4 BULLETIN 158^ U. S. DEPARTMENT OF AGEICULTUEE. 
Ammonia. — Considerable difficulty was experienced in obtaining 
concordant results in the determination of the nitrogen in the form 
of ammonium salts. Boiling weighed amounts of the base goods with 
water and magnesium hydroxide, according to the officiar method/ 
for the determination of ammonia in fertihzers, did not give duplicate 
results sufficiently close for the purpose of this research. Owing to 
the acidity of the sample, it was impractical to use barium carbonate, 
but litharge was used with varying results. Finally, the determina- 
tion was made by using the vacuum distillation method, which gave 
concordant results. This method, which gives only the nitrogen 
found as ammonia or as ammonium salts, is used for the determina- 
tion of amide nitrogen in the products of acid hydrolysis of proteins. 
A weighed quantity of the fertilizer was placed in a Claisen flask con- 
nected up with a cooled receiver of 1 liter capacity and a small guard 
flask of 200 cubic centimeters capacity. Both flasks contained 0.1 N" 
sulphuric acid. To the fertilizer was added 100 c. c. of neutral 95 
per cent alcohol and 100 c. c. of distilled water, together with enough 
10 per cent suspension of calcium hydroxide to make the mixture 
decidedly alkaline in reaction. The ammonia was then distilled 
under a pressure of from 10 to 12 nun., the temperature of the bath 
not exceeding 40° C. In the table which follows are given the results 
obtained by the three methods here used for the determination of 
ammonia. 
Table III. — Nitrogen in the form of ammonia or»ammonium, salts. 
Expressed in 
Method. per cent of 
base goods. 
Expressed in 
per' cent of 
total nitroeen 
in base goods. 
Magnesium hydroxide distillation. 
Lead oxide distillation 
Vacuum distillation 
23. 60 
24.15 
24.47 
23. 09 
23.23 
23.23 
An examination of these results shows that by boiling with mag- 
nesia or litharge, somewhat more nitrogen is found as ammonia than 
really exists in this form in the base goods. It is therefore probable, 
that there are in the base goods nitrogenous compounds which are 
broken down into ammonia by the action of these alkaline reagents 
at a temperature of 100° C. The use of magnesia at boiling tem- 
perature for the purpose of determining the amount of ammonia 
split off by acid hydrolysis from certain proteins which contained 
cystine, was found to give unrehable results.^ The reason for this 
1 Bui. 107, 9 (Revised), Bureau of Chem., U. S. Dept. Agr. 
2 Embden, q':.oted by Giimbel, Hofmeister's Beitrage, 5, 297 (1904): Hart, Zeit. physiol. Chem., 33, 354, 
1901); Folin,ibid., 39, 476 (1903); Denis, J. Biol. Chem., 8, 427 (1910). 
