TRANSPORT AND STORAGE OF FOOD 435 
fewer than thirty-two gas stores in this country, with a total capacity of 
7,000 tons, and the rate at which they are being erected is rapidly increasing. 
Further, while buyers were naturally sceptical of gas-stored fruit on its 
first appearance, it now commands a definite preference over ordinary 
cold-stored fruit. 
The question ‘ Is the process expensive ?’ is often asked. The answer 
‘No,’ for it so happens that these conditions of 10 per cent. of oxygen 
and 10 per cent. of carbon dioxide are easily obtained in practice. Ordinary 
air contains 21 per cent. of oxygen, and apples will, if enclosed in a gas- 
tight store, soon use up half the oxygen, i.e. ro per cent., and in doing so 
produce the 10 per cent. of carbon dioxide required. When that stage is 
reached, all that is necessary is to maintain it, which is effected by admitting 
fresh air in regulated quantities through simple ventilation. 
But as different varieties of apples differ in their tolerance of temperature, 
so they differ in their tolerance of abnormal atmospheres, and it is necessary 
to determine the proper atmosphere for each variety by carefully controlled 
trials. This is naturally a slow undertaking, but twelve varieties, including 
English Cox’s Orange Pippin, have now been covered. Soon it should be 
possible to obtain this latter variety, which I think is the finest apple in the 
world, at any time of the year. 
Inhibiting Effect of Vapour.—One other point. I was careful to remark 
that the principal products of respiration of the apple were carbon dioxide 
and water. ‘There are, however, other emanations, some of which are in 
minute quantities and have remarkable properties. For instance, if an 
attempt is made to sprout potatoes in air which has passed over apples, the 
growth is inhibited; peas and other seedlings are affected in the same way. 
On the other hand, the emanation actually accelerates the ripening of 
bananas and tomatoes. Whether the phenomenon will prove to be of great 
biological interest we do not know, but it has a commercial interest. The 
emanation from a ripe apple tends to hasten the ripening of young apples, 
and results in a colony of apples, as has long been known, ripening at about 
the same time. 
Large-scale Experiments.—This lecture is necessarily incomplete. It is, 
indeed, little more than a ‘ motorist’s glimpse’ of a large town as he 
bustles through it. 
The experiments I have mentioned may have been pictured by you as 
small-scale experiments in a laboratory, and, indeed, the majority have been 
of that type. But control of temperature, carbon dioxide, and humidity, 
easy though they may be in a laboratory, are much more difficult in a great 
store, such as the hold of a ship. For a cargo of fruit generates heat, gives 
off moisture, and consumes oxygen and produces carbon dioxide. The heat, 
moisture and gas produced by the cargo must be removed, the gas by 
ventilation, and the heat and moisture by the refrigerating plant ; the im- 
portance of the scale of operation is obvious when we remember that the 
larger the cargo, the smaller, relatively, is the surface. Moreover, we are 
dealing with a case where a difference in temperature of half a degree, one 
per cent. more or less of carbon dioxide in the atmosphere, and a difference 
of humidity represented by a mere cupful of water, may turn success to 
failure. 
Special attention is given to these scale effects and other problems con- 
nected with the transport of fruit at sea in an experimental ship’s hold at 
the Ditton Laboratory in Kent. This experimental hold, the only thing of 
its kind in existence, has a capacity of 120 tons. Such a hold is an ex- 
pensive piece of apparatus, but the results obtained are of great value, and 
I venture to think it has already more than paid for itself. 
