Observations on Liebig's " Organic Chemistry^ 111 



Every person, lie says, who has entered a manufactory of beet- 

 root sugar, must be astonished at the great quantity of ammonia 

 volatihsed with the steam, which is a source of loss of sugar ; 

 the escape of ammonia causing the neutral juice to become acid, 

 and the acid changing part of the sugar into crystallisable 

 grape sugar and syrup. Distilled flowers and medicinal ex- 

 tracts contain ammonia. The unripe fruit of the almond and 

 peach, tobacco leaves, the exudations of vines, beet root, unripe 

 blossoms and fruits, the juices of birch, maples, &c., all yield 

 anmionia. He gives an analysis of different kinds of wheat, 

 differing as far as from 12^ to 26^ per cent in the gluten they 

 contain ; in winter wheat the gluten is only 3*33 per cent. 



Animal manure, he says, increases the gluten, as well as the 

 quantity of grain. Wheat grown in a soil manured with cow- 

 dung, which contains little nitrogen, yielded only about 12 per cent 

 of gluten; while that grown in a soil manured with human urine 

 yielded as much as 35 per cent : he does not state the increase 

 of produce. Putrid urine, he says, is best, as the urea in the 

 urine is converted into carbonate of ammonia by the heat and 

 moisture of jiutrefaction. Guano, the dung of sea-fowls, used 

 as manure in Peru, producing great fertility, is composed of 

 urate, carbonate, &c., of ammonia. Manure acts only, he says, 

 by yielding ammonia. That urine is a powerful manure is, in 

 practice, well known ; and that ammonia is very needful seems 

 undoubted; but that the ammonia only is useful cannot be said : 

 it is principally in the state of carbonate of ammonia, which 

 contains one atom each of carbonic acid, water, and ammonia. 

 The urine also contains salts of potash, soda, and lime, which 

 he afterwards considers as important ; also mucus, and other 

 animal substances. The guano contains excrement, and, analysis 

 says, fatty matter. The salts of nitric acid can give little except 

 the nitrogen and their bases, which may neutralise and absorb 

 carbon and organic matter. If these salts produced fertility in 

 sterile barren sands, then might we see more of the exclusive 

 benefits of nitrogen. Most soils contain much undecomposed 

 organic matter ; it is rated very high in fertile soils by Sir H. 

 Davy. Ammonia uncombined has been thought poisonous to 

 plants, as fresh urine and hot dung have been found to kill many 

 plants : perhaps, as it seems to act principally as a stimulant, it 

 may be poisonous only when not diluted with water, which 

 prevents its being in excess, and is well known as a source of 

 safety. 



All plants, he says, contain azotised substances, and no 

 animal can live without nitrogen or azote. Horses fed on po- 

 tatoes get weak, as potatoes contain little nitrogen : rice also 

 contains little ; and a much greater quantity of that food is 

 required than wheat. As animals assimilate nitrogen, their 



