A method of preserving food substances by keeping them in a low temperature. Freezing machines are used to chill the air for this purpose. This system has come widely into use, cold storage rooms being provided in all our large cities in which vegetables, fruits, and meats can be kept for any desired length of time. They are of much use in markets to preserve the material left unsold. Cold storage meats need to be used soon after being thawed out, as they spoil more quickly than unfrozen meats.