65$ Destruction of Insects and Vermin 



Art. VII. On the Application of the Ammoniacal Liquor of Coal 

 Gas to the Destruction of Insects and Vermin. By Robert 

 Mallet, Esq. 



Sir, 

 I have much pleasure in complying with your request 

 (Vol.VII. p. 558.), by furnishing such details concerning this 

 particular use of ammoniacal liquor, as, I imagine, will be 

 sufficient for every intelligent gardener. Ammonia is present 

 in the ammoniacal liquor, partly pure or caustic ; but, in a 

 larger quantity, in the states of sulphate and carbonate of 

 ammonia ; and I find the following to be one of the best 

 modes of finding exactly the entire quantity of pure ammonia 

 contained in a given quantity of the liquor : — 



Place 300 or 400 grains of the liquor in a small retort; 

 apply a gentle heat, and collect whatever pure ammonia is 

 present over mercury, and observe its quantity. Dilute the 

 fluid with an equal weight of distilled water ; and carefully 

 drop in either muriate of lime or of barytes, until it ceases to 

 occasion any further precipitate. Then filter and wash the 

 precipitate with pure water, add the washings to the clear 

 liquor, and evaporate the whole to dryness in a previously 

 weighed flask, applying the heat carefully, towards the end of 

 the evaporation, lest the muriate of ammonia be sublimed. Let 

 the flask and contents be again weighed; subtract the former 

 from the latter weight; and the difference will be the weight 

 of the muriate of ammonia produced by the sulphuric and 

 carbonic acids, which formed the sulphate and carbonate of 

 ammonia, quitting their base and uniting with that of the 

 muriate of barytes or lime, and the muriatic acid of the lat- 

 ter uniting with the ammonia of the former salts. The weight 

 of muriate of ammonia being known, the quantity of pure 

 ammonia may be easily estimated, every 100 parts of the 

 former containing 31*95 of the latter. 



I give this at length, to enable any gardener, who is com- 

 petent (and what gardener can pretend to understand his 

 business who is not a tolerable chemist ?), to repeat the pro- 

 cess ; which it will be well to do before using the liquor, as 

 that obtained from different gas-works contains varying quan- 

 tities of ammonia. 



Those, however, who are unable to determine the quantity 

 of ammonia for themselves, may rely safely enough on the 

 result of my experiments ; viz., 1 ft. of ammoniacal gas will be 

 produced from 11023 grains of ammoniacal liquor, at a mean 

 temperature and pressure of the atmosphere. There is no gar- 

 dener, I should hope, at the present day, who cannot find the 



