398 Notices respecting New Books. 



author attempt? to show that, as a scientific explanation of the con- 

 stitution of matter, it is of little or no value. The kinetic theory of 

 gases is condemned without reservation, as not even satisfying the 

 conditions of a scientific theory and as based upon ontological 

 assumptions. The doctrine of the conservation of energy is con- 

 sidered to be sound ; and the chapter which is devoted to its exami- 

 nation shows an intimate acquaintance at least with the history of 

 the subject. A detailed criticism of the validity of the author's 

 conclusions (for there is much to be said against them) would be 

 impossible within the limits of a review ; and therefore this will 

 not be attempted here ; but one or two positive errors and miscon- 

 ceptions will be noticed. In the first place, it is incorrect to say 

 (p. 23) " that with few exceptions scientific men of the present day 

 deem the validity of the mechanical explanation of the phenomena 

 of nature to be, not only unquestionable, but absolute, exclusive, 

 and final. They believe that this validity is not conditioned, either 

 by the present state of human intelligence, or by the nature and 

 extent of the phenomena which present themselves as objects of 

 investigation." The reverse of this is nearer to the truth. A man 

 of science, in the capacity of a scientific investigator, is logically 

 compelled to consider no explanation or theory as final, but to be 

 prepared at any moment to abandon an explanation which should 

 prove to be insufficient or at variance with facts, in favour of 

 another which more adequately accounts for them. This is what 

 all scientific men hold and are bound to hold, as Liebig expressed 

 it in a passage actually quoted by the author in another part of 

 the book, " The secret of all those who make discoveries is that 

 they regard nothing as impossible."' Throughout the book the 

 author seems to lose sight of the necessary tentativeness of all scien- 

 tific theories. Under the head of the Atomic Theory the author 

 discusses the doctrine of the indestructibility of matter. In Chap- 

 ter II. he states that the true correlate of motion is not matter, but 

 mass ; and hence this term is used where ordinarily the word matter 

 is employed; but when discussing the indestructibility of matter in 

 Chapter VII. we find that he uses this term, and not indestructibility 

 of mass, which is really what chemists mean. The current doc- 

 trine is first stated, "That the constancy of mass is attested by the 

 balance, which shows that neither fusion nor sublimation, neither 

 generation nor corruption, can add to or detract from the weight 

 of a body subjected to experiment. TA'hen a pound of carbon is 

 burned, the balance demonstrates the continuing existence of this 

 pound in the carbonic acid, which is the product of combustion, and 

 from which the original weight of carbon may be recovered. To 

 test the correctness of this interpretation we may be permitted 

 slightly to vary the method of verifying it. Instead of burning the car- 

 bon, let us simply carry it to the summit of a mountain or remove it 

 to a lower latitude : is its weight still the same ? Kelatively it is : 

 it will still balance the original counterpoise. But the absolute 

 weight is no longer the same. This appears at once if we give 

 to the balance another form, taking a pendulum instead of a pair 

 of scales." What the author means by talking about "absolute 



