410 On the Origin of the Aloviic Theory. 



This gas is much more condensed than its constituent gajcs, 

 and its specific gravity is in proportion to the degree of con- 

 densation. 



Nitrojis gas, wliose atoms contain one of azote and two of 

 oxygen, is much hghter than gaseous oxide. This struck me 

 very much while writing my Comparative Pletf, and in that 

 work I attri!)Uted it to the size of the cahirific atmospheres which 

 surrounded its atoms. This gas consists of ecjual vohimes of its 

 constituent gases. 



Nitrous gas and oxygen gas imite in the proportion of two 

 of the former to one of the latter to form red nitrous acid, which 

 contains one of azote and three of oxygen. This proves that 

 there areas many divisions or ultimate particles in the one volume 

 of oxygen as there are atoms in the two volumes of nitrous gas. 

 This gives the weight of an atom of nitrrous acid. 



When I wrote, I was well acquainted with the volumes in 

 which carburetted hydrogen and oxygen united, viz. carbnretted 

 hydrogen 5"5 and oxygen Z'J; the quantity of this oxygen that 

 was expended by the hydrogen of the gas was ascertained, and 

 the remainder was found in the carbonic acid gas formed. Cor- 

 rect deductions were drawn from this experiment, viz. that car- 

 bon unites to two portions of oxygen. It was also ascertained 

 that there were different kinds of carburetted hydrogen, and that 

 they required different quantities of oxygen to saturate them*. 

 The volumes in which azote and hydrogen united were ascer- 

 tained by Dr. Austin and Berthollet, and the degree of their 

 condensation were well known. 



The volumes in which ammouiacal gas and muriatic acid gas, 

 ammoniacal gas and sulphurous acid gas, animoniacal gas and 

 carbonic acid gas, unite so as to saturate each other, were well 

 known to me and to a few more in England, before I published 

 on the subject of chemistry. 



From the foregoing facts it is clear that there was nothing 

 new in Gay Lussac's important discovery of his theory ofvoluweSy 

 as the Doctor is pleased to call it. If he could give it to his 

 friend Dalton, he would not transfer it to a foreigner, — a fo- 

 reigner no doubt of considerable celebrity in chemical science. 



In this history of the Atomic Theory, the Doctor states that 

 the celebrated Berzelius, having compared the quantity of oxy- 

 gen in the base of a salt with the ox\gen of its acid, found that 

 they always bore a simple relation to each other. " They were 

 either ecjual, or the oxygen in the acid was twice as much as that 

 in the base, or thrice as much, or four times as much, &c. If 



* See Dr. Higgins's Experiments and Observations on Acetous .Acid, &c. 

 printed in 1786, p. 288. I studied with the Doctor at tliis time, and as- 

 sisted in making all the experiments contained in that work. 



the 



