560 SULPHURETTED HYDROGEN. 



vegetables, such as Peas, Beans, and Lentils. A third is always 

 present ia the juices of all plants; and it is found in the 

 greatest ahundance in the juices of those which we use for the 

 purposes of the table." — Liebig. 



This sulphur is obtained from the sulphates contained in 

 soil. Hence the value of such substances as sulphate of lime 

 (gypsum), of sulphate of ammonia formed when sulphuric acid 

 is brought into contact with carbonate of ammonia in dung- 

 hills, and of the foetid gas called sulphuretted hydrogen, which 

 is formed abundantly in the decomposition of animal matter. 



Sulphur alone has been used to advantage as a manure. Not teing 

 soluble in water, it cannot pass as suob into the plants; still, if it is 

 well pulverised, it will be converted (by attracting the oxygen of the 

 air) into sulphuric acid, which wiU then unite with any bases of the 

 soU into a sulphuric salt. This process will most probably easiest take 

 place when the soil contains much carbonate of Ume, as the lime dis- 

 poses (by its great affinity for sulphuric acid) the sulphiir to unite 

 quicker with the oxygen of the air. It is, however, yery doubtful if 

 sulphur ooiild be used as a manure on a large scale. In addition to this 

 it is asserted that experiments have proved the utility of sulphurets 

 (combinations of sulphtir with the metals of Hme, soda, or potash) as 

 manuring substances. It is also stated that they destroy worms and 

 insects, most probably by developing sulphuretted hydrogen gas by 

 their decomposition. We have seen before, that gypsum and ashes 

 often contain sulphuret of calcium and sulphuret of potassium. Further 

 experiments have to prove whether these substances can ever be use- 

 fully employed in agriculture on a large scale. I have often used 

 potashes, containing much sulphuret of calcium, as a manure, but the 

 effect seemed neither good nor bad. — Sprengel. 



The great objection to manures containing sulphuretted hydrogen 

 is its intolerable fcetor. " The offensive exhalations produced by putre- 

 fying matters arise," says Sehattenmann, "principally from the ilying 

 off of carbonate of ammonia and sulphuretted hydrogen gas : but if a 

 solution of sulphate of iron is thrown among such matters, a double 

 decomposition immediately takes place ; the sulphuric acid of the 

 sulphate of iron combines with the ammonia, and converts it into 

 a fixed salt; the iron combines with the sulphur, and forms a sul- 

 phuret of iron. The unpleasant smell of ammoniacal vapour and of 

 sulphuretted hydrogen disappears immediately, and the putrefying 

 matter that is acted on retains nothing more than a feeble odour, 

 which is not in the, slightest degree disagreeable." The objection to 

 this mode of disinfecting manure is that the phosphoric acid of munure 

 is likely to be converted into an iron phosphate and thus rendered 



