Farmyard Manure. 21 



removed the excess of this gas by drying the powder at a very 

 moderate heat. 



With these various materials, the following experiments were 

 instituted : 



1. Added to 6 ounces of liquid manure 2 ounces of a strong 

 solution of sulphite of magnesia and sulphite of lime. No 

 apparent effect was produced. Added 2 more ounces of the 

 same solution. The smell remained unchanged. 



By keeping this mixture of liquid manure with sulphite of 

 magnesia and lime, for three weeks in a bottle, the original dis- 

 agreeable smell of the liquid manure remained unaltered, thus 

 showing that pure sulphites have not the power of removing the 

 bad smell from putrescent liquids. 



2. 50 grains of M'Dougall's powder were finely pounded in a 

 mortar, and gradually mixed with 5 ounces of liquid manure. 

 The bad smell of the latter disappeared instantly. An addition 

 of 5 ounces more of liquid manure ; the liquid became sweet 

 to the smell after a few minutes. 10 additional ounces were next 

 mixed with the disinfected liquid, and thus altogether 20 ounces 

 of liquid manure were mixed with 50 grains of M'Dougall's 

 powder. 



After some time the bad smell disappeared altogether, but, at 

 the same time, ammonia was set free, as shown by litmus paper 

 suspended in the neck of the bottle. 



3. The same experiment was tried, with the substitution for 

 M'Dougall's powder of 50 grains of prepared gas-lime. 



The result was similar to that obtained in the second experi- 

 ment ; the only perceptible difference being that, by using gas- 

 lime, the liquid manure, which had originally a dark greenish 

 brown colour, was rendered more transparent and lighter coloured 

 than by using M'Dougall's powder. 



4. Another experiment was tried with 20 ounces of liquid 

 manure and 50 grains of slaked lime, mixed with some gas-tar. 



The putrescent smell was instantly removed, and the liquid 

 became bright and colourless like water. Ammonia was 

 given off. 



5. i Ib. of M'Dougall's powder was treated with 20 ounces of 

 distilled water, and filtered. 



The clear liquid was coloured yellow, smelt like the powder, 

 and had a weak alkaline reaction. 



4 ounces of this solution were mixed with 4 ounces of liquid 

 manure ; the bad smell disappeared after some time. 4 ounces 

 more of liquid manure were added ; the smell was not entirely 

 removed. 



Kept in a bottle for 2 days, the liquid was not entirely 

 deodorized. 



