SALTS 227 



are best removed by the application of gasoline or benzine. | ; 

 These substances dissolve the grease, but do not remove it 

 from the clothing; for that purpose a woolen cloth should be 

 laid under the stain in readiness to absorb the benzine and the 

 grease dissolved in it. If the grease is not absorbed while in 

 solution, it remains in the clothing and after the evaporation 

 of the benzine reappears in full force. 



Cleaners frequently clean suits by laying a blotter over a 

 grease spot and applying a hot iron ; the grease, when melted 

 by the heat, takes the easiest way of spreading itself and 

 passes from cloth to blotter. 



209. Salts. A neutral liquid formed as in Section 204, by 

 the action of hydrothloric acid and the alkali solution of caus- 

 tic soda, has a brackish, salty taste, and is, in fact, a solution 

 of salt. This can be demonstrated by evaporating the 

 neutral liquid to dryness and examining the residue of solid 

 matter, which proves to be common salt. 



When an acid is mixed with a base, the result is a sub- 

 stance more or less similar in its properties to common salt; 

 for this reason all compounds formed by the neutralization of 

 an acid with a base are called salts. If, instead of hydro- 

 chloric acid (HC1), we use an acid solution of potassium 

 tartrate, and if instead of caustic soda we use bicarbonate 

 of soda (baking soda), the result is a brackish liquid as be- 

 fore, but the salt in the liquid is not common salt, but Rochelle 

 salt. Different combinations of acids and bases produce 

 different salts. Of all the vast group of salts, the most 

 abundant as well as the most important is common salt, 

 known technically as sodium chloride because of its two con- 

 stituents, sodium and chlorine. 



We are not dependent upon neutralization for the enor- 

 mous quantities of salt used in the home and in commerce. 

 It is from the active, restless seas of the present, and from 



