CHEMISTRY AND USES OF THE POTATOE. 23 



(80.) We thus perceive that as an article of diet the 

 potatoe is invaluable, as it contains hydrogen, carbon, 

 nitrogen, phosphorus, sulphur, iron, and lime ; all elements 

 required for nutrition. 



(81.) Potatoes can be cooked either by boiling, steam- 

 ing, baking, or frying, the only point requiring atten- 

 tion being the application of the heat, which should be 

 managed in such a manner that all parts may be cooked 

 equally, and not one part overdone before the other is 

 warm. 



(82.) Potatoes may be made into bread according to 

 Parmentier. ' He first boils them and reduces them to a 

 very fine tough paste by a rolling-pin, and then mixes with 

 this an equal weight of potatoe starch. He states that 

 this mixture makes a very white, well raised, pleasant 

 bread. 



(83.) Wheaten bread in London generally contains 

 potatoes, and I am informed that they are used in the fol- 

 lowing manner : The potatoes are generally placed in 

 cold water and boiled for one hour ; they are then taken 

 out and well mashed ; a quantity of warm water is then 

 added with the yeast, and this is allowed to stand four or 

 five hours. The mixture is then strained through a fine 

 sieve, and half the flour is added, and worked up to form a 

 sponge. This sponge is allowed to stand about six hours, 

 after which it is made into bread. Donovan states that 4 

 cwt. of flour will bear 5 stone of potatoes. Potatoes are 

 also used for boiled and baked puddings, cakes, &c. 



(84.) Not only for food, but also as a medicine, is the 

 potatoe valuable. It is found of great efficacy when used 

 for scurvy ; and Dr. Baillie has lately discovered, at the 

 Penitentiary, that its efficacy is not impaired by boiling. 



