4 BULLETIN 168, U. S. DEPARTMENT OE AGRICULTURE, 



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 closely estimated by classifying a limited number of ears, but 

 for a more exact determination it will 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 sampling 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 grading 

 is to be based should consist of not less than 1 quart of shelled 

 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" corn and foreign material, 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 grams of each of the two factors must be divided by 2 to ascertain the percentage. 



Damaged corn. — Preferably, on the whole of what 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 SCREENLNG 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 diameter and the holes in the 

 lower or second sieve nine sixt3'-fourths of an inch in diameter. 

 Figures 1 and 2 show these holes of natural size and the approximate 



