermometer. 
A 25 cubie centimeter pipette. 
A 50 cubie centimeter burette graduated in tenths of a cubic centimeter. 
A burette support. 
A glass cylinder, approximately 1; inches in diameter by 12 inches high. 
A small glass funnel. 
Two 500 cubic centimeter Ehrlenmeyer flasks for titrations. 
A lemon squeezer or reamer. 
A granite-ware cup of 1 liter capacity. 
A piece of muslin abeut 18 by 18 inches for straining the juice. 
SOLUTIONS. 
A standard solution of sodium or potassium hydroxid, 1 cubic centimeter 
of which is equivalent to 10 milligrams of citric acid (without water of crys- 
tallization) (factor 0.01), or a normal solution, 1 cubie centimeter of which 
is equivalent to 64 milligrams of citric acid (factor 0.064) or a tenth normal 
, Solution (factor 0.0064). 
A saturated solution of phenolphthalein in 80 per cent alcohol for use as 
indicator (best contained in a 2-ounce dropping bottle). 
DIRECTIONS FOR MAKING THE TEST. 
Sampling.—In order to make the sample as representative as pos- 
sible, not less than 12 oranges are used, preferably taken from sev- 
eral trees. They are halved or quartered, depending upon the size, © 
and the juice removed as thoroughly as possible with a lemon 
squeezer or reamer. Care should be taken to remove the juice from 
all parts of the orange and as thoroughly as possible, for the compo- 
sition is not the same in the center as next the skin. The juice should — 
be well mixed and strained through a muslin cloth. 
Solids.—A glass cylinder is filled three-quarters full with the juice 
and a Brix spindle placed in it. A sufficient quantity of juice is then 
added to overflow the cylinder. The spindle is allowed to remain 
for a few minutes, in order to allow the air in the juice to escape, care 
being taken to see that the spindle does not touch the sides of the - 
cylinder. The reading is then taken, the line just at the top of the 
liquid being the one read. The temperature of the solution is now 
noted, the bulb of the thermometer being placed in the juice and 
gently tapped against the sides of the container until the mercury 
column becomes stationary. The total solids is now found by ref- 
erence to Table 14. 
ACID. Je 
(1) Fill the 25 cubic centimeter pipette by drawing it full of the 
liquid and allow the excess to flow back into the container until the 
upper level of the juice is opposite the zero line. Now, permit the 
contents to flow into one of the titration flasks. Do not hurry the 
flow by blowing into the pipette. 
