1908] CROCKER AND KNIGHT—CARNATIONS 267 
To make sure that the effect produced by ethylene was not due to 
some impurity contained by it, parallel experiments were run with 
ethylene derived by two different methods: (1) by heating concen- 
trated sulfuric acid with absolute alcohol, and (2) by dropping abso- 
lute alcohol upon phosphorous pentoxid heated to 200° C. and later 
raised to 240°C. The ethylene derived from sulfuric acid was 
washed by the ordinary gas burette and pipette, as described by 
HEMPEL (15: 34-95); first in concentrated sulfuric acid (sp. gr. 
1.84) to remove the aldehyde, and later in 33 per cent. potassium 
hydrate to remove the sulfur dioxid. In each case the washing was 
continued until no further absorption occurred. The ethylene 
derived from phosphorous pentoxid was washed similarly, and in addi- 
tion in copper sulfate (sulfuric acid solution described by HEMPEL, 
Pp. 316) for absorption of phosphene, if any should be present. 
Various samples of the ethylene derived in this way were analyzed. 
Bromin and fuming sulfuric acid absorbed 96-98 per cent. The 
unabsorbed portion proved to be air, coming from the generator 
chamber. The gases thus derived were diluted with air to form 
“Mixtures containing 2 per cent. ethylene. The toxicity of the two 
mixtures was equal. 
In discussing the composition of illuminating gas we can hardly 
do better than quote a paragraph from SrrH’s (16) General chem- 
tstry for colleges: 
The illuminating gas in Europe, and in many of the smaller cities of the 
United States, is usually coal gas; while in the larger cities of America it is almost 
always made from water gas. Coal gas is obtained by the destructive distillation 
of soft coal, and is freed from ammonia and tar by washing and cooling, and from 
hydrogen sulfid and carbon dioxid by passage through layers of slaked lime. 
The water gas, made by the action of steam upon anthracite or coke, being com- 
Posed of carbon monoxid and hydrogen, has no illuminating power. It is there- 
- “carburetted,” that is, mixed with hvdrocarbons, by passage through a 
Cylindrical structure filled with white-hot firebrick, upon which falls a small 
Stfeam of high-boiling petroleum. The relatively involatile hydrocarbons of 
Which the oil consists are thus decomposed (“cracked”), and gaseous sub- 
ere ot high illuminating power are produced. The following table shows 
Composition of each of these kinds of gas, together with that of oil 
ing” oe asia which is composed entirely of the products from “crack- 
