83 
Dr. Thomson on Oxalic Acid. 
determined,* it appears that the weight of an integrant par- 
ticle of oxalic acid must be represented by the number 39.5. 
Now, what number of atoms of oxygene, carbon, and hydro- 
gen, go to constitute an integrant particle of oxalic acid ? We 
have assigned the relative weights of each of these atoms, 
and we have ascertained the relative proportions of the respec- 
tive elements of oxalic acid. From these data it is easy to 
solve the problem. An integrant particle of oxalic acid con- 
sists of 9 atoms combined together, namely, 4 atoms of oxygen, 
3 of carbon, and two of hydrogen. 
4 atoms of oxygen weigh 4 *6 =24 
3 atoms of carbon - - 3 x 4.5 = 13.5 
2 atoms of hydrogen - 2x1 =2 
Total 2,9-5 
which together make up the weight of an integrant particle 
of oxalic acid. 
According to these proportions, 100 parts of oxalic acid is 
composed of 
Oxygen - - 61 
Carbon - - 34 
Hydrogen - -5 
100 
numbers which do not indeed exactly correspond with the 
result of the preceding analysis, but which approach suffi- 
ciently near it to give the reasoning employed considerable 
probability at least, if it does not lead to certainty. 
* For these weights, and the method of determining them, I refer the reader to my 
System of Chemistry, 3d Edition, III. 619. The numbers which I have there assign- 
ed are, I am persuaded, rather too low. 
