There are two scales used in thermometry, the Fahrenheit and the Centigrade. The former is generally used. However, since many of the scientific calculations are made using the Centigrade scale it is wise for the nurse to understand how to translate one to the other.
Centigrade has 0° as the freezing point and 100° as the boiling point, while Fahrenheit has 32° as freezing point and 212° as boiling point. To change Fahrenheit to Centigrade it is necessary to subtract 32 from 212 in order to make the freezing points correspond. This would read 212 -32 = 180° F. = 100° C; hence a degree Centigrade represents 5/9 of a degree Fahrenheit.
To change Centigrade to Fahrenheit it is necessary to remember that every Fahrenheit degree is 9/5 times as large as the Centigrade and the addition of 32° must also be made. For example: Change 105° F. to Centigrade: 105°-32° × 5/9 = 41° C. Change 50° C. to Fahrenheit: 50° × 9/5 + 32° = 90° + 32° = 122° F.
FOOTNOTE:
[28] “Diseases of Nutrition and Infant Feeding,” by Morse and Talbot.
CHAPTER V
FOOD MATERIALS AND THEIR PREPARATION
Dairy Products.—Milk, cream, and other dairy products form such an important part of the invalid dietary that they require especial care in their selection. “Certified Milk” is the safest. This is protected by special inspection. The methods and standards governing the production and distribution of certified milk were adopted by the American Association of Medical Milk Commissions, May 1, 1912. The sanitary condition of the dairy, the cleanliness of the vessels into which the milk is placed, the health of the milkers, and a surety that no member of their family with whom they come in contact has any kind of contagious disease, are all obligatory. The feed for the cows and the purity of the water given them to drink must be inspected and made to conform to the standard laid down for certified milk. The milk of sick cows and those having tuberculosis is absolutely condemned. The composition of certified milk is standardized as follows: the fat standard shall be 4%, with a permissible range varying from 3.5% to 4.5%. The proteins shall be 3.5%, with a permissible range varying from 3% to 4%. Certified milk shall not contain more than 10,000 bacteria to the cubic centimeter when it is delivered. This inspection and standardizing necessarily raises the price of certified milk above that of milk not so rigidly cared for, and when the additional expense makes it impossible for the patient to afford certified milk, the only thing to do is to be sure of the reliability of the dealer from whom the milk is purchased and the cleanliness of the dairy from which it is procured. Buttermilk and butter are the milk products which require some attention as to selection. The former grows sour with age and the odor of advanced fermentation and decomposition is readily recognized. Sweet butter, butter without salt, is less apt to be old when purchased than the salted variety, as the flavor of rancid fat is unmistakable in butter which has not been especially treated.
Milk.—Milk is without a doubt the most valuable food in the invalid dietary, furnishing not only a highly nutritious beverage, but likewise acting as a carrier of additional nourishment when such is necessary. Its form, its lack of definite flavor and odor, all add to its value as a food in sickness. Milk is one of the few foods which includes in its composition all of the chemical combinations known as foodstuffs. The carbohydrates, comprising 4.88% to 5% of the solids in milk, occur as lactose or milk sugar. This sugar belongs to the disaccharide group, and is, in the majority of cases, readily digested by even the most delicate digestive apparatus. This form of sugar lends itself particularly well as a reinforcing agent, and is generally used in such cases as typhoid fever, etc. The fat in milk, comprising 4% of the solids and occurring as butter fat (cream), is made up chiefly of olein and of palmitin, with smaller amounts of stearin and from 5% to 6% of its composition in the form of butyric acid (the fatty acid to which butter owes its name and flavor) and traces of other fatty acids, as well as small quantities of cholesterin, lecithin, and a yellow coloring matter.