1814.] Higgins on the Atomic Theory, &c. 57 



ence of the specific gravity of those gases depends on the size of 

 their respective particles ; or we must suppose that an ultimate 

 particle of hydrogen requires two, or three, or more particles of 

 oxygen to saturate it. Were this the case, water or its constituents 

 might be obtained in an intermediate state of combination, like 

 those of sulphur and oxygen, azote and oxygen, &c. This appears 

 to be impossible ; for in whatever proportion we mix hydrogen and 

 oxygen gases, or under whatever circumstances we unite them, the 

 result is invariably the same. 



" When water is decomposed, or resolved into its constituent 

 gases by the voltaic lattery, or by atl electric machine, the above 

 pro|K)rtions are constantly obtained. 



" From those circumstances we have sufficient reason to conclude 

 that water is composed of a single ultimate particle of oxygen and 

 an ultimate particle of hydrogen, and that its atoms are incapable 

 of uniting tu a third particle of either of their constituents." 



This passage is taken, with a slight alteration, from the Compa- 

 rative View, page 36, and is given in page b~, Sec. of the work at 

 present under our consideration. Mr. Higgins terminates it with 

 the following observations, to which the attention of the reader is 

 requested : — 



" lc will, I should suppose, be needless to tell my reader that the 

 foregoing facts relative to sulphurous acid, sulphuric acid, and water, 

 suggested the first effort of ascertaining the comparative weights of 

 the particles of different elementary matter, and that the weight of 

 the atoms and molecules which they produced might readily be 

 ascertained, those facts being once established. This part of my 

 theory Mi. Dalton strictly attends to." P. 60. 



There is one other quotation which I must still make, because it 

 is a passage on which Mr. Higgins lays the greatest stress. It is as 

 follows : — 



" It has been shown by Dr. Austin that hydrogen gas suffers no 

 diminution or increase of its volume by the union of sulphur ; 

 therefore one-half of the mixed airs was hydrogen independent of 

 its sulphur ; that is, 4-±- of hydrogen gas. These 44- measures re- 

 quire 2\ measures of oxygen gas to condense them into water : 2^ 

 more of oxygen were expended in the experiment,* two of which 

 must exist in the sulphurous acid ; and as much of the azote f dis- 

 appeared, we may conclude that the remainder of the oxygen (one- 

 fourth of a measure) was expended in the formation of nitrous 

 acid. 



" From the foregoing facts it is evident that the two measures of 

 sulphurous gas contain two measures of oxygen ; and as the specific 

 gravity of sulphurous gas is double that of its constituents, excluding 



* The experiment alluded r» mt the firing; a mixture of equal bulks of (nl> 

 pboreteri hydrogen gai and Oxygen gas. A quantity of lalphoroui acid gai wa» 

 formed by the explosion. 



+ Thii azote ».is owing to ihe impurity of the oxygen t;:n employed. It had 

 been obtained irom nit 



