528 Reviews. [ July, 
logically commences with the Physical Properties of the Metals—and 
some General Considerations on Metallurgical Processes, proceeding to a 
full examination of Fuel, and then entering on the special Metallurgies 
of the useful Metals. 
The development of Heat is necessarily a most important study to 
the Metallurgist. Heat of high degrees of intensity is required—and 
this must be produced with the utmost economy. The characteristics 
of various kinds of Fuel—such as Wood, Charcoal, Peat, Lignite or 
Brown Coal, Coal, Coke, and Anthracite, are therefore matters of 
interest. Hence Dr. Percy has devoted a large portion of his first 
volume to their consideration. We should be wanting in justice if we 
failed to state our high appreciation of the original matter,—experi- 
ments made with the most scrupulous care, and deductions drawn with 
philosophical acumen,—which marks this division of our author’s 
labours. 
That, notwithstanding all that has been written on the subject of 
Coal, and all the examinaticns to which this Fuel has been subjected ~ 
by Chemist, Geologist, and Naturalist, we should be unable to answer 
the question, “ What is Coal?” is a sad reflection on European philo- 
sophy. In 1853 a remarkable trial took place at Edinburgh before 
the Lord Justice General and a special jury to try this question. The 
result is well put by Dr. Percy :-— 
“At the trial there was a great array of scientific men, including 
chemists, botanists, geologists, and microscopists ; and of practical gas engi- 
neers, coal-viewers, and others, there were not a few. On the one side it 
was maintained that the mineral was coal, and on the other that it was a 
bituminous schist. The evidence, as might be supposed, was most conflict- 
ing. The judge accordingly ignored the scientific evidence altogether, and 
summed up as follows :—‘The question for you to consider is not one of 
motives, but what is this mineral? Was it coal in the language of those 
persons who deal and treat with that matter, and in the ordinary language 
of Scotland ? because to find a scientific definition of coal after what has been 
brought to light within the last five days, is out of the question. But was it 
coal in the common use of that word, as it must be understood to be used 
in language that does not profess to be the purest science, but in the ordi- 
nary acceptation of business transactions reduced to writing? Was it coal 
in that sense? That is the question for you to solve.’ The jury found it 
was coal. Since this trial the same mineral has been pronounced not to be 
coal by the authorities of Prussia, who accordingly have directed it not to 
be entered by the custom-house officers as coal.” * 
While these paragraphs are being written the question is again 
before the Courts. Evidence equally as conflicting as that given on 
the former trial has been tendered by the men of science on this. 
Judgment has again been given in the plaintiffs favour, and for the 
third time the Boghead mineral is decided to be a coal. This trial 
furnishes another example of the degradation of science, whenever its 
students are induced to use their ingenuity as Special Pleaders in a 
Court of Law. Dr. Percy says, ‘‘ In the present state of science I do 
not believe it possible to propose an exact definition of the term coal.” 
eAVolsiep. to. 
