EXAMINATION OF FROZEN EGG PRODUCTS. 91 
hich, fitted with a 2-hole rubber stopper carrying a right-angle air- 
inlet tube, open at the bottom and extending to within } inch of 
the eshte of the cylinder, and a trap containimg either a cotton 
or glass wool plug to prevent any liquid from Tete carried over me- 
chanically. (4) A wide-mouthed 8-ounce bottle fitted with a de- 
livery tube coming from the trap on the aerating cylinder. Jt is 
not essential that the special ammonia absorption tubes be used. 
An ordinary glass tube with a small bulb blown on the end through 
which a few holes are punctured answers very well. The method of 
making these is given by Folin and Farmer.t (5) A means of passing 
air through the system. This is best done by a pump which will 
furnish a blast with a pressure of 10 pounds per square inch and which 
discharges into a tank of sufficient size to compensate for the pulsa- 
tions of the pump and to deliver a steady blast. Suction may be 
used, but itis not recommended. Each of the first four parts enumer- 
ated is fitted with a 2-hole rubber stepper, and all are connected by 
glass tubes of suitable shape and length to permit the proper passage 
of air through the apparatus. The tube leading into the acid wash 
bottle should contain a stop cock for reoulating the air supply. 
Weigh approximately 25 grams of sample m a convenient con- 
tainer. Pour as much as possible of this material into the aeration 
cylinder, and transfer the remainder by means of four 25 ce. portions 
of ammonia-free water, stirring each time with a rubber-tipped glass 
rod to remove any ege adhering to the sides of the weighing vessel. 
Add 75 ec. of alcohol, mix well, let stand for 15 mmutes. Add 
approximately 1 gram of sodium fluorid, 2 ee. of 50 per cent 
potassium carbonate solution, and 1 ce. of kerosene. Connect the 
apparatus, and aerate into the receiving bottle, which should contain 
10 ce. of N/50 sulphuric acid, 2 drops of methyl red indicator (satu- 
rated solution in 95 per cent aleaHOEy and about 75 ce. of ammonia- 
free water. The aeration should be carried on for 4 hours, or as 
long as necessary to remove all of the ammonia, using as rapid a 
current of air as possible. Titrate the excess of acid with N/50 
sodium hydroxid (free from carbon dioxid). Express the results 
obtained as milliorams of ammonia, nitrogen per 100 grams of sample 
- onthe wet basis. If there is insufficient time to complete the determi- 
nation, the sample may be left over mght in the cylinder with the 
alcohol and sodium fluorid added. The potasstum carbonate, of 
course, should not be added until ready to proceed. If the sample 
has a bad odor 1t may be necessary to use more > than 10 ec. of N/50 
sulphuric acid. 
Tt is essential that a blank experiment be run to determine the 
percentage recovery of ammonia, using a known amount of pure. 
1J. Biol. Chem. (1912), 11: 496. 
