173 
ascertain in what th.Q formative power of a single species or of 
a single individual consists.* * * * ***** 
6. We have thus advanced in our knowledge of the 
properties of matter to some presumably correct apprecia- 
tion of its nature. By spectrum analysis we appear to 
recognise this ponderable matter as the same throughout the 
universe. We may have to recast our list of simple sub- 
stances, or in other ways to modify our present views ; but 
we are conscious that we are now walking in the light of truth, 
and consequently cast the dreams of the past to the moles and 
to the bats. 
7. This may seem presumptuous, but will not appear so if 
it is considered that on every hand our present chemistry is con- 
firmed by fact ; and that the health, comfort, and well-being* (in 
a material sense) of the whole community are connected with 
continual recurrence to the principles of atomic proportions 
and dependence upon the unchangeable atomicity of atoms. 
8. The brilliant illumination of our streets, the cleanliness of 
the population, their succour through pharmaceutical aid, the 
colours of the dresses worn, and of the furniture decorating 
our houses, are a few out of the familiar instances in which 
chemical art is essential to our civilisation. 
9. Such being the progress of the science it has been neces- 
sary to co-ordinate our language with the use of phrases in the 
past; and also to modify words, e.g. metals, metalloids, salts, 
&c., giving a certain definite meaning to that which was before 
unfixed. This has not been easy to effect. 
I do not even think that it has been effected, for, though we 
have quite a right to invent new words, or even a new language 
to express new facts that we discover, it is a different matter 
when we invade the common privilege of mankind to express 
themselves as they will, 
“ Si volet usus 
Quern penes arbitrium esfc, et jus, et norma loquendi.”f 
10. Whilst it is not to be supposed that the common language 
* “Nec tamen onmimodis connecti posse putandum est 
Omnia : nam volgo fieri portenta videres ; 
Semiferas hominum species existere, et altos 
Interdum ramos e gigni corpore vivo 
Multaque connecti terrestria membra marinis, 
***** 
Quorum nihil fieri manifestum est ; omnia quando 
Seminibus certis certa genitrice creata, 
Conservare genus crescentia posse videmus. ” 
Lucretius, De Rerum Natura , lib. ii., lines 690, &c. 
t Horace, De Arte Poetica , 1. 71. 
