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which together make up the weight of an integrant particle of oxalic acid.

According to these proportions, 100 parts of oxalie acid is composed of

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numbers which do not indeed exactly correspond with the result of the preceding analysis, but which approach sufficiently near it to give the reasoning employed considerable probability at least, if it does not lead to certainty.

We may now examine the decomposition which takes place when oxalate of lime is exposed to heat. Let an atom of oxygen be w, an atom of carbon c, and an atom of hydrogen h An integrant particle of oxalic acid may be represented by 4 w + 3 c + 2 h. We may represent the composition and weight of an integrant particle of each of the substances into which oxalic acid is decomposed by heat, by the following symbols and num

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We

c weight 16.5 c + 2 h............ 6.5'

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C....... 10.5

w + h........... 7

4.5

may now conceive 3 particles of oxalic acid to be decomposed at once, and to resolve themselves into these substances, in the following proportions:

4 particles

4 particles of carbonic acid......... = 8% + 4 c

2

2

2

1

3

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Total............. 12 w + 9 c + 6 h

oxalic acid ............... = 12 w + 9c + 6 h

We see that such a decomposition is possible. It remains only therefore to see whether the weights of these substances, which result from this hypothesis, correspond with the preceding analysis. Now,

4 particles of carbonic acid weigh... 4 x 16.5 66

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Reducing these proportions to 100 parts of acid, and joining together the two inflammable gases, the numbers come out as follows:

Carbonic acid ........ 55.70 we actually obtained 59.53 Inflammable air

28.69

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24.28

11.51

4.68

100.00

It is impossible to expect exact correspondence between the theory and hypothesis, till the numbers representing the weights of the elementary atoms be ascertained with more rigid accuracy than has hitherto been done. I satisfied myself with taking the nearest round numbers,

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numbers, which are sufficient at least to show an evident approximation to the proportions obtained by experiment.

V. Composition of Sugar, and Formation of Oxalic Acid.

When a compound body is decomposed, and resolved into a number of new substances, the products are almost always simpler, or consist of integrant particles, composed of fewer atoms than the integrant particles of the original body. Thus, though oxalic acid is composed of 9 atoms, none of the products evolved, when that acid is decomposed by heat, contain more than 3 Hence it is probable that sugar is a more compound body than oxalic acid, because nitric acid resolves it into a variety of new compounds, one of which is oxalic acid. It may be worth while to examine the action of nitric acid on sugar, and the formation of oxalic acid, more closely than has hitherto been done, as the investigation will furnish some data for estimating the composition of sugar.

atoms.

Two hundred grains of pure crystallised sugar being treated with diluted nitric acid in the usual way, yielded 200 cubic inches of carbonic acid, 64 cubic inches of nitrous gas, and 70 cubic inches of azotic gas. But these numbers, though the result of a good many experiments, are not to be considered as very exact. The uncertainty depends upon the property which the solution has of producing more gas after the sugar is decomposed, at the expense of the oxalic acid formed. Now, it is difficult to stop at the precise point.

The whole weight of oxalic acid, which can be obtained from 200 grains of sugar, amounts to 116 grains. If the experiment be properly conducted, the whole of the sugar is decomposed, or at least the quantity of resisiduary matter is small.

From

From the preceding statement, there is reason to conclude that 100 grains of sugar, when decomposed by nitric acid, yield,

Grains.

1. Oxalic acid crystals 58 grains, or real acid.... 45 2. Carbonic acid 100 cubic inches, equivalent to 46.5 while these are evolved obviously by the decomposition of the nitric acid.

Grains.

1. Azotic gas 35 cubic inches equivalent to to.... 10.62 2. Nitrous gas 32 cubic inches equivalent to... 10.85 Now, as nitric acid contains no carbon, it is obvious that the oxalic acid formed, and the carbonic acid evolved, must contain the whole carbon contained in 100 grains of sugar.

Grains.

45 grains of oxalic acid contain of carbon.... 14.40 46.5 grains of carbonic acid contain of ditto.. 13.02

Total .................... ..... 27.42 therefore 100 grains of sugar contain 27 grains of carbon.

The azotic gas and nitrous gas must have been originally in the state of nitric acid, and must have given out oxygen when they were evolved. But nitric acid is composed of

Oxygen.

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Therefore they must have parted with 29.5 grains of oxygen. We are at liberty to suppose that the whole of this oxygen went to the formation of carbonic acid. Now, 46.5 grains of carbonic acid are composed of

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From this it appears, that in the carbonic acid'there were 4 grains of oxygen more than was furnished by the nitric acid. I confess I am disposed to ascribe this surplus to errors in the experiments, and to believe that the whole of the oxygen of the carbonic acid was furnished by the nitric acid. This being admitted, it follows that the carbon of the carbonic acid, and the whole constituents in the oxalic acid, were furnished by the sugar. These are as follows:

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If this total be subtracted from the 100 grains of sugar. used, there will be a remainder of 41.9 grains. As this quantity of the sugar has disappeared, and is no where to be found among the products, we must suppose that it has assumed the form of water. Now 41.9 grains of water are composed of

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Adding these quantities to the preceding products, we obtain the composition of sugar, as follows:

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