DRAININGS. Ill 



siderable, is entirely prevented. With 1 lb. of sul- 

 phuric acid thus mixed with drainings, full IJ lbs. of 

 sulphate of ammonia were readily procured, or, ex- 

 pressed in money, for l^d. from 7^d. to 9d. worth are 

 obtained. The sulphuric acid does not in any way 

 obstruct the beneficial or forcing operation of the 

 ammonia upon plants, but heightens it rather, as 

 many experiments made in Saxony during the last 

 few years abundantly show. A celebrated English 

 farmer, Mr. Harcourt, who has instituted many ex- 

 periments upon this point, remarks that he obtains 

 the best results by adding 1 lb. of sulphuric acid to 

 150 lbs. of drainings, and has derived by an expendi- 

 ture of X 2 5s. in sulphuric acid an increase of hay 

 amounting in value to <£ 14 12s. 6d. above that from 

 land treated with an equal quantity of drainings, 

 but without sulphuric acid. This exceedingly com- 

 mendable mode of manuring meadow-land has been 

 employed with the happiest consequences in Switzer- 

 land from time immemorial, with the simple differ- 

 ence that green vitriol (sulphate of iron) is there sub- 

 stituted for sulphuric acid. With equally good ef- 

 fects, gypsum also might be used. Both these substan- 

 ces contain sulphuric acid in combination (the green 

 vitriol 32 per cent., the gypsum 46 per cent), which 

 acts in the same way as when free or uncombined. 



The strong effervesence which takes place upon 

 the admixture of sulphuric acid with drainings pro- 

 ceeds from the escape of carbonic acid, a kind of air 

 familiar to every one, inasmuch as, amongst other 



