o Dr. Wollaston's Synoptic Scale 
the actual prevalence of that law of multiple proportions by 
which the atomic theory is best supported, and it is in fact to 
Mr. Dalton that we are indebted for tlie first correct obser- 
vation of such an instance of a simple multiple in the union of 
nitrous gas with oxygen. In his endeavours to determine the 
composition of the atmosphere, he found that the quantity of 
oxygen contained in loo measures of common air would com- 
bine with either 3b or 72 measures of nitrous gas, according 
to certain variations in the mode of conducting the experi- 
ment.* 
Chemists in general, however, appear to have been by no 
means duly impressed with the importance of this observation 
of Mr. Dalton, till they were in possession of other facts 
observed by Dr. Thomson and myselfj'f* in a more tangible 
form, with regard to neutral and superacid or subacid salts, 
which could be made the subjects of more deliberate and less 
equivocal experiments; and it is, perhaps, owing to the repe- 
tition and confirmation of them by M. Berthollet, J that they 
have attracted the attention of other chemists, who are now 
ready to admit that the term binacid correctly expresses the 
relation of many superacid salts to neutrals consisting of the 
same ingredients. Since that time the additional instances in 
which the same law has been observed to prevail, are become 
so numerous, especially with regard to different degrees of 
oxidation, that we have the greatest reason to presume that 
the colourless contains about five of dephlogisticated to one of phlogisticated air. 
Comparative View, p. 84. 
• Manchester Mem. Vol. V. — Nich. Journal, Vol. XIII. p. 433. 
f Phil. Trans. 1808, p. 74. — Ditto, p. 96. 
X Mem. d’Arcueil, Tome II. p. 470. 
