URINE. 143 



lime will unite with the ammonia to form sul- 

 phate of ammonia, and this salt will remain in 

 the soil and not be volatilized. 



But a simpler way still is to mix the gyp- 

 sum with the putrefied urine, and thus effect 

 the double decomposition above described be- 

 fore distributing it on the soil. 



The quantity necessary will of course de- 

 pend on the quantity of carbonate of ammonia 

 the urine may contain, and this not only varies 

 with every stage of putrefaction, but depends 

 also on the way in which it has been kept ; and 

 again, on the quality of the urine itself, no very 

 definite quantity therefore can be named. But 

 an easy way of knowing how much gypsum to 

 put to a certain quantity of urine is to add it 

 constantly at intervals of a few hours (taking 

 care to stir the mixture well occasionally) as 

 long as any volatile smell, similar to hartshorn, 

 escapes, the absence of which will be a sure test 

 that the ammonia has lost its volatile property, 

 and has become, to use a chemical and expres- 

 sive term, fixed. 



Chloride of lime may be used for the like 

 purpose, but being more expensive than the 

 gypsum, it would not of course be resorted to. 



Dried peat, tanner's bark, sawdust, turf and 

 other similar substances, may be also used 

 for this purpose, but the gypsum is decidedly 

 preferable. 



Sulphuric acid, the oil of vitriol of com- 

 merce, may also be advantageously used to fix 

 this salt, and to do so nothing more is neces- 

 sary than to mix a sufticient quantity of this 

 acid with the putrefied urine until almost all 



