Mar. 8,1934 
Hastening the Coloration of Lemons 
763 
place in 10 days. In an incubator at 93 0 F. and with ethylene of a i 
to 10,000 concentration, coloration took place in 9 days, but the color 
was not as well developed as with a similar lot of fruit held at a tempera¬ 
ture of 68° to 72 0 F. Thus a law temperature practically inhibited 
coloration and a high temperature reduced the rate. 
EFFECT OF REDUCING THE NUMBER OF GAS APPLICATIONS 
In the first experiments in commercial rooms, gas applications were 
made four times a day. More than two a day would be inconvenient in 
practical work. Accordingly, about half a carload of green lemons, 
representing boxes of fruit from several groves, were placed in a sweat 
room and one cubic foot of ethylene was released into the room twice 
daily. For the purpose of ventilating the fruit, once daily, just before 
a gas application, the ventilator and doors were opened for one hour, 
and air was drawn into the room by means of an electric fan. The 
temperature of the room during the experiment was 68° to 73 0 F. (aver¬ 
age, 70°). The humidity was 75 to 90 per cent (average, 81 per cent). 
The different lots of fruit in the room colored at different rates. The 
first lot was removed at the end of 4 days, and other lots at the end of 
6, 7, and 8 days. One lot was not completely colored at the end of io 
days. The color and condition of the fruit at the end of the experiment 
were satisfactory. It is not known what concentrations of ethylene 
existed in the room during the experimental period, since no method of 
estimating ethylene in such low concentrations was found. After 
liberation of the gas diffusion losses at once began. The extent of these 
losses could not be determined, but data in an unsigned article ( i) 
regarding air exchange in a closed room indicate that they would be 
large. The experiment, however, showed that two applications of gas 
a day were sufficient to induce coloring. 
COLORING FRUIT IN TENTS 
Fruit was not placed in a special room, but the boxes were stacked in 
am open hallway and covered with two thicknesses of ordinary cotton 
tent canvas, such as is used in fumigating with hydrocyanic acid gas. 
Four times daily the outlet hose from the cylinder was pushed under the 
edge of the tent and ethylene was admitted to make a concentration df 
ethylene amounting to i part in 250. This lot was exposed to the 
temperature of The outdoor air and varied from 50° to 76° F., with an 
average of 58°. ' 
At the end of 10 days the fruit was full yellow. The color was slightly 
paler and more attractive than that of similar fruit colored in regular 
sweat rooms. It appeared that the tent covering retained the gas well 
enough to permit coloring to proceed in a satisfactory manner. 
CONDITIONS PREVENTING OR RETARDING RATE OF COLORING 
HIGH CONCENTRATIONS OF ETHYLENE 
Large bottles were filled with a gas mixture consisting of 80 per cent 
ethylene and 20 per cent oxygen by volume. By water displacement, a 
supply of gas was pushed over once each day into desiccators containing 
green lemons. For comparison, a second lot of fruit was treated in a 
similar way, except that the ethylene concentration was 1 to 1,000. A 
third lot received no gaseous treatment but was aerated with outdoor 
air each day. At the end of 7 days, the lemons in the third (control) 
