24 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



an example of the first case, a carrot loses 25 per cent, of its total 

 proteid on boiling. The loss in the second case is relative rather 

 than actual ; it is evident that the same bulk of food contains less 

 nutrients after the absorption of water than it did before. Thus 

 parsnips gain 15 per cent., artichokes 11 -6 per cent., and cabbage 

 8 -5 per cent, of their original weight on boiling. Consequently, it is 

 evident that a method of cooking which dispenses with the immer- 

 sion of vegetables in boiling water will economize the foodstuffs 

 present. 



Thus we have seen that the usefulness of an ordinary vegetable 

 to the human economy falls under three distinct headings, viz. : — 



1. Food value, i.e. its richness in proteid, carbohydrate, fat, and 



salts. 



2. Vitamine value. 



3. Bulk value. 



We cannot include the two latter items under any system of 

 measurement as we can the first, but their presence should be care- 

 fully borne in mind. It may be assumed that more benefit will be 

 derived from the Vitamine elements in those vegetables which are 

 eaten raw or at any rate not boiled ; and as to bulk value, it is obvious 

 that such vegetables as cabbages will possess it to a greater extent 

 than, for example, legumes. 



Food values pure and simple are expressed in terms of energy. 

 Although the analogy is a rough one, the body may be compared 

 to a steam engine. The energy required to drive the piston of the 

 latter is procured by the combustion of fuel in the furnace. In the 

 human engine food is burnt up, and the energy in that food, origin- 

 ally emanating from the sun and stored in plants, is liberated ; by 

 means of it the body performs its functions, both automatic and 

 volitional. 



The unit of energy is called the big Calorie, hereafter simply 

 named the Calorie ; it is arrived at by measuring the number of 

 litres of water raised through i° C. by burning 1 gramme of the food 

 to be tested in a bomb calorimeter. 



The values given by the main food elements are : 



In working out the relative values of these elements in a given food, 

 multiply the percentage of proteid fat or carbohydrate found on 

 analysis by the above figures, and the result will express the total 

 Calories yielded by proteid, &c, in 100 grammes of the food in question. 

 On adding together the Calories given by each constituent, the total 

 value of the food is arrived at. 



Proteid 

 Carbohydrate 



4*1 

 9*3 



4*1 Calories 



Fat 



