760 
Journal of Agricultural Research voi. xxvn, no. 10 
they were placed in straight glass tubes, 4 to 5 feet long and 3/4 to 1 
inch in diameter. If necessary, gas-washing bottles were inserted at 
WB> the first filled with the proper liquid to remove any vapors carried 
over the absorption tubes and the second to keep the gas saturated with 
water vapor. The residual gas then passed into the desiccators contain¬ 
ing green lemons. In order to permit a conclusion as to the effect of 
the absorbing substances, two control lots were provided. One was a 
similar lot of fruit treated with a stream of unabsorbed stove gas, and 
the other was a desiccator of green fruit aerated each day with outdoor 
air, receiving no gaseous treatment. 
The following solid reagents did not remove the effective constituents 
from the stove gas: Granular calcium chlorid, soda lime, activated char¬ 
coal, and silica gel. Complete removal, however, was obtained by 
means of hopcalite (9, p. no). Stove gas dried by calcium chlorid and 
passed through a small tube containing about 25 gm. of granular 
hopcalite was no longer capable of inducing coloration of green lemons. 
This reagent is noted for its ability to oxidize carbon monoxid, but the 
firm manufacturing it states that not only carbon monoxid but many 
other oxidizable gases are acted upon by it. 
The following liquid-absorbing reagents did not completely remove 
the effective constituent from stove gas: Water, concentrated sulphuric 
acid, 50 per cent potassium hydroxid, 0.75 per cent, potassium per¬ 
manganate, 10 per cent silver nitrate, and saturated aqueous solution of 
mercuric acetate. 
When the stove gas was bubbled through saturated bromin water and 
when the bromin vapor was removed by dilute sodium hydroxid, how- 
over, the residual gas did not color green lemons. This result suggested 
the desirability of testing the effect of unsaturated gases such as ethylene. 
PRELIMINARY LABORATORY EXPERIMENTS WITH ETHYLENE IN 
LOW CONCENTRATIONS 
In the preliminary experiments ethylene was generated by dropping 
ethyl alcohol upon phosphoric acid as described by Doubt (6). When 
it was found that ethylene could be bought as a compressed gas in steel 
cylinders, most of the experiments were conducted with gas from this 
source. An analysis of gas from the cylinder showed that 97.7 per cent 
by volume was absorbed by bromin water. 
For testing the effect upon green fruit of ethylene at low concentra¬ 
tions, gas from the cylinder was diluted with air to make ethylene-air 
mixtures of 5 per cent, 1 per cent, o. 1 per cent, 0.05 per cent, and 0.01 
per cent. Green fruits, the number varying from 6 to 24, were placed in 
