4 BULLETIX 168^ U. S. DEPARTMENT OF AGEICULTUKE. 
less, at least 10 representative ears should be selected for test. In 
all ear-corn samples where it is impracticable to shell completely all 
of the selected ears, an approximately equal portion should be 
shelled from the same point or points on each ear. A simple and 
satisfactory method is to break the ears near the middle and then 
shell from the broken ends. In ear corn the damage can usually be 
very closel}" estimated by classifying a hmited number of eai^, but 
for a more exact determination it Tsill be necessary to shell the 
selected number of ears completely and determine the percentage of 
damaged kernels in the regular manner. 
MIXING SAMPLES FOR DETAILED ANALYSES. 
Care should be taken to see that the samples used for the detailed 
analyses are representative of the larger sample as drawn from the 
car or other bulk. 
A special samphng or mixing machine for this purpose has been 
developed. This mixing machine will be described in detail in a later 
bulletin of the Department of Agriculture. 
SIZE OF SAMPLES. 
The samples taken from the car or other bulk on which the gTading 
is to be based should consist of not less than 1 quart of sheUed 
corn. 
The samples for the more detailed analyses, taken from the larger 
sample representing the bulk, should be as follows : 
Moisture content. — 100 grams for each single test. 
Color. — Not less than 100 grams of screened corn. 
''Cracked'' com and foreign matei'ial, dirt, etc. — At least 200 grams of the carefully 
mixed sample. In using a 200-gram sample it must be remembered that the weight 
in gi'ams of each of the two factors must be divided by 2 to ascertain the percentage. 
Damaged corn. — Preferably, on the whole of ^That remains of the sample after remov- 
ing the cracked corn, the foreign material, dirt, etc. In this connection it 
should be remembered that the percentage of damaged corn should be based not on 
the weight of the screened sample but on the weight of the sample taken for analysis 
before removing the cracked corn, the foreign material, dirt, etc. For example, in a 
200-gram sample showing 3 per cent of cracked corn and 2 per cent of foreign mate- 
rial, dirt, etc., there would remain 190 grams to be analyzed for damaged kernels. 
Damaged kernels weighing 20 grams based on the original 200-gram sample would 
therefore be equivalent to 10 per cent, whereas if incorrectly based on only 190 grams 
the percentage of dirt would show as 10.4 per cent. 
SIEVES FOR SCREENING SAMPLES. 
The sieves for screening the samples should be made of metal 
perforated with round holes. The holes in the upper or first sieve 
should be one-quarter of an inch in cUameter and the holes in the 
lower or second sieve nine sixt^^-fourths of an inch in diameter. 
Figures 1 and 2 show these holes of natural size and the approximate 
