290 
Journal of Agricultural Research 
Vol. XXXI, No. 3 
Tiemann nitric oxide gas method. (For literature on this and other 
methods used by Jodidi et al. see literature references (12, 13, 23).) 
According to Jodidi’s procedure, 12 gm. each of healthy and blighted 
celery were repeatedly extracted and thoroughly washed with 85 per 
cent alcohol. Milk of lime was then added to the combined extracts 
and washings, which were then evaporated to dryness in a vacuum 
oven at low temperature. The residue was taken up with hot water, 
lead acetate solution added, and the whole filtered, washed, and the 
combined filtrate and washings made up to 2 liters. In the Scales’ 
method 250 c. c. samples of the extract were placed in 500 c. c. 
Kjeldahl flasks containing 80 gm. of the Zn-Cu couple coils. Five 
grams of c. p. sodium chloride and 1 gm. of c. p. magnesium oxide 
were added and the ammonia from the nitrates thus reduced distilled 
into 50 c. c. of 4 per cent boric acid. In the gas method 250 c. c. 
aliquot portions of the same extract were used and the work carried 
out exactly as described (1, p. 312-315). 
Distillation with magnesia not giving dependable results in the 
estimation of ammonia nitrogen, a modification of Grafe’s method of 
distillation in vacuo at low temperature was employed. Ten-gram 
samples were placed in l-liter flasks, treated with 25 c. c. of con¬ 
centrated sodium chloride solution, 35 c. c. of water, and 15 c. c. of 
alcohol. Then the apparatus was carefully made tight, 15 c. c. of 
saturated sodium carbonate added by means of the separatory 
funnel, and the water pump turned on. The temperature of the 
water bath was then raised to 25° to 29 Q C., at which temperature 
it was held for 3 hours and then raised to 40° to 43° C. The water 
pump reduced the pressure to 21 to 52 mm, mercury, the average 
being 28 mm.; 50 c. c. portion of a 4 per cent boric acid solution 
were used in the Peligot tubes to receive the ammonia. The Peligot 
tubes were placed in the same ice bath and attached bv a Y to the 
same water pump. Near the end of the 6 to 7 hour distillation period 
15 c. c. more of alcohol were cautiously added through the separa¬ 
tory funnels. The distillation was continued 20 to 30 minutes 
longer, during which time the particles of ammonia-containing 
moisture that collected in the necks of the flasks and the conducting 
tubes were removed by squirting a stream of boiling hot water 
against the exterior of the glass. The contents of the Peligot tubes 
were transferred to Erlenmeyers and titrated against standard sul¬ 
phuric acid, using brom-phenol blue as an indicator. 
Only qualitative tests were made for the nitrogen of nitrites. 
Portions of the extract used in the nitric nitrogen determination 
were made neutral and to them were added 1 c. c. quantities of 
sulphanilic acid mixture (15). A red color in the extract from the 
diseased leaves indicated the presence of nitrites. A faint pink 
appeared in the extract from the healthy material indicating a trace 
of nitrite nitrogen. 
Total hydrolyzable nitrogen and nitrogen distribution in the hy¬ 
drolyzed portions were determined as follows: Eight-gram samples 
with 400 c. c. of 20 per cent hydrochloric acid were boiled for 9 hours 
under a reflux condenser. The contents of the flasks were then fil¬ 
tered and washed with ammonia-free water until free from chlorine. 
The filtrate and washings of each 8 gm. sample were thereupon made 
to 2 liters. Total nitrogen was determined on 500 c. c. aliquots by 
the Kjeldahl-Gunning method. Other 500 c. c. portions were evap- 
