The Chemistry of Cookery

vinegar, and in weak solutions of potash or soda. If the alkaline solution is neutralised by an acid, the gluten is precipitated. If crude gluten, obtained as above, is subjected to the action of hot alcohol, it is separated into two distinct substances, one soluble and the other insoluble. As the solution cools, a further separation takes place of a substance soluble in hot alcohol but not in cold, and another soluble in either hot or cold alcohol. The first, viz. that insoluble in either hot or cold alcohol, has been named _gluten-fibrin_; that soluble in hot alcohol, but not in cold, _gluten-casein_; and that soluble in either hot or cold alcohol, _glutin_. I give these names and explain them, as my readers may be otherwise puzzled by meeting them in books where they are used without explanation, especially as there is another substance presently to be described, to which the name of ‘vegetable casein’ has also been applied. The gluten-fibrin is supposed to correspond with blood-fibrin, gluten-casein with animal-casein, and glutin with albumen. Their composition is as follows, which I append for what it is worth in connection with this theory, but mainly to show how small is the difference between the chemical composition of the nitrogenous constituents of animals and those of plants. I shall come to this subject again: +--------------------+---------------+---------------+--------+ | -- | Gluten-Fibrin | Gluten-Casein | Glutin | +--------------------+---------------+---------------+--------+ | Carbon | 53·23 | 53·46 | 53·27 | | Hydrogen | 7·01 | 7·13 | 7·17 | | Nitrogen | 16·41 | 16·04 | 15·94 | | Oxygen and sulphur | 23·35 | 23·37 | 23·62 | +--------------------+---------------+---------------+--------+ +--------------------+---------------+---------------+--------+ | | Blood-Fibrin | | | | -- | (Scherer) | Animal-Casein | Albumen| +--------------------+---------------+---------------+--------+ | Carbon | 53·57 | 53·83 | 53·50 | | Hydrogen | 6·90 | 7·15 | 7·00 | | Nitrogen | 15·72 | 15·65 | 15·50 | | Oxygen and sulphur | 22·81 | 23·37 | 24·00 | +--------------------+---------------+---------------+--------+ Gluten is usually described as ‘partly soluble in hot water.’ My own examination of this substance suggests that ‘partially soluble’ is a better