1 1 Oil Chemical Equivalents. 



figures, or weights of those particles of bodies which are not in 

 contact, our numerical expressions ought to relate only to the 

 results of experiments." 



He conceives that the calculations will be much expedited, 

 and the formulae rendered more simple, by considering the smallest 

 proportion of any combining body, namely, that of hydrogen, as 

 the integer. This radical proportion of hydrogen is the Trgcux)] 

 iiAij of the ancient philosophers. 



It has been objected by some, to our assuming hydrogen as 

 the unit, that the numbers representing the metals would be- 

 come inconveniently large. But this could never be urged by 

 any person acquainted with the theory of numbers. For in 

 what respect is it more convenient to reckon barium 8*75 on the 

 atomic scale, or S-75 x 16 = 140 on Sir H. Davy's scale of 

 experiment ? or is it any advantage to name, with Dr. Thomson, 

 tin = 7'375, or to call it 118, on the plan of the EngHsh philo- 

 sopher ? If the combining ratios of all bodies be multiples of 

 hydrogen, as is probable, why not take hydrogen as the unit ? 

 I tliink this question will not be answered in the negative, by 

 those who practise the reduction of chemical proportions. The 

 defenders of the Daltonian hypothesis, that water consists of one 

 atom oxygen to one atom hydrogen, may refer to Dr.Wollaston's 

 scale, as authority for taking oxygen as the imit. But that ad- 

 mirable instrument, which has at once subjected thousands of 

 chemical combinations to all the dispatch and precision of logome- 

 tric calculation, is actually better adapted to the hydrogen unit, 

 than to the oxygen. For if we slide down the middle rule, till 

 10 on it stand opposite to 10 hydrogen on the left side, every 

 thing on the scale is given in accordance with Sir H. Davy's 

 system of primary proportions, and M. Gay-Lussac's theory of 

 gaseous combination. This valuable concurrence, as is well 

 pointed out by Dr. Prout, we lose, by adopting the volume of 

 oxvgen as radix. 



In the first part of the Phil. Transactions for 1814 appeared 

 Dr. Wollaston's description of his scale of chemical equivalents, 

 an instrument which has contributed more to facilitate the ge- 

 neral study and practice of chemistry than any other invention 

 of man. His paper is further valuable, in presenting a series of 

 numbers denoting the relative primary proportions, or weights 

 of the atoms of the principal chemical bodies, both simple and 

 compound, determined with singular sagacity, from a general 

 review of the most exact analyses of other chemists, as well as 

 his own. 



The list of substances which he has estimated, are arranged 

 on one or other side of a scale of numbers, in the order of their 

 relative weights, and at such diblances from each other, according 



to 



