EXAMINATION OF FROZEN EGG PRODUCTS. 89 



water may be added, if necessary, to obtain an even distribution. 

 Dry in the air on a level surface. Make three such slides from each 

 subs ample.- 



Immerse the slides carrying the dried egg films in xylol or benzol 

 for 1 minute. Again dry, and place in 1 per cent carbolic methylene 

 blue for from 10 to 20 minutes. The object is to stain the bacteria 

 deeply, and to stain fat, debris, and background as lightly as possible. 

 To do this, wash off the excess of stain in water, and immerse in 50 to 

 60 per cent alcohol until only a faint blue is visible. This decolorizing 

 is quickly done. Failure to decolorize is followed by serious errors 

 in results. 



Dry, and examine with the microscope, counting 20 fields along the 

 diagonals of each slide. 



A desirable optical combination to employ is that which is used in 

 the direct microscopic examination of milk. The microscope should 

 have an oil immersion objective and an ocular giving the field desired, 

 and should be fitted with a mechanical stage. To standardize the 

 microscope, place upon the stage a stage micrometer, and on the dia- 

 phragm of the ocular place an eyepiece micrometer, with a circular 

 ruling, 8 mm. in diameter, and divided into quadrants. Adjust the 

 draw tube until the inner circle of the eyepiece micrometer has a diam- 

 eter of 0.146 mm. Record the necessary adjustment of the draw 

 tube. By this adjustment, the inner circle will cover 1/7,200,000 cc. 

 of the undiluted egg, giving a factor of 7,200,000. This means that 

 the number of bacteria in a single field should be multiplied by 

 7,200,000, or, if 60 fields are counted, the total number should be 

 multiplied by 120,000, to obtain the number of bacteria in 1 cc. of the 

 original egg material. If any variation from this procedure is used, 

 the factor must be calculated. 



Chemical Examination. 1 



Start the chemical examination immediately after the taking of 

 subsamples, and make all determinations in duplicate. Thaw the 

 subsamples by partially immersing the containers in warm water, the 

 temperature of which should not be above 50° C. Then thoroughly 

 mix them, preferably with an electric stirrer. In the absence of such 

 an instrument in the laboratory, the mixing may be quite satisfactorily 

 accomplished by sucking the melted subsample several times through 

 a Gooch crucible containing no asbestos, using very moderate suction. 

 Examine this mixed composite sample by the following methods: 



TOTAL SOLIDS. 



Weigh approximately 5 grams of the sample into a tared lead- dish 

 of 2| to 3 inches diameter, and dry in a vacuum of not less than 25 

 inches at 55° C, until there is no further loss in weight. This drying 



1 The analytical methods described were very largely devised or adapted to egg analysis by N. Hendrick 

 son, formerly of the Food Research Laboratory. 



