ORGANIC SUBSTANCES. 673 
I have already stated that such a rule already exists in the 
laws for the combinations of elements in inorganic nature. But 
it frequently happens, that even with the aid of the best guide, 
we are unable to obtain clear ideas. We must then be satisfied 
with the empirical composition, and defer establishing the ra- 
tional, until our knowledge is sufficiently ripe to enable us to do 
so. When that is the case all will immediately admit and ac- 
knowledge its correctness. To increase, in the mean time, the 
number of imaginative theories is only to retard instead of ad- 
vance the progress of science. 
Which views of the rational composition of organic bodies can 
be considered as corresponding with the laws of combination ob- 
served in inorganic nature? That is the question which I shall 
now endeavour to answer. 
The idea of compound radicals and of their union with oxy- 
gen, sulphur, salt radicals, &c., is, as I have previously shown, 
the best guide for our judgement which we can take from inor- 
ganic nature. It is not my intention to develope this idea here. 
That has already long been done, and I refer for further par- 
ticulars to the fifth German edition of my ‘ Manual of Chemistry,’ 
vol. i. S. 672. 
But this idea, presupposing even that it is correct, as some 
experiments tried for the purpose seem to prove, instead of un- 
veiling to our view all the mysteries of organic nature, as Dumas 
conjectured, rather discovers to us nothing at all concerning 
them. The number of compound radicals which we have as yet 
been able to establish with any degree of certainty is also very 
small. 
If in every compound of carbon and hydrogen, or of carbon, 
nitrogen and hydrogen with oxygen, we were to consider all that 
is not oxygen as a given radical, we should be led into quite as 
erroneous an opinion, as when, in sulphate of oxide of formyle 
(Melsen’s acide sulfacétique), we consider all that which is not 
oxygen as the radical of the acid ; for the sulphuric acid contained 
in it, is united in quite a peculiar manner, or, as we express it, 
is conjoined with oxide of formyle, which accompanies the acid 
in all its combinations. In the edition of my ‘ Manual, quoted 
above at page 459, vol. i., I have given the theoretical views 
concerning this class of compounds. They occur generally, 
and we have always reason to expect them, whenever the num- 
ber of oxygen atoms in a compound atom is greater than 7,. 
