238 



NATURE 



\yuiy lo, 1879 



sense ought to show them otherwise ; but when the 

 author has had some years' practical experience, he will 

 undoubtedly acknowledge that in scientific experiments 

 very little reliance is to be placed on the common sense 

 of beginners. The author says : — 



"About one-fourth of the combustion tube is filled with 

 copper oxide, the sugar weighed in a little glass tube, and 

 shaken into the combustion tube and thoroughly mixed 

 with the oxide by raking them together by a wire. The 

 remainder of the tube is filled with oxide ; or the sugar 

 may be put in a platinum boat that will pass into the 

 tube." 



As an alternative, for what may the sugar be put in a 

 platinum boat ? It appears from the text that the boat 

 is to be employed instead of filling up the " remainder of 

 the tube with oxide." No further reference is made to 

 the method of determining the C and H in organic com- 

 pounds except on p. 1 1, where we are told that in the 

 presence of nitrogenous substances the products of com- 

 bustion must be passed over heated metallic copper, and 

 we have failed to find a single hint to enable the student to 

 determine the C and H in the presence of CI, Br, I, S, or 

 alkaline metals. All the processes given in the book 

 supposing them to be intelligible to a beginner, are utterly 

 inadequate. 



Referring to the determination of nitrogen, the author 

 states (p. 12) : — 



" The ammonia process answers, except in cases where 

 the nitrogen occurs in the form of nitric acid or cyanogen, 

 when this element must be estimated by volume. This 

 method is applicable in all cases. A combustion tube of 

 about 32 inches long is taken, rounded like a test tube at 

 one end. This tube is filled with some carbonate that, 

 when heated, will give off carbonic anhydride, such as 

 manganous carbonate, magnesite or hydric sodic-car- 

 bonate, and some mercuric oxide. A weighed portion of 

 the substance for analysis, with upwards of forty times its 

 weight of a mixture of oxide of copper and mercury, the 

 rinsings of the mortar, a plug of asbestos, then about 4 

 inches of cupric oxide, asbestos and a layer of about 8 

 inches of metallic copper. The end of the combustion 

 tube is drawn out and connected with a bent delivery 

 tube, dipping beneath the mercury in the trough. When 

 all is ready the carbonate in the tube is heated to 

 generate a current of carbonic anhydride to drive out all 

 the air. 



" The metallic copper and copper oxide are heated 

 simultaneously, and when the escaping gas is free from 

 air, insert the end of the delivery tube through the tubu- 

 lure of the vessel," &c., &c. 



We suppose that Mr. Clements would barely maintain 

 that the N occurs as nitric acid in nitromethane or any 

 of its analogous compounds ; but we should be very much 

 surprised if he or any one else could make a correct de- 

 termination of the nitrogen in those compounds by his 

 ammonia method ; and would it surprise him to learn 

 that when N occurs as a component of cyanogen it may 

 be correctly estimated by th. ammonia method? What 

 is the meaning of the remainder of the preceding extract ? 

 Having filled the tube with " some carbonate " and mer- 

 curic oxide, what is the student to do with the Benjamin's 

 mess, the ingredients of which are enumerated in the next 

 sentence, if a heap of words without a single predicate can 

 be called a sentence ? Without doubt the author meant 

 a mixture of cupric and mercuric oxides by " a mixture 

 of the oxide of copper and mercury," but a beginner, we 

 should unhesitatingly say, would mix metallic mercury 



with oxide of copper if he had no other guide than this 

 book. Then what mortar, trough, tubulure, and vessel 

 are referred to ? Where are they to come from, and what 

 are they used for ? A chemist may guess what is meant, 

 but heaven help the beginner who tries to make his first 

 nitrogen determination with the sole aid of this new light. 

 We cannot believe it possible for a man who had ever 

 " done a combustion " to have penned these pages 3-13. 



We have neither space nor patience for further extracts 

 from the author's description of processes and apparatus, 

 but we would ask the reader to refer to pp. 164 and 165, 

 where Messrs. Frankland and Ward's gas apparatus is 

 described, and after he has read it let him try to find out 

 how it was possible for a person who had ever seen the 

 apparatus to write that description ? or even if he had 

 never seen it, how could he ignore the simplest principles 

 of physics and propose to drive the gas from A by simply 

 elevating M ? The drawings and explanation are wo- 

 fuUy incomplete and misleading. 



It is needless to point out all the errors of the author, 

 but there is one class we cannot help referring to, as it 

 gives us a fair test of the extent of the author's knowledge 

 of his subject. To translate constitutional to graphic 

 formulae is considered a very elementary exercise, but in 

 this our author fails miserably; thus he gives (p. 219) : — 



r COHo 

 1 CH 



Succinic Acid < p^^ 



(cOHo 



II 



H— O— C- 



H— 0-C 



I I 



H 



I 

 -C— O— H" 



C— O— H 



where the two lower atoms of C are represented as 

 bivalent. On the same page he gives — 



H 



/COHo 

 " Tartaric Acid \ ^^^ 



icono 



H 



I I 



H— O— C— O— C— O— H " 



i I 



H— O— C— O— C— O— H 



where, as in the preceding, we have no oxatyl group in the 

 graphic formula, although we have two such in each of 

 the constitutional. Again, on p. 225 we have — 



H H 



I i 

 H— O— C— C— C— O— H.' ' 



II I I 

 O H H 



H H H H 



" Lactic Acid 



CMeHHo 

 COHo 



"Mercuric Ethide, HgEtj H— C— C— C— C— Hg— H." 



H H H H 



Where is the group Me in the first and the two groups of 

 Et in the second } But to crown all he has begun this 

 glorious page thus — 



H H 



"Methylic Ether, ^^^ \ O H— C~C-0— H." 



H H 



Is it possible that he does not know that this is the 

 graphic formula of ethylic alcohol, EtHo, a very dif- 

 ferent compound indeed from MejO ? We will not 

 multiply instances, though we might very easily do so ; 



