CS2 Reading-Course for Farmers' Wives. 



teristic property, the power to unite with fats to form soaps soluble in 

 water, and valuable as cleansing agents, or detergents as they are called. 

 Soap is a convenient and effective form in which to use the caustic 

 alkalis, as their corrosive nature is so modified as to render it useful 

 without being unduly injurious to fabrics. 



There is much difference of opinion as to which of these alkalis produces 

 the better soap. The question is settled practically in favor of the 

 sodium soap, as it can be produced at a smaller cost, and it is safe to 

 say that much on the market is sodium soap. 



Fats. Fats are compounds formed from the union of a class of sub- 

 stances known as fatty acids with glycerine, and the nature of a fat 

 depends on the fatty acids which enter into its composition. Thus, 

 in tallow, the chief fatty acid is stearic acid. Tallow, in common with 

 other fats containing relatively large proportions of stearic acid, has 

 the property of " hardness " and a high melting point. The chief fatty 

 acid in olive oil is oleic acid, which gives to it the characteristic softness 

 and low melting point of fats rich in this acid. 



When lye is mixed with a fat it breaks it up into the fatty acids 

 and glycerine of which it is composed. The lye unites with the fatty 

 acids to form a new compound, called soap, and glycerine is left as 

 a by-product in this reaction. This process is called saponification. 

 As can readily be seen, the nature of the soap formed will depend, first, 

 on the nature of the fats used, whether these are hard or soft, clean or 

 rancid; second, on the kind of alkali used, whether caustic potash or 

 caustic soda; third, on the nature and amount of im^purities contained 

 in both fat and alkali; fourth, on the completeness of the process of 

 saponification. If the operation of soap-making is not properly con- 

 ducted, the reaction between the fat and alkali is incomplete and a soap 

 is produced which contains free fat and an undue amount of free alkali. 

 Such soap is greasy, unduly caustic and a poor detergent. There 

 might be a fifth consideration — the possible adulteration of soap. It 

 is not uncommon to add some foreign, insoluble substances to soap to 

 increase its weight and bulk. In cheap soaps resin is often added as an 

 adulterant. It is rather difficult to say when resin may be considered 

 as an adulterant, for in small quantities it is of value in laundry soaps 

 as it whitens the clothing. Resin gives a brown color to soap and a 

 dark brown soap can safely be rejected ,as containing an excess of this 

 substance. 



The best advice to give the housekeeper is, to select a soap manu- 

 factured by a reliable firm and give it a trial. It is not economy 

 to use cheap and poorly made soaps in the laundry. A common mis- 



