20 HEAT 



varies even though only slightly from this point, a physician 

 should be consulted immediately. The temperature 

 of the body is a trustworthy indicator of general 

 physical condition ; hence in all hospitals the tem- 

 perature of patients is carefully taken at stated 

 intervals. 



Commercially, temperature readings are extremely 

 important. In sugar refineries the temperature of 

 the heated liquids is observed most carefully, since a 

 difference in temperature, however slight, affects not 

 only the general appearance of sugars and sirups, 

 but the quality as well. 



The many varieties of steel show the influence 

 which heat may have on the nature of a substance. 

 By experiment it has been found that if hardened 

 steel is heated to about 450 F. and quickly cooled, 

 a steel is produced which is suitable for razors ; if 

 heated to about 500 F. and then cooled, the metal 

 is much coarser and is suitable for shears and farm 

 implements ; while if it is heated but 50 F. higher, 

 that is, to 550 F., it gives the fine elastic steel of 

 watch springs. 



A thermometer can be put to good use in every 

 kitchen ; the inexperienced housekeeper who cannot 

 judge of the " heat " of the oven will be saved bad 

 bread, if the thermometer is a part of her equip- 

 ment. The thermometer can also be used in detect- 

 ing adulterants. Butter should melt at 94 F. ; if it 

 does not, you may be sure that it is adulterated 

 with suet or other cheap fat. Olive oil should be 



Fi wellm7de a c l ear liquid above 75 F. ; if, above this tempera- 

 commercial ture, it looks cloudy, you may be sure that it, too, 



thermome- . , . , . , ~ 



ten is adulterated with fat. 



