75 « 
Journal of Agricultural Research voi. xxvn, No. 10 
EFFECT OF GASES ON COLORATION OF LEMONS AS DETECTED BY 
STANDARD ANALYTICAL METHODS 
STOVE GAS 
No analyses of the combustion products from kerosene stoves were 
found in the literature. Analysis of samples taken from the air above 
the burning flame showed: Carbon dioxid (C0 2 ), 0.73 per cent, 0.63 per 
cent; oxygen (0 2 ), 20.01 per cent, 19.94 per cent; no unsaturated gases; 
and carbon monoxid (CO), 0.48 per cent, 0.05 per cent. Analysis of 
samples of ordinary air, using the same apparatus and reagents, gave: 
Carbon dioxid (C 0 2 ), 0.0 per cent, 0.04 per cent; oxygen (0 2 ), 21.04 
per cent, 21.11 per cent; no unsaturated gases; and no carbon monoxid 
(CO). The oxygen percentages were, of course, too high, but no attempt 
was made to determine the cause. The data indicated that it was not 
feasible to search for the effective gas by ordinary gas-analytical methods. 
AUTOMOBILE EXHAUST GAS 
Sievers and True (17) pointed out that the exhaust gas from automo¬ 
bile engines can color lemons. The composition of this gas has been 
very carefully determined (<?, 2). Emphasis was laid upon completeness 
of combustion, however, because of its importance from the standpoint 
of fuel economy, and upon the quantity of carbon monoxid formed, 
because of its toxicity to man. The other gases present were not sorted 
out individually but were listed as heavy hydrocarbons, unsaturated 
gases, illuminants (C n H 2n ), etc. 
SWEAT-ROOM ATMOSPHERE 
S. A. Weirman, formerly of the laboratory of fruit and vegetable chemis¬ 
try, United States Department of Agriculture, analyzed many samples 
of air taken from various sweat rooms in which fruit was being colored 
by kerosene stove gas. The quantities of carbon dioxid varied from 
0.1 per cent to about 1.5 per cent, in one case reaching 4.9 per cent. The 
oxygen content was generally about 18.6 per cent. Carbon monoxid 
in small quantities was found in some samples. Less than one-third of 
the samples showed the presence of heavy hydrocarbons, the greatest 
quantity being 0.25 per cent. 
CARBON MONOXID AND CARBON DIOXID 
The two gases among the combustion products positively identified 
by these methods are carbon monoxid and carbo» dioxid. Carbon 
dioxid in a wide range of concentration was tried by Weirman, but it 
failed to produce the desired result. He found also that carbon monoxid 
in high concentration did not induce coloring. Eater experiments, 
however, have shown that weaker concentrations are effective. Eight 
per cent of carbon monoxid caused coloration in about one week, even 
with gas that had been bubbled through bromin water to remove un¬ 
saturated hydrocarbons. However, 1 per cent of carbon monoxid was 
ineffective, only a slight change resulting, and one part of carbon monoxid 
in 1,000 parts of air gave no detectable change. 
Therefore carbon monoxid is not the effective constituent, since concen¬ 
trations of this gas sufficient to produce coloring would cause the death of 
