EXERCISES
1. Why is ironing less necessary than washing?
2. What are the chief cleansing and purifying agents?
3. Explain the difference between hard and soft water. Remedies for hardness?
4. What is soap, and how does it act?
5. Why do we blue and starch clothes?
6. Describe the methods of forcing water through clothes.
7. Why are clothes boiled?
8. What are some of the labor saving devices and methods in washing and ironing?
9. Why must clothes be sorted according to fabrics?
10. What are the essentials of a good washing machine?
11. Make a list of the cleansers and chemicals necessary to have on the laundry shelf.
12. Obtain price lists and estimate the cost of simple but sufficient laundry equipment.
13. Obtain a laundry list from a commercial laundry. Make a list of the articles washed at home, and compare cost with the cost of putting out clothes, estimating fuel, cleansers, labor, and some wear and tear of apparatus.
APPENDIX
_CLa.s.sIFICATION OF FOODSTUFFS_
Elements required by the body
Carbon Hydrogen Oxygen Nitrogen Sulphur Phosphorus Iron Calcium Magnesium Pota.s.sium Sodium Chlorine Iodine (traces) Fluorine (traces) Silicon (traces)
Foodstuffs furnishing these elements
Proteins--furnish carbon, hydrogen, oxygen, nitrogen, sulphur, and sometimes phosphorus and iron
Fats--furnish carbon, hydrogen, and oxygen
Carbohydrates--furnish carbon, hydrogen, and oxygen
Mineral matter--furnishes phosphorus, iron, calcium, magnesium, sodium, pota.s.sium, chlorine, iodine, fluorine
Water--furnishes hydrogen and oxygen
General functions of these foodstuffs
To supply energy
To supply building material
To regulate body processes
Special functions of each foodstuff
Proteins--supply energy; also nitrogen, sulphur, and sometimes phosphorus for body building
Fats--supply energy in the most concentrated form
Carbohydrates--supply energy in the most economical form
Mineral matter--supplies building material and helps to regulate body processes
Water--supplies necessary material (about 60 per cent of body being water) and helps to regulate body processes
Examples of food materials rich in each of the foodstuffs
_Proteins_ Eggs Milk Cheese Lean meats Fish
_Fats_ Cream b.u.t.ter Meat fats Vegetable oils Nuts Yolk of egg
_Carbohydrates_ Cereals and cereal products Potatoes and other starchy vegetables Chestnuts Sweet fruits Sugar
_Mineral matter_ Milk Green vegetables Fruits Whole wheat and other whole cereal products Egg yolk
_Water_ Fresh fruits Fresh vegetables Milk Beverages, including water as such
Digestion of the foodstuffs
Having seen what each of the foodstuffs does in nourishing the body, we may now see how they are prepared for the use of the body in the digestive tract.
=Digestion of carbohydrate.=--The simplest carbohydrate is a sugar which cannot be broken up into other sugars. Such a simple sugar is called a monosaccharid. There are two common in foods, glucose and fructose; a third, galactose, is derived from more complex sugars. Two simple sugars united chemically make a double sugar or disaccharid; thus cane sugar or sucrose will yield glucose and fructose, while milk sugar or lactose will yield glucose and galactose, and maltose will yield two portions of glucose. These three disaccharids are the only common ones. Starches, dextrins, and cellulose or vegetable fiber are made of many simple glucose groups, and are hence called polysaccharids. All carbohydrates to be used by the body must be reduced to simple sugars. Glucose needs no digestion therefore, but the double sugars must be split by enzymes into two simple sugars in the intestinal juice, one for each kind, namely, sucrase (sucrose-splitting), maltase (maltose-splitting) and lactase (lactose-splitting). The digestion of starches and dextrins begins in the mouth, where amylase (starch-splitting) changes starch first to dextrin and finally to maltose, and maltase may change a little of the maltose so formed into glucose. In the stomach there are no enzymes acting on carbohydrates, but the digestion may continue under the influence of swallowed saliva for a time. In the pancreatic juice there is another amylase, which completes the splitting of starch to maltose, and then the intestinal maltase can reduce this to glucose, which will be absorbed.
Cellulose cannot be digested and simply serves to add bulk to the diet.
=Digestion of fat.=--A fat is made up of two parts, one a fatty acid, the other glycerol. Fat cannot be absorbed by the body until it is split into these two parts. A fat splitting enzyme is called a lipase. There is none in the mouth; one in the stomach works only on fat in the state of emulsion; the most powerful is found in the pancreatic juice. Since fat cannot be digested in the mouth nor to any great extent in the stomach, it is bad to have food coated with it, for the protein and carbohydrates will have to wait till the fat is digested away, before they can be digested; that is, till the intestine is reached. This is one reason why pastries and fried foods are hard to digest.
=Digestion of protein.=--There are no enzymes in the mouth acting on protein. In the stomach, the hydrochloric acid helps to make it soften and swell, and then pepsin begins its digestion. Protein, like fat and carbohydrate, can be subdivided into smaller and smaller portions, finally being reduced to a form which the body can absorb, namely, amino acids, of which there may be 17 or 18 kinds from a single protein.
The digestion in the stomach produces chiefly large fragments of the original protein, called proteoses. In the pancreatic juice is a powerful enzyme called trypsin, which digests proteins, first to fragments, next smaller than proteoses, called peptones, and finally breaks these peptones into amino acids. In the intestinal juice is another enzyme called erepsin, which also forms amino acids from proteoses and peptones, thus finishing any digestion of protein left incomplete by the trypsin.
Fate of the absorbed foodstuffs