422 ORGANIC CHEMISTRY. 



same effect. But its action in this case is due to a 

 double decomposition, in which a floating soda soap is 

 formed, chloride of potassium remaining in solution. 

 Soaps may be also made without the use of water, by 

 combining oil or fat with melted potash. 



1049. LINIMENTS, &c. Soaps are soluble 



How are trans- 

 parent soaps in alcohol, forming the tincture of soap 



which is used for bruises. With the ad- 

 dition of camphor, this tincture forms opo- 

 deldoc. Transparency is imparted to soap by the evap- 

 oration of an alcoholic solution of the well dried mate- 

 rial. Liniments are soaps prepared from ammonia and 

 oil by the simple agitation of the materials. 



1050. PROPERTIES OF SOAPS. Soaps 



Explain the 



cleansing ac- which are prepared, as above seen, from 



tion of soap. ^ &nd ^ haye the property Q f dissol- 

 ving more of the same material. On this property 

 their cleansing effect principally depends. When they 

 are dissolved, a portion of the alkali becomes free by 

 the substitution of water as base. This free alkali 

 adds to the cleansing effect, by its own affinity for the 

 oils and other organic matter. Alkalies alone are not 

 equally effectual ; they tend to shrink the fibre of cloth, 

 and thus protect it against a perfect purification. The 

 strength of the tissue is at the same time gradually im- 

 paired. 



MILK, BUTTER, &c. 

 1051. MILK. Milk is analogous to 



What is the . T i , 



composition of blood in compositon, as is implied in the 

 milk? office which it fulfills in the nutriment of 



