UNITED STATES DEPARTMENT OF AGRICULTURE 
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BULLETIN No. 565 
Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 
Washington D. C. 
May 11, 1918 
HOW TO CANDLE EGGS. 
By M. E. Pennington, Chief, Food Research Laboratory, M. K. Jenkins, 
Assistant Bacteriologist, and H. M. P. Betts, Artist. 
CONTENTS. 
Page. 
Introduction 1 
Grading of eggs 2 
The egg candle 2 
The structure of the egg 3 
How to hold an egg when candling- 
What to look for in candling an egg- 
Classified description of eggs before 
the candle and out of the shell 
Page. 
12 
INTRODUCTION. 
Ability to candle eggs is becoming more and more important to 
farmers, merchants, and shippers in the country districts. 
Laws in many States impose a penalty for selling bad eggs and 
the Federal Food and Drugs Act prohibits the interstate shipment 
of cases containing substantial percentages of bad eggs, which are 
held to be adulterated food. Only by candling can a shipper make 
certain that his eggs comply with Federal, State, and other regula- 
tions. 
Aside from its value in enabling one to comply with legal require- 
ments, ability to judge the condition of eggs in the shell has a distinct 
monetary application and in many sections is simply a matter of 
economic self-protection for the farmer and the country dealer. The 
custom of buying eggs on a grading basis is spreading rapidly, and 
the collectors in the great market centers are becoming much stricter 
in rejecting inedible eggs, just as consumers are becoming more criti- 
cal and are refusing to pay for doubtful eggs delivered to them by 
the retailer. The producer or country shipper who ships uncandled 
eggs runs the risk, therefore, of losing freight charges and packing 
costs on all inedible eggs, and where such eggs are included may get 
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