Mar. 8, 1924 
Hastening the Coloration of Lemons 
761 
large glass or metal vessels with a capacity of from 2,500 to 50,000 cc. 
Allowance being made for the volume occupied by the fruit, gas from the 
stock ethylene-air mixtures was added from a gas burette in sufficient 
quantities (usually 10 to 50 cc.) to give the desired concentration of 
ethylene in the atmosphere surrounding the fruit. This was done 
once or twice daily. The vessels containing the fruit were aerated by 
outdoor air for purposes of ventilation before the gas was added. Control 
lots consisting of fruit receiving treatment with outdoor air only were 
provided in each experiment. The following proportions by volume of 
ethylene to air were tried: 1 to 1,000; 1 to 5,000; 1 to 10,000; 1 to 50,000; 
1 to 100,000; 1 to 200,000; 1 to 250,000; 1 to 500,000; 1 to 1,000,000; 
1 to 2,000,000; and 1 to 5,000,000. 
In all cases coloration of green lemons resulted. The effect was not 
in proportion to the concentration. Concentrations from 1 to 1,000 to 
1 to 200,000 produced approximately the same effects, coloring the lemons 
in from 5 to 8 days. Concentrations down to 1 to 2,000,000 
were somewhat less effective, requiring 1 or 2 days longer. Con¬ 
centrations of 1 to 5,000,000 required about 14 days, indicating that 
this concentration represents the highest dilution at which coloration is 
markedly hastened. 
The effect of ethylene was further checked in one case by bubbling 
the gas-air mixture through bromin water before permitting it to come 
in contact with the fruit. In this case coloration did not result. 
EXPERIMENTS WITH ETHYLENE UNDER COMMERCIAL CONDITIONS 
EFFECTS OF ETHYLENE AND OF STOVE GAS 
Forty-eight boxes of dark-green lemons, divided into two equal lots, 
were placed in two large sweat rooms of commercial size (about 6,600 
cubic feet), provided by a California citrus association. In one room a 
kerosene stove was burned throughout the experiment in a manner 
identical with present commercial practice. Into the other ethylene 
was measured out from the cylinder through a gas meter. Twenty-five 
applications of the gas were made at intervals of six hours, a total of 
48.55 cubic feet being liberated into the room. At first the air was 
stirred with an electric fan to distribute the ethylene, but later this was 
discontinued, being unnecessary. The temperatures and humidities of 
the two rooms were kept the same by close attention and hand regula¬ 
tion, heat equal to that formed by the kerosene stove being provided-for 
the second room by means of hot-water coils near the walls of the room. 
The temperature ranged from 6o° to 65° F., and the humidity from 80 
to 90 per cent. The fruit in both rooms colored in eight days and no dif¬ 
ference in the two lots could be noted, either with respect to the color 
developed or to the commercial quality of the finished product. 
method of measuring and applying the gas 
It was .neither convenient nor accurate to measure the gas from the 
cylinder with a gas meter, but the apparatus shown in figure 2 was 
satisfactory in every respect for this purpose. A is the cylinder of com 
pressed ethylene, and B is an empty cylinder capable of withstandin 
pressures up to 50 pounds. B serves as a “measuring cylinder.” C is a 
pressure gauge, reading in pounds per square inch. It is desirable to 
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