Abbildungen der Seite
PDF
EPUB

the following is the order in which the combinations may take place, beginning with the most simple: namely,

=

=

I atom of A+ 1 atom of B-1 atom of C, binary.
I atom of A+ 2 atoms of B I atom of D, ternary.
2 atoms of A+ 1 atom of B-1 atom of E, ternary.
I atom of A+ 3 atoms of B-1 atom of F, quaternary.
3 atoms of A+I atom of B = 1 atom of G, quaternary.

=

etc., etc.

The following general rules may be adopted as guides in all our investigations respecting chemical synthesis:

Ist. When only one combination of two bodies can be obtained, it must be presumed to be a binary one, unless some cause appear to the contrary.

2d. When two combinations are observed, they must be presumed to be a binary and a ternary.

3d. When three combinations are obtained, we may expect one to be a binary, and the other two ternary.

4th. When four combinations are observed, we should expect one binary, two ternary, and one quaternary, etc.

5th. A binary compound should always be specifically heavier than the mere mixture of its two ingredients.

6th. A ternary compound should be specifically heavier than the mixture of a binary and a simple, which would, if combined, constitute it; etc.

7th. The above rules and observations equally apply, when two bodies, such as C and D, D and E, etc., are combined.

From the application of these rules, to the chemical facts already well ascertained, we deduce the following conclusions; 1st. That water is a binary compound of hydrogen and oxygen, and the relative weights of the two elementary atoms are as I: 7, nearly; 2d. That ammonia is a binary compound of hydrogen and azote, and the relative weights of the two atoms are as I : 5, nearly; 3d. That nitrous gas is a binary compound of azote and oxygen, the atoms of which weigh 5 and 7 respectively; that nitric acid is a binary or ternary compound according as it is derived, and consists of one atom of azote and two of oxygen, that nitrous "He is a compound similar to nitric

[graphic]

oxygen, weighing 19; etc., etc. In all these cases the weights are expressed in atoms of hydrogen, each of which is denoted by unity.

In the sequel, the facts and experiments from which these conclusions are derived, will be detailed; as well as a great variety of others from which are inferred the constitution and weight of the ultimate particles of the principal acids, the alkalies, the earths, the metals, the metallic oxides and sulphurets, the long train of neutral salts, and in short, all the chemical compounds which have hitherto obtained a tolerably good analysis. Several of the conclusions will be supported by original experiments.

From the novelty as well as importance of the ideas suggested in this chapter, it is deemed expedient to give plates, exhibiting the mode of combination in some of the more simple cases. A specimen of these accompanies this first part. The elements or atoms of such bodies as are conceived at present to be simple, are denoted by a small circle, with some distinctive mark; and the combinations consist in the juxtaposition of two or more of these; when three or more particles of elastic fluids are combined together in one, it is to be supposed that the particles of the same kind repel each other, and therefore take their stations accordingly.

This plate [on the following page] contains the arbitrary marks or signs chosen to represent the several chemical elements or ultimate particles.

[blocks in formation]

21. An atom of water or steam, composed of 1 of oxygen and I of hydrogen, retained in physical contact by a strong affinity, and supposed to be surrounded by a common atmosphere of heat; its relative weight=

22. An atom of ammonia, composed of 1 of azote and I of hydrogen....

23. An atom of nitrous gas, composed of 1 of azote and 1 of oxygen... ...

24. An atom of olefiant gas, composed of I of carbone and I of hydrogen

8

6

12

6

[merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][subsumed][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][ocr errors]

25. An atom of carbonic oxide composed of 1 of carbone and I of

oxygen ...

I

26. An atom of nitrous oxide, 2 azote + I oxygen.

27. An atom of nitric acid, I azote + 2 oxygen...

[ocr errors]

28. An atom of carbonic acid, I carbone + 2 oxygen.....

29. An atom of carburetted hydrogen, I carbone + 2 hydrogen.. 30. An atom of oxynitric acid, I azote + 3 oxygen..

...

31. An atom of sulphuric acid, I sulphur + 3 oxygen...

12

17

[ocr errors]

32. An atom of sulphuretted hydrogen, I sulphur + 3 hydrogen... 16

33. An atom of alcohol, 3 carbone + 1 hydrogen..

34. An atom of nitrous acid, I nitric acid + 1 nitrous gas.

35. An atom of acetous acid, 2 carbone + 2 water.......

36. An atom of nitrate of ammonia, I nitric acid + 1 ammonia + I

water ...

37. An atom of sugar, I alcohol + I carbonic acid.

35

Enough has been given to show the method; it will be quite unnecessary to devise characters and combinations of them to exhibit to view in this way all the subjects that come under investigation; nor is it necessary to insist upon the accuracy of all these compounds, both in number and weight; the principle will be entered into more particularly hereafter, as far as respects the individual results. It is not to be understood that all those articles marked as simple substances, are necessarily such by the theory; they are only necessarily of such weights. Soda and potash, such as they are found in combination with acids, are 28 and 42 respectively in weight; but according to Mr. Davy's very important discoveries, they are metallic oxides; the former then must be considered as composed of an atom of metal, 21, and one of oxygen, 7; and the latter, of an atom of metal, 35, and one of oxygen, 7. Or, soda contains 75 per cent. metal and 25 oxygen; potash, 83.3 metal and 16.7 oxygen. It is particularly remarkable, that according to the abovementioned gentleman's essay on the Decomposition and Composition of the fixed alkalies, in the Philosophical Transactions (a copy of which essay he has just favoured me with) it appears that "the largest quantity of oxygen indicated by these experiments was for potash 17, and for soda, 26 parts in 100, and the smallest 13 and 19."

GAY-LUSSAC

JOSEPH LEWIS GAY-LUSSAC was born at St. Léonard, France, Dec. 6, 1778. He was educated at home until 1794 and entered the Ecole Polytechnique at the end of 1797. Late in 1800 he was assigned to Berthollet as an assistant. It is said that he was scrupulously exact in recording the results of the experiments he made, and that Berthollet after looking over the results, which did not at all accord with his expectations, exclaimed, "My young man, it is your destiny to make discoveries for yourself. Hereafter be my associate. I wish to be your father in science and I am sure it is a title I shall some day be proud of."

Early in 1802 he seems to have noted that gases expand alike when heated from zero to 80 degrees. In 1804 he ascended 23,000 feet in a giant balloon in order to make experiments on temperature and magnetism. In 1805 he traveled in Italy and Germany. The next year he was admittted to membership in the Academy.

In 1809 he announced his law of multiple proportions that gases combine with each other by volumes in integral ratios, I to I, I to 2, 2 to 3, and that the volume of the product also bears a simple relation to that of each constituent. This law was fiercely attacked for a time, but eventually won acceptance.

In 1810 and 1811 he was busy examining the constituttion of such organic substances as sugar, starch, wax, acetic acid, etc. During this time there was considerable rivalry between himself and Humphrey Davy, as both of them had been investigating along the same line in discovering boron, iodine, etc.

Most of the rest of his life was spent in researches in practical chemistry. He died May 9, 1850.

[graphic]
« ZurückWeiter »