Agricultural and Horticultural Chemistry. 363 



phuretted hydrogen when they decay. In such cases the 

 presence of this gas is known by its exceedingly offensive 

 odor, and we are therefore warned of its presence and en- 

 abled to guard against the bad effects which it might pro- 

 duce, for it is one of the most poisonous gases known, a 

 very small quantity of it in the air producing bad effects 

 on those who respire it, and in larger quantities proving 

 fatal. The influence exerted by this gas on the animal 

 economy is tolerably well known from the experiments of 

 Thenard and Dapuytren, who exposed different animals to 

 atmospheres contaminated with various proportions of this 

 gas; and the effect produced by a small quantity in the air 

 on the human frame is very well known to chemists and 

 physiologists. 



" It is commonly believed from the few experiments which 

 have been published on this subject, such as those of Chris- 

 tison and Turner, that sulphuretted hydrogen gas possesses 

 as poisonous properties with regard to plants as it does with 

 respect to animals. I will not now bring forward the writ- 

 ten opinions published on this subject, but merely quote a 

 passage from the writings of Liebig. Speaking of the 

 refuse ammoniacal liquor of the gas works, a fluid which 

 always contains a small quantity of sulphuretted hydrogen, 

 he says : ' Now the ammoniacal liquor of the gas works 

 contains the ammonia in the form of carbonate and hydro- 

 sulphate, (sulphuret of ammonium.) The latter compound 

 is a deadly poison to vegetables, nor can we conceive that, 

 by dilution, its properties can be changed.' This statement 

 of Liebig is probably in part founded on the known effects 

 of the gas upon animals, and partly on the fact that farmers, 

 in the preparation of manures, always expose it in a heap 

 for some time, until the greater part of the sulphuretted 

 hydrogen is dissipated. 



"In the course of experiments I was led to make trial of 

 the action of some of the compounds of this gas on growing 

 vegetables, and the results I obtained were very different 

 from what I had expected. I made use of the hydrosul- 

 phuret of ammonia, the very compound described by Liebig 

 as being a 'deadly p^oison;' but in place of killing plants, 

 I found that, in small quantity, it produced decidedly ben- 

 eficial effects. In some cases, when it was applied to plants 

 in an unhealthy state from the action of other substances, 

 it had the effect of invigorating them and of restoring their 



