662 SEC. 13. CHEMISTRY. 







1850, and vol. vi., p. 227, 1851. The experiments were, however, 

 continued to 1858, inclusive. John Bennet Lawes. 



The balance, which was made by Mr. Ocrtling, of London, was constructed 

 to turn with less than one grain, when loaded Avith 50 Ibs., or even more, 011 

 each side. This it accomplished, but it was found that the quantity of water 

 given off by the plants during their growth was so great that such accurate 

 weighing was not necessary. In fact, during the whole period of growth, as 

 much as from 15 to 20 Ibs. of water was in some cases given off from a single 

 jar of plants, and during the most active periods of growth as much as from 

 1,500 to 2,000 grains per day. In the earlier experiments the vessels in 

 which the plants were grown were made of glass, but afterwards of zinc, 

 There was no opening at the bottom for drainage. The top was closed by a 

 glass plate, firmly cemented to the rim, but having a hole in the centre for the 

 plants to grow through, and another, smaller one, nearer the side by which to 

 supply weighed quantities of water as needed, but which was, at other times, 

 closed by a cork. To prevent, as far as possible, evaporation from the soil 

 other than through the plant itself, small pieces of glass were laid over the 

 centre hole, close up to the stems of the plants as they grew. Each jar held 

 about 42 Ibs. of soil. A standard leaden counterpoise was kept in the weight 

 pan, and only the deviations above or below its weight were determined ; a set 

 of weights, from 10,000 grains down to one-tenth of a grain, being provided 

 for the purpose. The weighings were generally taken at intervals of 10 days, 

 but sometimes at shorter periods. 



The list of plants experimented upon included wheat, barley, beans, peas, 

 clover, mangold wurzel, turnips, and various evergreen and deciduous trees. 



2742. Case of Casts of White Silesian Sugar-beet, illus- 

 trating the influence of different manures on the amount of produce, 

 and on the per-centages of dry matter and of sugar in the roots. 

 First season of the experiments, 1871. John Bennet Lawes. 



2743. Table of Average Results obtained on growing the 

 crop (sugar-beet) five years in succession on the same land. 



John Bcnnct Lawes. 



The experiments were conducted on the farm of John Bennet Lawes, Esq., 

 Rothamsted, near St. Albans. 



2744. Apparatus used in an investigation by Messrs. Lawes, 

 Gilbert, and Pugh, to determine whether plants assimilate free or 

 unconibined nitrogen ; with drawings of some of the plants grown. 

 See Philosophical Transactions, Part 2, p. 493, 1859 ; and 

 Journal of the Chemical Society, new series, vol. i. ; Entire 

 Series, vol. xvi., 1863. John Bennet Lawes. 



The tap being opened, and water allowed to flow from a raised reservoir 

 into the large stoneware Woulfe's bottle, air passes from it by the small 

 leaden exit tube, through two glass Woulfe's bottles containing sulphuric 

 acid, then through the long tube filled with fragments of pumice saturated 

 with sulphuric acid, and, lastly, through a Woulfe's bottle containing a 

 saturated solution of ignited carbonate of soda ; and, after being so washed, 

 the air enters the glass shade, from which it passes by an exit tube through 

 an eight-bulbed apparatus containing sulphuric acid, by which communica- 

 tion with the unwashed external air is prevented. Entering the shade at 

 the Bide opposite to this exit tube is a tube for the supply of water or solutions 



