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ROYAL HORTICULTURAL SOCIETY. 



which exist in water (eight times the weight of oxygen), so that 

 they may be regarded as hydrated carbons. These assumptions, 

 however, by no means accord with the very perfect modern ana- 

 lyses of starch, sugar, flax, and cotton, by Prout, Herrmann, 

 Henry, and Tire, since all these substances show a greater or less 

 excess of oxygen above hydrogen. "Wheat-starch, according to 

 Prout, contains 41 C, 49 '42 O, and 6" 18 H, being an excess of 

 02 of oxygen # . Potato-starch, according to Hermann, contains 

 37*6 C, 55*76 0, 6-64 H, or 264 excess of oxygen over the con- 

 stituents of water. Cotton-wool contains, according to lire, 

 4211 C, 52-83 O, and 5-06 H, or an excess of 12-35 O, which 

 cannot be taken into the plant by the condensation of water. 



In all other component parts of vegetables the elementary 

 matters differ most decidedly from the proportions of oxygen and 

 hydrogen in water, so that their origin from the condensation 

 of water or the formation of hydrates seems quite impossible. 



These vegetable matters may conveniently be divided into three 

 sections. 



1. Matters which contain a great excess of oxygen as vegetable 

 acids. Citric acid contains, according to Berzelius, 41*36 C, 

 54*83 O, 3 8 II, an excess of 24'43 of oxygen. Malic acid, ac- 

 cording to Liebig, contains 42-11 C, 56*14 O, 1*75 H, an excess 

 of 42*14 O. Tartaric acid, according to Berzelius, 35*98 C, 

 60*21 O, 3*80 H, an excess of 29*75 of oxygen. 



2. Matters which contain an excess of hydrogen, as resin, fat, 

 and ethereal oils. Olive-oil, according to Gray-Lussac and Thenard, 

 contains 77*21 C, 9 42 O, 13*36 H, an excess of 12*18 H. Cam- 

 phor (a solid ethereal oil) contains, according to Liebig, 81*76 C, 

 8*53 O, 9*70 H, an excess of 8*63 H. Bees'-wax contains, ac- 

 cording to Gray-Lussac, 81*78 C, 4*63 O, 14*07 H, an excess of 

 11*9 H. 



Coal is one of the substances which has a decided excess of 

 hydrogen. According to Tire it contains 75-76 per cent. C, 

 5-8-10 per cent. O, 5-6 per cent. H, 1-2 per cent. IN". Since 

 eight parts of oxygen in weight go to one of hydrogen in the 

 formation of water, coal must contain 5-6 per cent. H, with 

 40-48 per cent. O, if it is a hydrated carbon ; there is, therefore, 

 an excess of 4-5 per cent. H. 



3. There are, moreover, vegetable matters which contain hy- 

 drogen without oxygen, and are therefore anything rather than 



* There is evidently something wrong about the figures here, as there is a de- 

 fect of oxygen to the amount "02. — Tr. 



