Mar. 8, 1924 
Hastening the Coloration of Lemons 
767 
has remained in the room for at least an hour after liberating a charge of 
gas and at no time has he noted any physiological effects. The concen¬ 
trations necessary to produce anesthesia are about 800 to 8,000 times as 
strong as those recommended for coloring lemons. 
COST OF ETHYEENE TREATMENTS 
One cylinder of ethylene holds about 320 cubic feet of the gas at ordi¬ 
nary pressure and temperature. At present prices, the gas costs about 
3/4 cents per cubic foot, exclusive of the transportation charges and the 
value of the cylinder, which can be returned to the manufacturer for 
refilling. The cost of gas for coloring a carload of fruit should not exceed 
a dollar. 
EFFECT OF MISCEEEANEOUS GASES AND VAPORS UPON THE COEORA- 
TION OF GREEN DEMONS 
During the course of the experiments, the effect of many, substances 
upon green lemons was tried. A surprisingly large number caused 
yellowing of the fruit, but in most cases no practical application of the 
fact could be found, either because of injury to the fruit, expense of the 
reagent, its poisonous character, etc., or because the color developed was 
not the bright lemon yellow desired in commercial practice. 
Among the substances that induced coloring but caused injury were 
paracresol, pyridin, ethyl butyrate, methyl amin, bromin, formalde¬ 
hyde, acetaldehyde, chlorin, amyl nitrite, formic acid, nitric acid, and 
benzine. Substances causing coloration in strong concentrations but not 
in low concentrations were acetic acid, hydrochloric acid, trichlorethylene, 
and amyl acetate. Substances producing fairly good color without 
injury were gasoline, phenol, and chloral hydrate. Substances producing 
slight effects or none were calcium hypochlorite, hydroxylamin-hydro- 
chlorid acid, alphanaphthylamin, guaiacol, sulphanilic acid, salicylic 
acid, benzoic acid, trimethylethylene, kerosene, turpentine, asphaltum, 
and ethyl ether. Methyl chlorid from a commercial cylinder at a con¬ 
centration of 1 to 1,000 caused good coloration of lemons in 10 days, 
and that at a concentration of 1 to 100,000 caused slight coloring. In 
this case, however, it can not be stated that the methyl chlorid did not 
contain traces of ethylene. 
SUMMARY 
Some commercially mature lemons are green in color when picked. 
The desired yellow color must be secured by subsequent treatment. 
When forced coloring is desirable, the change from green to yellow 
is hastened by the use of the combustion gases that arise from kerosene 
stoves during the burning of kerosene. The object of the investigation 
here reported was to determine the identity of the gaseous constituent 
responsible for the coloration of the fruit. 
After the mixture of gases from a kerosene stove had bubbled through 
Pettenkofer tubes filled with bromin water, the residual (unabsorbed) 
gas failed to induce coloration. This suggested that the effective con¬ 
stituent must be among the unsaturated hydrocarbons. 
Ethylene, even in low concentration, caused green lemons to turn 
yellow. Fruit colored in this way did not differ in any detectable manner 
