552 



NA TURE 



[April 12, 1894 



death conning, said to his servant, " Mind what I say — I 

 am going to die. When I am dead, but not till then, go 

 to Lord George Cavendish and tell him— go." There 

 are Lavoisier and Dumas, at once men of action 

 in many departments of public life and men of thought, 

 men of the world, and men of science ; and there is 

 Faraday, the humblest, the simplest, the most accurate, 

 and the most original, of men. 



The boo'c abounds in examples of the dangers, the 

 difficulties, and the triumphs, of the scientific method. 

 We see Priestley on the verge of great discoveries regard- 

 ing the composition of water and metallic calces, but 

 held back by his devotion to that idol of the theatre, 

 phlogiston. We see Boyle meeting the statement of 

 Linus, that the mercury in the Torricellian vacuum is 

 upheld by a kind of internal cord, by measuring the 

 decrease in the volume of a portion of air caused by 

 increasing the pressure on that air, and so arriving at 

 the fundamental statement regarding the relation of 

 gaseous volumes to pressure which is known as Boyle s 

 law. 



We are able, too, to compare the thoroughness and 

 methodical application of the Germans, as shown in the 

 wo.rk and lives of Wohler and Kopp, with the brilliancy 

 and sweep of the French naturalists Lavoisier and 

 Dumas, and also with the stubborn perseverance and 

 imaginative grasp of such English men of science as 

 Dalton, Graham, Faraday, and Boyle. 



The comparison of the two great atomists, Dalton and 

 Graham, made on pp. 225-6, is succinct and suggestive. 

 But I cannot agree with the author in his apparent 

 approval of Henry's statement that imagination had no 

 part in the discoveries of Dalton. I am sure that every- 

 one who has attempted to teach the essentials of the 

 atomic theory must be convinced that without vivid 

 imagination it is impossible to gain any firm hold of this 

 great conception. The whole of Dr. Thorpe's book, 

 indeed, miy be taken as a complete refutation of the 

 vulgar mistake that the man of science has no need of 

 imagination. 



One may be repelled by the solitary, non-human life of 

 Cavendish ; but the character of Faraday, as set forth in 

 Dr. Thorpe's sketch, must attract every reader. The 

 accounts of the first meetings of Wohler with Berzelius, 

 and Dumas with Humboldt, given in the words of 

 Wohler and Dumas themselves, show that to men of 

 science too comes sometifnes the glow of hero-worship. 



Who but a Frenchman would express his joy at a 

 new discovery made in the laboratory by seizing the dis- 

 coverer and waltzing with him round the benches ! This 

 was Gay-Lussac's method. I have been present when the 

 arrival of a few tarry, evil smelling, drops of a long- 

 wished for compound has been hailed with shouts and 

 songs ; but the translation of the emotions of a chemist 

 into the poetry of movement is a higher and more 

 inspiring flight. 



The criticism givenby Dr. Thorpe of the conception that 

 underlies the hypothesis of Prout is one that chemists 

 would do well to remember. In its original form, Prout's 

 hypothesis suggested that the atoms of the elements are 

 collocations of atoms of hydrogen, and that, therefore, the 

 atomic weights of the elements are whole multiples of the 

 NC. 1276, VOL. 49] 



atomic weight of hydrogen. Dr. Thorpe very justly re- 

 marks of the work of Stas (p. 229) : 



" It may be that it demolished Prout's hypothesis in 

 its original form, but it has not touched the wider ques- 

 tion ; indeed it is very doubtful whether the wider ques- 

 tion is capable of being reached by direct experiments 

 of the nature of those of Stas, unless the weight of the 

 coinmon atom is some very considerable fraction, say one- 

 half or one-fourth, of that of the hydrogen atom." 



It seems to me that chemists have been very ready to 

 forget "the wider question " that underlies the hypothesis 

 of Prout. That wider question is : Are the elementary 

 atoms collocations of different numbers of atoms of one 

 fundamental kind of matter ? And Prof. Thorpe does 

 well to point out that this question cannot be answered 

 by measurements of the relative weights of the atoms of 

 the kinds of matter that we call elements. If the best 

 established values for the atomic weights are multiplied 

 by one hundred, all the values will be expressed in whole 

 numbers ; it is then only necessary to assume that the 

 atom of the fundamental matter is one hundred times 

 lighter than the atom of hydrogen, and, if the wider 

 question underlying Prout's hypothesis can be answered 

 by measurements of atomic weights, that question is 

 answered. The solution of the world-old enigma of the 

 unity of matter must be sought for by other methods. 



On p. 154 the author quotes from Faraday, who, when 

 writing to a scientific man at variance with another, re- 

 marked : 



" These polemics of the scientific world are very un- 

 fortunate things ; they form the great stain to which the 

 beautiful edifice of scientific truth is subject. Are they 

 inevitable .'' " 



Would it not have been better had Dr. Thorpe, re- 

 membering this wise remark made by Faraday, who was 

 the perfect representative of the true scientific student of 

 nature, omitted from his collected essays that entitled 

 " Priestley, Cavendish, Lavoisier, and La Revohition 

 Chimique " ? This essay jars somewhat. It is not in 

 harmony with the others ; it is not concerned with mat- 

 ters of universal interest ; it revives a controversy that 

 surely had better been left in forgetfulness. For is it 

 of much importance to determine whether Lavoisier 

 was or was not wholly indebted to Priestley for the 

 fact that red precipitate^ when heated, gives off a gas 

 wherein a taper burns brilliantly ? 



Lavoisier can afford to make full acknowledgment of 

 indebtedness to Priestley. Priestley discovered dephlo- 

 gisticated air ; Lavoisier gave oxygen to science. 



M. M. Pattison Muir. 



THE ORIGIN OF GLACIAL DRIFTS. 

 The Canadian Ice-Age. By Sir J. William Dawson, 

 C.M.G., F.R.S. (Montreal: William V, Dawson. New 

 York and London : The Scientific Publishing Com- 

 pany, 1893.) 



IT is continually brought to the notice of geologists 

 that the most recent period in the long history of 

 the earth is also that which excites the greatest con- 

 troversy. We can deal complacently with earth-move- 

 ments, mountain-thrusts, and submergences of half a 



