112 



DRAININGS. 



well-known properties, it occasions the foam or froth 

 of bottled ale. In drainings this acid is combined 

 partly with the potash and soda they contain, partly 

 with the ammonia generated by putrefaction, and 

 yields its place to the more powerful sulphuric acid. 

 The question may, perhaps, be started, why this acid 

 does not, like sulphuric acid, combine so strongly 

 with ammonia as to deprive it of its odor and vola- 

 tility. To such an inquiry we may answer, that 

 carbonic acid is itself a volatile and at the same time 

 very feeble acid, incapable of perfectly neutralizing 

 the ammonia, and forming with it a salt which is 

 volatile and of very pungent odor, — a salt in which 

 the ammonia, as it were, still distinctly glimmers 

 through. To be convinced of this, it is only neces- 

 sary to smell the carbonate of ammonia, met with in 

 commerce under the name of salts of hartshorn 

 (which might also be called volatile-drainings salt), 

 and to place a portion of it in some warm place ; it 

 has a very pungent odor, because the basic proper- 

 ties of the ammonia are not entirely concealed by 

 the acid, and after some time the ammonia will fly 

 off and escape, on account of the facility with which 

 it can assume a gaseous or aerial form. 



Fourth Experiment. — In order to obtain proof that 

 the white salt acquired in the preceding experiment 

 by the evaporation of the hartshoi*n when mixed with 

 sulphuric acid, that is, the sulphate of ammoniay really 

 contains ammonia, let it be brought into contact 

 with some quicklime^ in such a manner that a thick 



