AMMONIUM SULPHIDE. 99 



care must be taken not to bring it in contact with plants. Ammonia 

 enters into the composition of certain anticryptogamic bouillies, and 

 chiefly eau celeste used to kill mildew. The good effects of this pre- 

 paration are indisputable ; but they can only be obtained by working 

 with an absolutely neutral solution, a point which does not receive in 

 the majority of cases the serious supervision which it requires. It 

 follows that mishaps occur, which should not be produced with a sub- 

 stance possessing all the properties that can be desired. Pure ammonia 

 has few applications in agriculture. However, gas liquor, which is 

 cheap, is in general use. These ammoniacal liquors kill mosses in 

 meadows and impart fresh vigour to grain crops. But in the condi- 

 tion in which they are bought these liquors are too concentrated, and 

 might kill graminaceous crops. They must be reduced by an equal 

 quantity of ordinary water-, and only 4000 litres of this mixture spread 

 per hectare (352 gallons per acre) (Noffray). The following diseases 

 are combated by ammoniacal treatment : — 



Heterodera Scliachtil, Schmidt (nematode of the beet). — Willot has 

 published very satisfactory results which he has obtained by the use 

 of ammoniacal liquors. The infested beet fields, producing, on an 

 average, 4 tons of beets per hectare, say 1-6 ton per acre, yielded 

 37 tons per hectare, say 14'4 tons per acre. In Willot's brevet the 

 nematodes succumb to the alkaline action of gas liquors, provided 

 they contain 5 per cent of ammonia. The results obtained by others 

 have not been so favourable. Hollrung, Strohmer, and Stift have, 

 in fact, energetically combated the efficacy of this treatment, their 

 experiments having given no satisfactory result. Hollrung even 

 remarks that beet seed was not capable of springing up in a soil 

 treated with ammoniacal liquor. To avoid this drawback Willot 

 follows up his ti'eatment by spraying with ordinary water. Be that 

 as it may, this treatment cannot be so efficacious as that due to Aime 

 Girard, which consists in using a strong dose of carbon disulphide, and 

 which ought always to be prefen-ed. 



Jassus sexnotatus (grain grasshopper). ^ Steglich recommends 

 ammoniacal liquor of gasworks, in which 2 per cent of soft soap is 

 dissolved, the whole diluted with an equal bulk of water, to get rid of 

 this pest. Sorauer eulogizes the good effects of this treatment, and 

 recommends spraying with a solution made in the ratio of 30 lb. of 

 soft soap and 3 gallons of commercial ammonia in 100 gallons of 

 water. Muhlberg's experiments with gaseous ammonia and am- 

 moniacal liquors to destroy the Schizoneura lanigera (woolly aphis) ; 

 Coquillet's to destroy kermes ; Voiret and Gervais's, then Mouillefert's,. 

 to combat phylloxera of the vine, have given negative results. 



19. Ammonium Sulphide, (NHJ^S. — Preparation. — Am- 

 monia forms, when combined with a semi-molecule of sulphuretted 

 hydrogen, hydrosulphide of ammonia or ammonium sulphide. 



Properties. — Ammonium sulphide is crystalline, colourless, and 

 very soluble in water. 



Use. — Dematophora necatrix, Hartig (root rot). — Dufour tried to 

 replace carbon disulphide by this substance, but the results obtained 

 were not perceptible. 



