SIR B. C. BRODIE ON THE CALCULUS OE CHEMICAL OPERATIONS. 
57 
Chloride of ethylene .... 
av 2 C 2 
Chloride of acetyl 
av 2 c% 
Chloracetic acid 
av 2 c% 2 
Chloriodide of ethylene . . 
a. 3 %coz 2 
oc 2 v 2 ci 
Hydrocyanic acid 
avx 
vn 
Methylamine 
(t 3 VX 
u 3 vn 
Trimethylamine 
a 5 vx 3 
a 3 v 3 n 
It is thus evident that the Laputian philosophers might have proceeded a long way 
indeed in the study of the metamorphoses of the compounds of carbon, and yet take a 
very different view of the nature of these compounds to that taken by ourselves. In 
their eyes the group of hydrocarbons would appear as compounds of hydrogen and 
the element acetylene, of which they would possess in benzol an allotropic modification. 
Besides these they might have innumerable compounds of acetylene and their other 
elements, of the kind indicated in the Table. 
Proceeding with their deductive investigations, they would arrive at the law of even 
numbers, and applying this critical test to the compounds of acetylene, would arrive at 
the following equations : — 
2 a?z =3 oc-j- az 2 , 
2 a 2 z 3 — a - j- 3a« 2 , 
2 aV= 3 a -f- 3 cms 2 , 
cc 3 z 4 =a-{- 2az 2 , 
2a 2 zx 2 = 2a 4- az 2 -f a^ 2 , 
2 a 2 zf = 3a;£ 2 -f - a* 2 , 
2aV£ 2 | = a + 2utf -f- cm 2 -f£ 2 , 
2 a 2 X z 2 ^ = ci + a X 2 + 2a* 2 + 2£ 2 , 
2 u 3 %a)z 2 = 2 a-\- ctf 2 -J- acj 2 -f- 2 ax 2 , 
The Laputian philosophers may be assumed to have had great reliance on their 
deductive processes, and would doubtless have said at once that these facts afforded 
a solid ground of preference in favour of their hypothesis a — indeed that the other 
hypothesis was relatively untenable. Nevertheless we may believe them to have felt 
some satisfaction when, on descending from their floating island to our earth, we showed 
them the process by which acetylene was manufactured by Berthelot from hydrogen 
and carbon, and thus turned their hypothesis into a demonstrated truth. 
There is, however, a difficulty in the way of the unqualified acceptance of hypothesis 
a, of a very real character, namely that it does not , prima, facie, appear to be in perfect 
concordance with facts. Now the facts to which this remark applies are of two classes : — • 
(1) The assumed densities of gases which are not in accordance with either of the two 
hypotheses a. and a 2 , and (2) assumed densities which are not prima facie in accordance 
