REVIEW. 
487 
it should, under the circumstances of the formation of sulphurous anhydride, be satisfied 
with only two atoms of oxygen, is surely anomalous. In the former case the sulphur 
must be a hexad, in the latter a tetrad. Not so, says the author, sulphur is always a 
hexad, but in sulphurous acid two bonds combine with each other and are latent, the 
arms are shaking hands. In this way all radicals and compounds are figured as being 
in a happy state of union with each other, dancing about with arms intertwined, often 
changing partners but seldom or never alone. “ It is scarcely necessary to remark that 
no such material connections exist, the bonds which actually hold together the atoms of 
a compound being in all probability, as regards their nature, much more like those 
which connect the members of our solar system.” 
The nomenclature of this work is, we think, of less value than the notation. Per¬ 
manence, in a name, is a quality of more importance than scientific chemists seem to 
imagine. A name which fairly individualizes a body and includes no theory is far more 
valuable than one descriptive of constitution; for the latter involves theory, and hence 
is ever liable to alteration. We owe small thanks to those compilers of old Pharma¬ 
copoeias who adopted chemical names which include the syllables proto, mono, sesqui, 
di, bi, tris, ter, etc. Nine chemists and druggists or medical men out of ten do not 
know how to find out whether calomel or corrosive sublimate is meant when proto¬ 
chloride of mercury is mentioned. Hence we fear that this work, in which such terms 
are extensively adopted, will not find much favour with pharmaceutical or medical 
students. Indeed, when we see that chrome-alum demands such a name as dipotassic 
dichromic tetrasulphate, and remember that the name wfill possibly be altered half-a- 
dozen times within the next thirty years, we feel strongly inclined to think, with Sir 
Benjamin Brodie, that purely scientific chemists should be content with formulge, and 
leave the giving and using and retaining of names to the followers of applied chemistry. 
On the other hand, the use of the syllables ous and fc, which frequently occur in this 
book, is attended by many advantages. They include scarcely any theory, and as simply 
pointing to the lower and higher of the two classes of salts which a metal may afford, 
are useful and permanent guides. We shall soon meet with several examples of diffi¬ 
culty in nomenclature similar to that already referred to regarding corrosive sublimate; 
in such cases the names mercurous and mercuric chloride, ferrous sulphate, ferric chloride, 
etc. etc., will be invaluable. 
The author recognizes five modes of chemical action, the second and third of which 
are w'hat were formerly known as single and double decomposition. In illustration of 
the former he gives the following equation;— 
2 H Cl -I- Nao = 2 Na Cl -f Ho. 
This is not a happy example, for the molecule of sodium contains two atoms, which be¬ 
come separated, each combining with an atom of chlorine to form two distinct molecules 
of sodic chloride. The molecules of sodium and hydrochloric acid being both decom¬ 
posed, this illustration belongs to the third and not to the second mode of chemical 
action,—it is a case of double, not single decomposition. The following equation we 
should regard as an example of single decomposition:— 
2 H Cl -f Zn = Zn CL. + Hg. 
For the molecule of zinc contains but one atom. By the way, the author would say of 
the molecule of zinc that it is monatomic, and sodium diatomic, meaning that the mole¬ 
cules contain one and two atoms respectively: this atomic quality of molecules we 
should expect to be termed their atomicity, just as the elastic character of a thing is 
termed its elasticity. But in this work the words atomic and atomicity instead of being 
naturally related to each other are divorced, and mean opposite things ; atomic relating 
to the number, atomicity to the value of atoms in molecules. The atomic character of 
zinc, for example, is 1, its atomicity 2; we do not object to the author’s use of the 
word atomic, but we do to atomicity,—the latter would have been advantageously re- 
nlaced by Hofmann’s term quantivalence. We hold a somewhat similar objection to 
ttie word anhydride. Hydrides are bodies containing radical hydrogen, hydrates bodies 
containing water. But in this, and some other modern chemical works, bodies without 
water are termed anhydrides, as if without hydrogen; we would prefer to see and hear 
them described as anhydrates. 
The above are the only faults we have to find with these ‘Notes.’ _ We regard'the 
work as an important addition to the literature of chemistry, and cordially recommend 
it to those of our readers who desire to keep pace with the onward progress of chemical 
science. 
