258 



NATURE 



[April 29, 1920 



possible number of terminal — OH or — COOH 

 groups. 



For example, casein, according to the author, 

 behaves as a i6-base acid. To provide sixteen 

 terminal carboxyl groups, the molecule would 

 have to be either a branched chain, or chains 

 radiating from a centre where carbon atoms are 

 directly linked one to another. Such a mole- 

 cular structure, however, would render the de- 

 composition of the casein molecule on hydrolysis 

 into its constituent amino-acids unintelligible. 



Moreover, the form of the molecule of the poly- 

 peptides which have been prepared synthetically 

 is not open to doubt, and it is not radial, but a 

 chiain, the constituent amino-acids being joined 

 end to end. 



The amino-acids of the chain are united by a 

 CONH linkage, which may have a keto- or enol- 

 form, and it is here the author supposes that the 

 reaction with acids or bases takes place. 



Consider the simplest case — that of a dipeptide. 

 If combination with an acid or a base takes place 

 at the middle of the chain where the CONH link- 

 age is situated, and the salt ionises in solution, 

 the dipeptide molecule will form two protein ions. 

 Salts of proteins, therefore, should yield, not a 

 protein ion and a simple ion such as Na' or Cl'> 

 but two oppositely charged protein ions. 



This hypothesis is the central feature of the 

 book, which, indeed, is devoted to following out 

 its consequences. Its validity has been challenged, 

 but, whether true or false, no worker or student 

 will be the worse for learning what it leads to. 



Obviously, one consequence is that when a solu- 

 tion of the salt of a protein is electrolysed, the 

 protein should migrate to both cathode and anode. 

 But, as a matter of fact, as Hardy's observations 

 show, the protein migrates only in one direction 

 and in quite a normal way. The author recognises 

 this difficulty and attempts to meet it, but, owing 

 to a slip in the reasoning, his argument would 

 appear to upset his own theory. 



Science and Engineering. 



Engineering Education: Essays for English. 

 Selected and edited by Prof. Ray Palmer Baker. 

 Pp. ix-M85. (New York: John Wiley and 

 Sons, Inc.; London: Chapman and Hall, Ltd., 

 1919.) Price 6s. net. 



THIS is an interesting small book containing 

 addresses or portions of addresses by dis- 

 tinguished professors and consulting engineers 

 bearing on the importance of a knowledge of 

 science to engineers. Dr. Steinmetz, of the 

 General Electric Co., urges the need of a broad 

 culture, and especially of the study of Greek and 

 NO. 2635, VOL. 105] 



Latin classics, for engineers. Prof. McClenahan, 

 of Princeton University, advocates a three- or 

 four-year course of literary and scientific studies, 

 followed by a two-year technical course. Mr. 

 J. L. Harrington, a well-known engineer and 

 bridge designer, points out the necessity for a 

 thorough knowledge of English. 



" It is notorious that a technist is rarely a 

 good business man. This is partly because of the 

 "exaggerated importance he gives to technical 

 matters, but very largely because his thought is 

 clumsily expressed and awkwardly ordered." 



Mr. Harrington remarks on the frequent 

 obscurity of specifications, and tells of a con- 

 tractor who never completed a contract without 

 a lawsuit to determine the meaning of a speci- 

 fication, and who had never lost a lawsuit. Sir 

 W. H. White and Prof. Ranum, of Cornell Uni- 

 versity, write on the value of mathematics. There 

 are addresses on chemistry and physics, and a 

 distinguished consulting engineer, the inventor of 

 the obelisk dam at Niagara, built on end on the 

 shore and then toppled into the river, writes on 

 the importance of imagination. 



It strikes a reader that these addresses, each 

 advocating the claim of some one branch of 

 science, interesting as they are, would have been 

 more useful if there had been a recognition of the 

 distinction between what should be included in 

 the school course preceding the technical course, 

 in the technical course itself necessarily restricted, 

 and what extra academic self-education should be 

 expected to accompany and follow it. It may be 

 surmised that engineering students in the United 

 States do not enter on the technical course as 

 well prepared as they should be, and this is cer- 

 tainly to some extent the case here. But preachers 

 on education might remember what Stevenson 

 says of Sainte-Beuve, that he regarded all experi- 

 ence as a single great book in which to study 

 for a few years before we go hence ; and it seemed 

 all one to him whether you read in chap, xx., 

 which is the differential calculus, or in 

 chap, xxxix., which is hearing the band play in 

 the gardens. 



There is also an admirable address by Sir J. J. 

 Thomson, delivered before the Junior Institution 

 of Engineers, on the relation of pure science to 

 engineering. Sir Joseph remarks that the scientific 

 spirit has not diffused through and influenced the 

 bulk of our industries to the extent it has done 

 in one or two other countries. He traces the 

 evil to the fault of the secondary school, the 

 inefficiency of which causes the technical course 

 to be overloaded. 



" The curriculum is founded on the truly British 

 idea that our boys are not expected to learn any^ 



