instead of saying the combination of 2 atoms of Sulphuret of Arsenic containing 3 atoms of Sulphur, with one atom of Sulphuret of Potassium (Kali) with the least dose of sulphur.’
Berzelius goes on to say that the English chemists had found themselves unable to find any substitutes for his formulæ when they translated his papers.
Our English chemists have not generally adopted the notation of oxygen by dots; but have employed commas or full stops and symbols (, or . and +), to denote various degrees of union, and numerical indices. Thus the double sulphate of copper and potash is Cu O, SO3 + KO, SO3.
What has been said is applicable mainly to inorganic bodies (as salts and minerals)[70]. In these bodies there is (at least according to the views of many intelligent chemists) a binary plan of combination, union taking 363 place between pairs of elements, and the compounds so produced again uniting themselves to other compound bodies in the same manner. Thus, in the above example, copper and oxygen combine into oxide of copper, potassium and oxygen into potash, sulphur and oxygen into sulphuric acid; sulphuric acid in its turn combines both with oxide of copper and oxide of potassium, generating a pair of salts which are capable of uniting to form the double compound Cu O, SO3 + KO, SO3.
[70] Fownes’s Chemistry. Part iii.
The most complicated products of inorganic chemistry may be thus shown to be built up by this repeated pairing on the part of their constituents. But with organic bodies the case is remarkably different; no such arrangement can here be traced. In sugar, which is C12 H11 O11, or morphia[71], which is C35 H20 NO6, the elements are as it were bound together into a single whole, which can enter into combination with other substances, and be thence discharged with properties unaltered; the elements not being obviously arranged in any subordinate groups. Hence the symbols for those substances are such as I have given above, no marks of combination being used.
[71] Fownes’s Chemistry, p. 354.
It is perhaps a consequence of this peculiarity that organic compounds are unstable in comparison with inorganic. In unorganic substances generally the elements are combined in such a way that the most powerful affinities are satisfied[72], and hence arises a state of very considerable permanence and durability. But in an organic substance containing three or four elements, there are often opposing affinities nearly balanced, and when one of these tendencies by some accident obtains a preponderance and the equilibrium is destroyed, then the organic body breaks up into two or more new bodies of simpler and more permanent constitution.
[72] See Hist. Ind. Sc. b. xiv. c. 3.
There is another property of many organic substances which is called the Law of Substitution. The 364 Hydrogen of the organic substance may often be replaced by Chlorine, Bromine, Iodine, or some other elements, without the destruction of the primitive type or constitution of the compound so modified. And this substitution may take place by several successive steps, giving rise to a series of substitution-compounds, which depart more and more in properties from the original substance. This Law also gives rise to a special notation. Thus a certain compound called Dutch liquid has the elements C4 H4 Cl2: but this substance is affected by chlorine (Cl) in obedience to the law of substitution; one and two equivalents of hydrogen being successively removed by the prolonged action of chlorine gas aided by sunshine. The successive products may be thus written