NEW PUBLICATIONS. 69 



If we consider the proportions in which bodies unite with each other, as represent- 

 ing the relative weights of their atoms, it would follow that the first oxide of iron is 

 composed of one atom of metal to one of oxygen ; and the second oxide, of one 

 atom of metal to one and a half of oxygen, or, rather, (to avoid the absurdity of 

 splitting an atom,) of two atoms of iron with three atoms of oxygen ; and we may 

 consider the three atoms of lead as similarly constituted. But it is not necessary 

 to involve the question of the atomic theory, which is hypothetical, with the practi- 

 cal consideration of chemical equivalents. It has been ascertained, by direct 

 experiment, that all bodies unite together chemically, in definite proportions, 

 which are fixed and invariable ; these proportions, when reduced to their smallest 

 quantities, compared to some element as a standard, are called equivalent propor- 

 tions, or combining proportions ; thus taking hydrogen as unity, the following are 

 the equivalent proportions of 



Oxygen, 8 Carbon 6 Potassium, 40 



Nitrogren 14 Sulphur, l6 Sodium 24 



Chlorine, 36 Iron 28 Lead, 104 



The equivalent proportions of all the elementary bodies have been ascertained, 

 as correctly as the present state of chemical science admits, and, although there 

 is some difference in the estimations " of different chemists, yet it seldom amounts 

 to anything very considerable. (A table of the combining proportions of all the 

 elementary bodies was exhibited in the lecture room.) 



Whenever any of the elementary bodies unite together, they unite in equivalent 

 proportions, or in multiples of those proportions ; and even when two compounds 

 unite together, the same order of definite and multiple proportions prevails ; for 

 example, there are two compounds of carbonic acid and potash ; they are composed 



1st.— Carbonic Acid, ... 22, Potash,.... 48 

 2nd.— Carbonic Acid, . 44, Potash,.... 48 



The second (bicarbonate of potash) contains twice as much carbonic acid as the 

 first. In order to arrive at the equivalent proportions of carbonic acid and potash, it 

 is necessary to refer to the equivalents of their elements, thus, carbonic acid is com- 

 posed of one equivalent of carbon, 6, and two equivalents of oxygen, 16, making 

 22. Potash is composed of one equivalent of potassium, 40, and one of oxygen, 8, 

 making its equivalent 48. 



A knowledge of the laws of combination is of the greatest utility to the practical 

 chemist. By knowing the equivalent or combining proportions, he can, with the 

 greatest ease, tell the proportions of the elements which constitute any compound, 

 the quantity of any substance necessary to decompose it, and the amount of the 

 new products. 



Mr. W. next proceeded to explain numerous applications of the laws of equiva- 

 lent proportions, and pointed out their particular use to the manufacturer, as well 

 as to the scientific chemist. He then concluded his lecture, which was evidently 

 received with great interest and satisfaction, by a most respectable audience. 



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