Vor.. LXXIII, No. 4255. NEW YORK, MAY 10. 1!>14. WEEKLY $1.00 PER YEAR. 
CARBON DIOXIDE IN INCUBATION. 
Bad Air in the Incubator. 
I Bn Hot in 70 of the Connecticut Experiment Station 
contains a report of very long and patient work by 
Prof <4. 11. Ramson, Jr., in studying the presence of 
carbonic acid gas formed in incubators. There has been 
much discussion concerning the functions and the ef¬ 
fect of this gas, and we may say that Prof. Ramson’s 
work has solved the problem. The bulletin is a techni¬ 
cal discussion of a chemical question, but Prof. Ramson 
has prepared for us a more practical statement—which 
follows.] 
1IEN YS. INCUBATOR.—The problem of artificial 
incubation has been the question of how we can 
hatch as many and as strong chickens in the in¬ 
cubator as under the hen. Some hold that the same 
per cent, and as strong chickens can be hatched in 
the incubator as under the hen. but this is not sub- 
ing to the suggestion of the incubator manufacturers 
no harm will be done, at least, and the operator 
will approximate the hen’s “out to lunch” periods. 
If these conditions are essentially the same as those 
found under the hen the factor making the differ¬ 
ence between natural and artificial incubation must 
then be elsewhere. The next question comes: Is it 
in the moisture of the air or the chemical composi¬ 
tion of the air? 
MOISTURE.—Just what amount of moisture is 
necessary for the most successful incubation the 
writer does not profess to know. In most of the 
work on moisture the ordinary incubator hygrome¬ 
ters have been used to measure this factor, and these 
instruments are a delusion and snare as far as an 
accurate measurement of the humidity is concerned. 
cessary to construct an apparatus that would have a 
ventilation that was entirely free from any fumes 
of the incubator lamp and at the same time have 
the temperature and moisture controlled. This ne¬ 
cessitated various attachments which would not be 
practical in ordinary incubation or in the commer¬ 
cial incubator, for the aim was not to design a new 
incubator for the market, but to study these factors 
accurately and keep them under control. These in¬ 
cubators were sealed during the progress of incuba¬ 
tion, except for a few minutes to test and weigh 
the eggs. The eggs were turned by a curved device 
on a circular tray, and the air was pumped into 
the incubator at the same rate during each hour 
through the process of incubation, and the air sur¬ 
rounding the eggs was tested by a chemist. Mr. 11. 
stantiated by those who have carefully experimented 
with artificial and natural incubation, and even the 
incubator manufacturers claim that their machines 
only approximate the old hen’s ability to bring off 
good hatches and produce vigorous chicks. What 
the differences are between natural and artificial 
incubation and what the factor or factors that pro¬ 
duce the different results are problems well worthy 
of considerable study, for great is the economic im¬ 
portance to the country if even a small increase can 
lie made in the hatching efficiency of the incubator. 
THE WOODEN HEN.—A temperature of 102% 
degrees Fhr. during the first half of the period of 
incubation and 103% degrees Fhr. during the last 
half of that period closely approximates the tem¬ 
perature found under the average hen. So with a 
level incubator, a reliable thermometer and a rea¬ 
sonable amount of care in looking after the lamp 
and thermostat, the temperature need not worry the 
incubator operator. By turning the eggs twice each 
day this function of the hen is taken care of as 
well as is necessary. If cooling is practiced accord- 
There are as strong adherents of the moisture as 
non-moisture, and while some have had better re¬ 
sults with one than with the other it is known that 
the chick embryo is able to withstand a wide varia¬ 
tion of moisture and hatch. That there is an op¬ 
portunity to get more light on the subject of moist¬ 
ure in incubation by the use of accurate methods is 
evident to anyone who has given this problem much 
thought. 
“BAD AIR.”—It is known that there is in fresh 
air a small amount (.03 per cent.) of a combination 
of gases called carbon dioxide or carbonic acid gas. 
and that this is breathed out by animals, the hen 
included, in large amounts from the lungs. It was 
believed by some that carbon dioxide was the factor 
that made the difference between the hen and the 
wooden hen. for the incubator could not breathe, 
but the fumes from the lamp were known to contain 
carbon dioxide and the question others raised was 
as to the possibility of there being more carbon 
dioxide in the incubator than in under the hen. To 
determine the truth about this question it was ne- 
I). Edmond, by whose ingenuity the construction of 
the apparatus was made a success. The work was 
carried on through the hatching season of five years 
and nearly 10.0(H) eggs were incubated. 
AIR UNDER THE HEN.—The results showed 
early in the experiments that the chief source of 
the carbon dioxide was the chick embryo. With a 
hen sitting on boiled or china eggs the carbon diox¬ 
ide under her was found to lie small in amount. 
With fertile eggs in an incubator or under a hen the 
carbon dioxide increased slowly at first, and rapidly 
after the ninth day of incubation until it reached 
the maximum a little before the chickens hatched. 
This increase closely approximates the increase in 
the weight of the chick embryo. If the ventilation 
was slow and sluggish then the carbon dioxide in¬ 
creased more rapidly and reached a high figure com¬ 
pared with the incubator supplied with a rapid cir¬ 
culation from one quarter of a cubic foot to 15 cubic 
feet each hour during incubation, in other words by 
cutting down the amount of fresh air we allowed 
the carbon dioxide given off from the eggs to ac- 
