r913] KNIGHT & CROCE Teter OF SMOKE 357 
c. washed smoke absorbed with bromine; epicotyls 37 cm. long; 
no seling and little declination. 
7- 550 cc. washed smoke absorbed with bromine; epicotyls 3-5 cm. long; 
saiellivig 2-3 cm.; declination 10°-60°. 
It is evident from this series of cultures that absorption with 
bromine greatly reduces the toxicity of paper smoke and shows 
that substances belonging to the heavy hydrocarbons are the ones 
determining the toxic limit. _The response given with 550 cc. of 
bromine-washed smoke is probably due to the CO, for that amount 
of smoke contains about 82 cc. of CO. 
Experiment V.—The effect of coal smoke 
The smoke was withdrawn from the furnace of a large flat 
building on a cold day, when large volumes of soot-free air were 
pouring from the chimney. The smoke showed the following 
analysis. 
Vohume atisivred sc. ha 93-6 cc. 99.3 Cc. 
Aiiter: NaOH. a oes os Se ered oS esG g2.2 97.6 
Difference=CO,+S0,........:.. 1.4 r.7 
92.2 97.6 
Adter phosphorous: . i455 9-5 75.8 80.2 
Differentes Oy 3 . a ve Ie 17.4 
75.8 80.2 
After ammoniacal cuprous chloride 75.6 79.9 
Difference=CO.........- hie 0.2 0.3 
This smoke contained about 1.6 per cent of CO, and SO, 
together; long storage over water had probably reduced somewhat 
the percentage of these gases. The oxygen was reduced to a little 
less than 18 per cent, while only a trace of CO was present. 
The following data report the results from exposing the test 
seedlings to various concentrations of this smoke. Part of these 
cultures were run in water-sealed bell jars and part of them in cans. 
At the beginning of the experiment the epicotyls were 2-3 cm. long, 
and after every exposure were slim and straight. 
1. Control; epicotyls 6-12 c 
2. 20 cc. in ro-liter chamber; ree 6-13 cm, tall, 
