Freedng DONALD COCHRANE Ocean Falls, British Columbia
1F
THERE is a crust of ice on the water pail, you can turn it up and show on the under side of it how the ice grows in spikes, always a t an angle of 60 degrees t o something. This will help the children to understand what happens when apples and potatoes freeze. The ice crystals pierce the cell walls, so that the food spoils rapidly when melted. With apples, freezing produces practically the same results as cooking-warm them in the oven and you haveexcellent baked apples. But potatoes, being starchy, contain an enzyme ta change the starch into sugar, and when the cell walls are punctured it starts to work, with wellknown results. If you have some frozen potatoes, you might try t o extract the sugar by soaking them in water and then boiling the water down. It will probably taste bad, on account of other substances also released by the cold. I read recently that if the potatoes are warmed slowly enough, the sugar will turn back t o starch, but I have not tried it yet. Frozen ears, or fingers, are something diEerent. The cell walls, being made of protein (skim), are not so easily broken as the cellulose (wood) walls of vegetable cells. The danger here is not
from freezing, but from thawing. I t works like this: Living tissue must have oxygen brought to it by the blood That is why you loosen a tourniquet every few minutes. Frozen tissue is practically not living, so it gets along without oxygen. But when i t melts, it must have oxygen quickly, or die. But the arteries are far inside, close to the bone. So if you thaw the frozen tissue from the outside, it is likely to die before the arteries underneath can supply i t with blood. I t must thaw from inside. by the natural heat of the blood. So you masage i t with snow, to stimulate the circulation inside without melting the outside. For the same reason, you should try not to rub the skin, but to rub the flesh backand forth on the bone. I do not recommend any experiments on this section, and I am afraid that none of the above information is of any use for passing examinations. I t is an application of pure science, and is not related to any of the military organizatian--Gen. Science, Maj. Objectives, Pte. Study, or even Cpl. Punishment. -Reprinted
from The B. C. Tenchar.
