( 94 ) 



richness in ammonia, and therefore the pro- 

 portion of sulphate of iron must vary with the 

 proportion of ammonia ; generally speaking, 

 however, according to Schattenmann, 5 to 7 

 ] bs. suffice to saturate 25 gallons putrid matters. 

 The period of saturation can be readily ascer- 

 tained by adding a drop of the solution of red 

 prussiate of potassa to one of the liquor; as 

 soon as there is an excess of copperas, (iron 

 salt,) Prussian blue is formed, and this is a 

 certain sign that the jnatters are saturated, 

 and that there is an excess of sulphate of iron. 



The disinfecting liquor is poured into the 

 privy wells through the openings, by which 

 they are emptied, and well incorporated by 

 thorough stirring. 



Schattenmann very properly recommends 

 that neither vegetable debris, or meat, or fish 

 be thrown into the sinks, as their putrefaction 

 generates a peculiar infectious odor difficultly 

 neutralized by metallic salts. 



The disinfection of privy wells by sulphate 

 of iron or other metallic salts, has the double 

 advantage of contributing to the public health, 

 and of securing to their contents, all its value 

 and force as a manure by reason of the ammo- 

 nia which it contains. In fact, the ammonia- 



